Riverside Firemen’s Retreat

The Riverside Firemen’s Retreat


A Valuable Reference for Twenty-first Century Firefighters Serving Districts in Any Setting: Metropolitan or Micropolitan, Urban or Suburban, Developed or Rural 

www.fireattackstrategy.com—An examination of legacy firefighting strategies and tactics with emphasis on their correlation to newly emerging principles of fire science and firefighting technique.


March 10, 2023

      • Formula for Estimating Total Water Supply w/ Examples
      • Updated Links to Online Resources on Fire Dynamics, Fire Attack, Home Fire Sprinklers, I.S.O. Ratings, and More
      • Links to Online Resources for Fighting Silo Fires
      • New Tanker/Tender Graphics
      • New Graphics for Selecting a Suitable Fire Attack Based Upon the Phase of the Fire

Home of the Fire Attack Strategy “Coach’s Card”

Fire Attack Strategy "Coaches Card" thumbnail at fireattackstrategy.com
Click the image to view the Fire Attack Strategy “Coach’s Card” (PDF file).  Download and print it legal size, then laminate it to create a two-sided reference similar to a football coach’s play chart.  Commentary on this page describes the concepts found on the card.  There are numerous other downloads including pre-connected hoseline charts and much more.  Check it out!

WELCOME to our hideout—the susquehannawildlife.net Riverside Firemen’s Retreat page—where firefighting wisdom and commentary is shared beneath the shade of the trees around a weathered old picnic table overlooking our scenic thought-provoking watercourse.  Do stick around.  You won’t be sorry.

An Urgent Message from the Editor:

If you’re not a firefighter, you’re still certainly welcome to explore fireattackstrategy.com—because new discoveries regarding the behavior of fires inside buildings are of great import to everyone.  While you’re here, you’ll gain a better understanding of how a fire burns.  You may even discover an appreciation for the challenges presented to firefighters tasked with extinguishing a burning structure; and you may realize that a great deal of science and planning is incorporated into their fire suppression and rescue methods.  Without a doubt, you’ll place enhanced priority on early smoke, fire, and carbon monoxide detection in your home.  Perhaps you’ll even consider the peace of mind that the installation of residential automatic fire sprinklers could provide.  You’ll want to be sure that your family has a plan for rapidly exiting your home in the event of a detector activation or fire.  You may even be inspired to make the increased dangers of home fires a topic of discussion with those close to you.  And please inform any career or volunteer firefighters who may be your relatives, friends, or acquaintances about this site.

You may want to know what this is all about.  Well, here it is.  Firefighters are adjusting the way they extinguish fires, and it all has to do with the hydrocarbons in your home.

The plastics around your house, the foam in your furniture, and the air-tight construction of your dwelling all conspire to create fires that are only limited in intensity and speed by the amount of fresh air they can get.  We call these ventilation-controlled or ventilation-limited fires.

Firefighting methods on the other hand were developed decades ago to fight blazes with intensities and rates of growth determined by the form and position of the combustible fuel—mostly wood.  Think of how a campfire burns with respect to the placement of the logs.  We call these fuel-controlled or fuel-limited fires, and they are decreasing in frequency.

Experiments are showing that fires in rooms furnished with modern (mostly synthetic) items can become totally engulfed (flashover) in fire in as little as three minutes.  A fire in the same room with legacy furnishings from the mid-to-late twentieth century could take as long as thirty minutes to do the same. 

A National Institute of Standards and Technology (N.I.S.T.) Engineering Laboratory test of residential fire sprinklers. Two identical cells were test burned, both equipped with smoke detectors.  Test Room A lacked sprinklers.  Test Room B was fitted with an automatic residential sprinkler system.  Both 12′ x 12′ x 8′ “living rooms” were furnished with a modern sofa, love seat, table, lamp, and carpeting.  Following ignition with a match dropped on a sofa cushion, the fire reached “flashover” in just 3 minutes and 15 seconds in the unsprinklered Test Room A (seen here), totally engulfing the room and all contents.  As the fire roared out of the test enclosure, the temperature reached more than 1,100 degrees Fahrenheit.  (N.I.S.T. Image)

What does all this mean?  Well, residents have less time to discover and escape a fire, so everyone needs to have multiple smoke detectors around their home to provide an early warning—and they need to be operational at all times (hard-wired or 10-year lithium battery units are best).  If there is a fire, quickly get everyone out and close the door(s) behind you—and don’t go back inside.  In as little as two minutes, a modern fire can consume enough oxygen in a closed room to prevent it from flashing and becoming fully engulfed in flame, but it’s also deadly toxic in there.  You could fall unconscious within moments if you try to go back inside—so don’t do it.  Do you understand what I’m saying to you?  The byproducts of combustion including super-heated fuels and poisonous smoke are still in the room, so keeping it closed up provides firefighters wearing bottled breathing air with time to arrive and make ready to apply water for extinguishment and hopefully rescue anyone who couldn’t escape.  The same holds true for apartments and rooms in multi-unit housing too.  Closing the door(s) behind you on the way out can save lives by preventing the spread of smoke and fire into shared hallways, stairwells, and additional units on the fire floor and above. 

You need to get into the practice of keeping the doors closed throughout your home.  Keep the cellar door closed.  Keep the door between the garage and the house closed.  And most of all, keep the doors to bedrooms closed while you’re sleeping.  Closed doors reduce the amount of oxygen available to a growing fire, thus reducing the amount of heat that can be released.  They also contain a fire to prevent it, and much of the smoke it produces, from spreading throughout the house.  Closed doors can improve the chances of survival for occupants in areas of a home that might otherwise be subjected to deadly levels of heat and toxic byproducts from fire.  So, close the doors.  Do it all the time.

It’s probably obvious by now that everyone needs to know how to get out of their home as quickly as possible.  Think about how you’ll get out.  Make a sketch of your exit plan and use one of those silly little magnets to hang it on the refrigerator door.  Do it now so you don’t forget.

Three minutes…can you be alerted to a fire and get everyone out in less than three minutes?  I wasn’t so sure, and I’m as fit as any of you.  I installed automatic fire sprinklers to cover my way out.  That’s it—just to get out.  I should have done it a long time ago, but I absolutely needed to do it now.

Can you get out?  Can everyone get out?


A view inside Test Room B during the National Institute of Standards and Technology Engineering Laboratory’s residential fire sprinkler test.  One minute and 25 seconds after ignition, the sprinkler system activated, containing the fire to the sofa cushion where it originated.  During the experiments, smoke detectors activated approximately 40 seconds after ignition in both Test Rooms A and B.  (N.I.S.T. Image)
An automatic fire sprinkler.
Each automatic fire sprinkler head activates independently of others on the system.  It initiates flow only when its fusible link that holds back the water is exposed to the heat released from a fire.
A modern-day fire can engulf your home before your local fire department ever has a chance to do anything about it.  Without automatic fire sprinklers, your home and possessions could be totally destroyed long before the fire trucks are coming up around the bend.  (Image courtesy of Home Fire Sprinkler Coalition)
You need to look out for yourself and your family.  To provide early warning, you need multiple fire, smoke, and carbon monoxide detectors.  To contain the fire while everyone evacuates, you need automatic fire sprinklers.  Without them, the odds of everyone escaping are reduced.  With them, you might be dialing 911 to tell dispatchers that the fire is already out.  (Image courtesy of Home Fire Sprinkler Coalition)
The choice is yours, fast-acting home fire sprinklers (left), or no fast-acting home fire sprinklers (right).  (Image courtesy of Home Fire Sprinkler Coalition)

After hundreds of hours around that familiar table, here’s what we’ve learned.  It’s the thoughts and words of the sages archived in piles of papers and notes, then transcribed here—straight from the clutter of the editor’s desk.  We’ve incorporated the newest technology of today with the proven techniques of yesteryear.  It’s old and it’s new.  It’s tried and it’s true.  And it’s all just for you…




Fire Attack Strategy—Simplicity becomes a confusing myth…



Fire Attack Tactics—An Introduction



Structural Fire Offensive Fire Attack Tactics—”Fast Water” Structural Transitional Attack and Blitz Attack



Compartment Fire Offensive Fire Attack Tactics—Pulse/3-D Transitional Attack



Compartment Fire Defensive Fire Attack Strategy—Indirect “Fog” Fire Attack



Structural Fire Defensive Fire Attack Tactics— Exterior Fire Attack (Surround & Drown, etc.)



Water Supply—Hydrants



Water Supply—Backup/Redundancy When Using Hydrants



Water Supply—Rural



Water Supply—Estimating Total Water Supply



Water Supply—Planning Response Assignments



Water Supply—Response Assignments in Hydranted Districts



Water Supply—Response Assignments in Rural Districts



The Strategic Pre-Fire Plan—A Quick Reference for Initiating Fire Attack



Hose Loads and Hydraulics—Plan Ahead



Selecting Hoselines for Fire Attack—A size-up really is about size


FIRE ATTACK STRATEGY— An operational framework within which suitable tactics and tasks are employed to mitigate a fire incident and achieve the objective of protecting life and property.

An example of fire attack strategy, tactics, and tasks.
Within its operational framework, a firefighting strategy employs one or more tactics to achieve the objectives of saving lives, extinguishing fire, and protecting property.  Numerous tasks are performed to meet these goals and obtain the most favorable outcome possible.  Obviously, larger incidents may require more extensive operational plans than smaller ones.  This sample diagram of a basic plan for mitigating a structural fire includes an abbreviated representation of the task assignments required to complete the operation.


Fire Attack Strategy

—Simplicity becomes a confusing myth…

Let us first dispel a myth that has infiltrated and confused the fire service since at least the 1980s—that offensive fire attack strategy is defined as fighting a fire that is located inside a building by applying water from a position on the interior of that building, and that defensive fire attack strategy is defined as fighting a fire by applying water from the exterior of a building.

Fire Command by Alan Brunacini.
“Fire Command” (1985) by Alan V. Brunacini, et al.  This landmark book introduced thousands of suburban and rural fire departments to their first incident command system.  It remains a good addition to any firefighter’s library and is available used.  It, like dozens of books since, simplifies fire attack strategy for the student by defining offensive strategy as synonymous with interior firefighting and defensive strategy as synonymous with exterior firefighting.  Unfortunately, this over-simplification continues in present-day publications and has confused the understanding of fire attack strategy and tactics.  (This book does, however, make clear that “stage” and “park” are not synonymous terms.  Complete instruction is provided so that the reader might learn to use staging as an effective tactical reserve and deployment tool.  Check it out!)

It’s important to know that a fire does not have a brain.  Despite comments to the contrary, a fire does not have a mind of its own.  A fire doesn’t know whether the water that doused it was applied from inside a building or from the outside.

A firefighter on the other hand does have a brain.  And a firefighter, hopefully exercising the fortitude to set aside bravado and subdue impulses fueled by adrenaline, can learn the timing and methods necessary to judiciously apply water from the inside and/or outside of a building to extinguish a fire.  Such a firefighter may even learn to evaluate fire conditions to decide whether it is a compartment fire or a structural fire that he or she is facing.  This firefighter may possess the reasoning skills required to determine an effective fire attack strategy, and could perhaps select the appropriate fire attack tactics to quench the mighty-smart fire.  This firefighter would have the wits to know that offensive fire attack strategy uses suitable tactics to extinguish the main body of fire, and usually includes advancing maneuvers to accomplish this goal.  This firefighter would find offensive strategy desirable because it eliminates most of the fireground problems by promptly eliminating the fire.  And this firefighter would know that offensive fire attack strategy can be used on fires inside or outside of buildings and can be the framework of tactics that apply water from the interior and/or exterior of a building.  Smart firefighter.

Chief Edward P. McAniff, in his landmark book Strategic Concepts in Fire Fighting, made clear in 1974 that offensive strategy focuses upon the extinguishment of the main body of fire, “A direct attack is made on the seat of the fire or on the immediate area involved in fire.”  His numerous examples and case studies make it clear that offensive fire attack strategy can utilize a wide variety of tactics to extinguish the main body of fire.  These include hand-held hoselines operating from interior positions, hoselines operating from exterior positions, and master streams knocking down and cooling interior fires prior to the advancement of hand-held hoselines.

There is a case study where Chief McAniff described, “…darkening the fire with exterior streams and then endeavoring to change the strategy to an interior attack…”.   For a fire engulfing the third floor of a four-story old-type loft building, McAniff advocates initiating a defensive strategy and using exterior master streams to control extension and darken the fire if possible—as would normally be the course of action in such a scenario.  However, in this case, because of a light fuel load inside the building, he advocates using the master streams to take a shot at knocking down the fire possessing the third floor.  If these streams make headway, hand-held hoselines are to be directed through the windows at the fire and, if the opportunity presents itself, advanced to complete its extinguishment.  Chief McAniff is describing something that may resemble, using our present-day terminology, a large-scale prolonged hybrid of a Blitz Attack and a “Fast Water” Structural Transitional Attack, waged against the main body of fire—all to carry out an offensive fire attack strategy.  For McAniff, knowing that the construction of this type of building may tolerate a sustained “bombardment” by exterior streams, this was a long shot to be tried as part of the defensive strategy.  If it was successful and crews could make entry, the fire attack strategy would be revised to an offensive one using the interior positions to apply water to the seat of the fire.  If the heavy streams were not effective, the defensive strategy would be retained for the duration of the incident.  In this particular case study, unlike anywhere else in the book, McAniff seems to casually refer to interior attack as a strategy, perhaps to be descriptive of the momentous achievement that advancing on such an enormous fire would have been.  Elsewhere in his work, he doesn’t routinely indicate that a position from which water is applied is what defines a strategy—just the opposite.  Today, we could look at this case study as an extraordinary example of an offensive strategy initiated by the use of a tactic (applying water with a master stream to diminish the fire) that is common to both offensive strategy and defensive strategy.


One of McAniff’s fundamental examples is the use of a master stream to diminish the fire in a very large pile of burning building materials stored outdoors between an occupied multi-story combustible tenement and an unoccupied church undergoing renovations.  (Editor’s Note: Please understand that this is a blaze engulfing a massive stack of lumber, enough wood to build a house or two.  For this example of a defensive fire attack strategy and the next, the pile of burning lumber could just as well be a large wood frame structure fully involved in fire.)  The fire has already spread to the church and the hallways of the tenement, so the chief on the scene, having adequate water supply and manpower to do so, chooses to use a master stream to reduce the heat release rate from the burning materials and cover the windows of the tenement to provide crews with a chance to stretch hand-held hoselines inside to stop the fire from extending further into the occupied building.  The chief uses his resources at hand to overcome the critical strategic (limiting) factor for this fire—fire extending into an occupied exposure building is compromising egress routes for endangered residents in need of evacuation/rescue.  The church is written off as a total loss.  This is a defensive fire attack strategy.  Its purpose is to control extension to provide life safety for occupants of the adjacent multiple dwelling.  And please note that hoselines are positioned and operated both on the exterior and the interior of the buildings.


Let’s suppose for the next several scenarios that the fire department has arrived earlier, before the burning materials have spread fire into the exposures—the church and tenement.  And let’s say the chief has at his/her disposal just one engine company, and they alone cannot meet the fire flow requirements needed to extinguish or adequately cool the large pile of burning lumber.  Now there is a new limiting factor to overcome in addition to the life hazard in the tenement— there is an insufficient water supply.  The chief may again need to select a defensive fire attack strategy, and once again all efforts would be directed toward protecting the occupied tenement long enough to get everyone out.   But now it must be accomplished by conservatively using a deficient fire flow to cool the building’s exterior, and without the benefit of cooling the large pile of burning construction materials.  To delay the extension of the fire into the tenement, the effort will need to concentrate on cooling the wall, and particularly the windows, on the side facing the burning lumber pile.  It may become necessary to stretch hand-held hoselines to the interior to protect the hallways as egress routes, so the chief must manage fire streams carefully.  He/she must anticipate the loss of both buildings and get all the occupants out of the tenement by using his/her limited fire flow to protect that effort.  This is again a defensive fire attack strategy.  However, the additional limiting factor creates the need for these new tactics in order to achieve the best possible outcome.

A defensive fire attack strategy.
A first-in engine company with an available flow of just 500 G.P.M. may be able to buy enough time to get everyone out of the multi-unit dwelling safely.  To protect the tenement from convective and radiant heat, a portable multiversal “step gun” equipped with an “automatic” fixed-pressure combination nozzle can be positioned by just one firefighter to be used as an unmanned monitor using as little as 300 G.P.M. (or less) to cool the exposed wall and windows with a wide cone of water fog spray.  The crew is then free to stretch a hand-held hoseline(s) to protect the stairway and corridors while the residents are evacuated.  If the available flow is significantly less than 500 G.P.M., say 250 G.P.M., the use of only the hand-held hoseline(s) may be a chief’s best option.


Perhaps the chief’s defensive strategy is just a temporary measure to contain the fire until circumstances are more favorable for its extinguishment.  Maybe he/she anticipates the eventual arrival of companies that can secure additional water supplies and improve the flow at the scene, but it’s going to take some time to get everything set up.  In that case, the chief may again order the first-arriving companies to use their limited flow capabilities to protect the tenement while it is evacuated.  And as before, it may be necessary, early on, to deploy hoselines to the interior to protect exit routes being used by residents.  But then, when later-arriving companies have established a sufficient flow rate at the scene, the chief could order crews to close in on the burning building materials and begin a Direct Attack using master streams and hand-held hoselines to extinguish the fire.  By adding this offensive component (the advance and attack upon the main body of fire) to the operation, the chief has presided over a holding action—a defensive-offensive fire attack strategy.


Arriving to find the flames from the burning pile of lumber posing an immediate threat to the exposure buildings and, in this scenario, having adequate fire flow and resources to not only cool, but to extinguish the main body of fire, the chief could select an offensive fire attack strategy.  To achieve an expeditious knock down, companies lead off with master streams to precede a close-up Direct Attack on the burning fuel using hand-held hoselines.  Eliminating the fire is, of course, the most effective way to contain it.  Quenching the flames mitigates the threat of extension and assures the safety of building occupants.  An offensive fire attack strategy quickly gets the main body of fire extinguished—problems solved!


McAniff also provides examples of the offensive-defensive strategy, one commonly used to fight fires in row houses and other multiple dwellings.  This is an oft used and familiar “bread-and-butter” evolution for many urban fire departments.  Control of the fire being probable, first-arriving companies attack the main body of fire in the house or apartment of origin.  Later-arriving companies, often from a second alarm, are assigned to check extension and extinguish any fire in the exposure buildings or units—those surrounding and above the point of origin.  This is an example of an offensive-defensive fire attack strategy.

Offensive component of an offensive-defensive fire attack strategy.
Here’s an example of an offensive-defensive fire attack strategy for a fire in a row house.  Control being probable, the chief orders the first-arriving companies to quickly use an exterior stream to cool the heated space where fire is showing from the second floor of the involved dwelling.  They then advance lines to the interior and attack the main body of fire to extinguish it (from front and rear as necessary).  Because the chief can apply an adequate water flow onto the seat of the fire, this offensive “Fast Water” Structural Transitional Fire Attack is the most effective way to overcome the strategic (limiting) factor for this incident: the immediate threat of rapid fire extension into attached dwellings.  This is the offensive component of the offensive-defensive fire attack strategy.
Defensive component of an offensive-defensive fire attack strategy.
While the first-arriving companies complete extinguishment in the dwelling where the fire originated, the later-arriving “All Hands” or second alarm companies stretch lines into the exposure buildings to extinguish fire, stop fire extension, and initiate salvage and overhaul.  This is the defensive component of the offensive-defensive fire attack strategy.

Of course, the offensive-defensive fire attack strategy could be used to fight the fire in the tenement and church scenario as well.  Provided the chief can develop and supply the substantial large-caliber fire streams needed to fully extinguish the main body of fire (the burning construction materials), he/she could order this offensive component of the strategy be undertaken by the first-arriving companies.  The later-arriving companies would then be assigned to the defensive component, the stretching of lines into the tenement and the church to check fire extension.  The prospect for fast extinguishment of the main body of fire and timely control of fire extension could make selection of the offensive-defensive strategy a favorable option.

Think of it this way.  If you arrive and there’s a car on fire alongside a building, and you extinguish the main body of fire, the automobile, that’s an offensive strategy.  You can apply water from outside the car and it remains an offensive strategy.  If the auto is burning inside a garage and you choose to extinguish it, whether from outside the building or from a doorway in the attached house, it’s an offensive strategy because you attempted to extinguish the main body of fire, the car.  If you decide in either case not to extinguish the automobile fire and attempt instead to cool the walls of the building and stretch hand-held hoselines to the interior to stop extension while the car burns, it would be a defensive strategy.  If you assign the first-in crews to stretch lines to cool the walls and stop extension until the later-arriving companies deploy foam equipment to extinguish the burning vehicle, this would be a holding action—a defensive-offensive strategy.  And finally, if you first assign crews to extinguish the main body of fire, the automobile, then task the later arriving companies with stretching hand-held hoselines into the building to check extension, it would be an offensive-defensive strategy.

You may be familiar with the term “marginal strategy”.  A “marginal strategy” is essentially a byproduct of the offensive-equals-interior and defensive-equals-exterior mentality.  It is meant to address a well-developed fire by using an offensive interior attack, but it anticipates failure of that effort.  Its basic premise is to send firefighters into the building to operate hand-held hoselines while simultaneously making preparations to attack the fire from the exterior if these crews find it necessary to retreat.  Upon examining the charts and commentary on this page, the reader will soon conclude that the use of this contrivance should be disregarded.  Committing firefighters to an advance into a deep-seated working or marginal working fire requires development of fire streams and tactics capable of sufficiently cooling and “resetting” the fire from the exterior before entry is attempted.  Any advance toward the main body of fire is a wholly offensive strategy, and it will only succeed if firefighters are able to flow water at a rate and efficiency that is sufficient to suppress the heat release rate of the fire.  Using a “marginal strategy” and allowing firefighters to advance toward the main body of fire with hose streams of insufficient caliber under the hope that they might be “aggressive” enough to extinguish it is risky business.  A hose stream with an effective cooling capacity of 10 to 15 megawatts is no match for a deep-seated working fire with a heat release rate of 20 megawatts or more and growing—it’s that simple.  A key component of the “marginal strategy” is the development of water supplies and the placement of backup lines and master streams as a contingency in case the advancing firefighters are forced to back out.  This is certainly sound policy for any fire attack.  But wouldn’t you think that at least one larger caliber stream might be better used if it were to be promptly flowed into the burning building to reduce the heat release rate before firefighters advance inside toward the seat of the fire?  It’s something an ambitious firefighter really ought to think about.

McAniff’s strategies are the foundation for the “Fire Attack Strategy Coach’s Card” found below.  Among the tactics shown are several transitional fire attacks.  Hopefully, it will become clear to the reader that a transitional fire attack tactic merely includes a movement from an exterior water application position to an interior application position as part of the cooling process and advancement toward the seat of the fire.  More precisely, the defining component of a transitional fire attack is the advancement of hoselines from positions taken for indirect cooling to positions taken to apply water directly onto the burning fuel to extinguish the fire.  It does not include, nor does it indicate, a change in fire attack strategy.  These are wholly tactics for an offensive strategy targeted at extinguishment of the main body of fire.  As we’ll see, most offensive fire attacks use some form of indirect cooling preceding direct application of water to burning fuel, thus all these offensive attacks are “transitional” in practice.

One final point of clarification.  Many of the most current books on strategy and tactics continue to associate a redeployment of hoselines with a change in strategy.  When interior firefighting crews fail to make headway against a stubborn fire or become overwhelmed by an extreme fire behavior event such as a flashover, they are often ordered to withdraw from the structure, then exterior streams are directed into the fire building by the same or backup crews.  In many publications, this event is described in the text or in a caption on a set of photographs as a transition from an offensive attack or strategy to a defensive attack or strategy.  In at least one very recent (2017) book, the author cautions the student not to confuse the “new” transitional fire attack tactics that are being introduced therein with the transition of strategies being shown in an example.  The given example illustrates a redeployment from interior firefighting positions for water application to exterior positions for water application during an uncontrolled fire.  The water continues to be directed at the main body of fire—the classic offensive fire attack strategy, though the author describes the evolution as a “transition” to a defensive strategy.  The author could easily eliminate his/her own confusion, and that of the reader, by more accurately labeling the retreat from the building as a transition in firefighting positions, not a transition in strategy.  The objective (the main body of fire) and possibly the strategy (offensive) have remained unchanged in the author’s example.  If there is any intention to advance hoselines back into the fire building after a period of cooling by exterior streams, then a chief is still operating in an offensive mode using an offensive strategy, which, if conditions have been carefully evaluated, can lead to a successful outcome in many cases.

Now, if, upon withdrawal from the building, the objective changed to the protection of exposures and the majority of hose streams were directed toward containing the flames and controlling extension without crews again maneuvering against the main body of fire, this would constitute a revision of strategy to defensive.  When progress is not being made against a fire, particularly in a building with light-weight construction, the chief would be prudent in most instances to order a switch to a defensive strategy.  And upon this change to a defensive strategy, an incident commander better think long and hard before sending anyone back inside the fire building for any reason, at any subsequent time.  Allowing crews to reenter the structure can lead firefighters to believe that the incident commander is oscillating between strategies and may leave them wondering what the fire strategy might be at a particular moment.  This is a dangerous situation that needs to be mitigated before it proves deadly.  It is critical that companies on the fireground are aware of the strategy being used to fight the fire.

Remember, the key factor setting the defensive strategy apart from the offensive is its lack of advancing maneuvers against the main body of fire.  Offensive operations can include the use of exterior streams to contain, cool, and sometimes extinguish the main body of fire, but tactics that advance hoselines to attack and extinguish that main body of fire are the defining elements of the strategy.  During defensive operations, hose streams can be used to contain, cool, and even extinguish the main body of fire, but lines are not moved forward into involved areas to achieve advantageous positions for extinguishment of the fire at any time.

Excellent, I think you’ve got it!

Strategic Concepts in Fire Fighting by Edward P. McAniff
“Strategic Concepts in Fire Fighting” (1974) by Edward P. McAniff (Retired Chief of Department, F.D.N.Y.), is the landmark fire strategy book.  It is indispensable to firefighters desiring to understand fire attack strategy.  McAniff encourages the incident commander to identify the fire’s one or two most critical limiting (strategic) factors, then select the strategy and tactics that best overcome these factors or gain the most favorable outcome possible while operating within their limitations.  If you remember that Chief McAniff is describing firefighters extinguishing primarily fuel-controlled fires without the advantage of using bottled breathing air, and you can understand how that correlates with his aggressive use of ventilation and concern for “pushing fire” with hose streams, you won’t be distracted by several outdated methods and will be able take a vast amount of knowledge away from this read.  This book is available used and really ought to be re-published with inclusion of some editorial revision authored by some of the fire behavior researchers…hint-hint.

And now, the card…

BUILDING FIRE STAGES AND FIRE ATTACK STRATEGY AND TACTICS is a two-sided matrix of firefighting strategy and tactics “coach’s card”.  This firefighter training aid, study guide, and conversation starter presents time-tested firefighting concepts with systematic incorporation of newer tactics developed as a result of recent research into modern fire behavior and dynamics.  Stages and phases of the fire are used to guide the reader to the strategic and tactical options for extinguishment.  Control of the ventilation flow path and three transitional fire attack choices are included as techniques which may enable crews to fight the fire in its “4th dimension”—slowing the fire’s growth, stopping its forward progress, and/or reducing its heat release rate to that of an earlier time.  Printed legal size or larger and laminated, this colorful reference chart is similar in style to a North American football coach’s play card.  A must have for fire officers learning to command a fireground.


View by clicking the image below…

Building Fire Stages and Fire Attack Strategy and Tactics "Coach's Card" thumbnail.
The Building Fire Stages and Fire Attack Strategy and Tactics “Coach’s Card”.  Click the image to view the PDF file.  Download and print it legal size, then laminate it to create a two-sided reference similar to a football coach’s play chart.

Perhaps by now you’re quite curious about Fire Attack Strategy and Tactics and would like to do a bit more research on your own.  This is an admirable trait and would be time well spent for sure.

Wizard of Oz Interlude…

Recall, if you will, the scarecrow.  You remember the poor scarecrow.  The scarecrow’s great limitation in life was that he did not have a brain.  So, the troubled scarecrow was guided to the wizard.  And the wizard did bestow upon the scarecrow a piece of paper, a diploma, upon which it was written that the reader may be assured that the scarecrow is scholarly, sayeth the wizard.

By now, everyone knows that the wizard was a hoaxster, a fraud, you know, a con man.  Scarecrows don’t have brains, even if a piece of paper declares that they do.  But let us just imagine for the moment, for the sake of the story, that a fictional scarecrow was walking around and talking.  Such a scarecrow would have a brain.  The wizard merely awarded the scarecrow with a piece of paper to boost his self-esteem and confidence; his intellect remained the same.  Perhaps, with fortitude, the scarecrow could use the confidence bestowed upon him by the wizard to become more studious and committed to a lifetime of learning.  This would be the smart thing for the scarecrow to do.  Because the scarecrow needs to guard against lethargy and pride, for he may be overcome by hubris and could develop a dismissive attitude toward those he meets, becoming henceforth known as a fool.

Now, the scarecrow can’t be a firefighter (you’ll recall that he burns and therefore has a fear of fire).  However, if the scarecrow was a firefighter, maybe he would be self-motivated and would seek formal education in the fire sciences or would read and study all that he could about fire behavior.  Perhaps he would exercise his mind by doing mathematics to analyze the water supplies and flow requirements in his fire district.  His dedication to practicing and drilling could sharpen his firefighting skills.  He may have a passion for keeping up with the most recent developments in fire dynamics research.  Ultimately, his education would give him the ability to comprehend and understand his experiences.  Then, the scarecrow would possess wisdom, and the piece of paper he received from the wizard might have significance after all.

…End of Interlude.


Fire Attack Tactics

—An Introduction

If you like to read, enjoy perusing charts, and like being enlightened by the revelations of the fire sciences, including the math if it’s not too intense, then here is a discussion of a few more books, reference materials, and other resources that you may find useful.  The content can provide you with the ability to better comprehend fire attack strategy and tactics.  This information could help you broaden your department’s strategic and tactical capabilities, and possibly realize some deficiencies in need of correction.  During a fire, a lack of prior preparation by the fire department can add unnecessary limiting factors which must be considered when selecting a fire attack strategy.  Inadequate or improper planning may lead a commander to have no alternative but to select a defensive strategy, otherwise fire crews may be placed in peril.  These shortfalls could also predispose to failure some or all of your fire attack strategies and/or tactics, leaving both firefighters and the public they serve at risk.

Let’s begin with a couple of important definitions followed by descriptions of some fundamental fire attack tactics that can be employed within the framework of the fire attack strategies we’ve just covered.  Then we’ll take a look at water supply and methods available to reduce its prevalence as a limiting factor on the fireground.

Compartment Fire (Enclosure Fire)- A building fire within an enclosed space or spaces (often a room, apartment, basement, attic, office, mobile home, etc.).  A compartment fire typically involves contents and coverings within the building and has not progressed to involve major structural components.  The blaze begins as a fuel-controlled fire in the incipient phase (fire in a waste can, piece of furniture, pan on a stove, etc.).  As the heat release rate increases, the fire enters a growth phase and becomes ventilation controlled as additional fuel is vaporized from pyrolyzed combustibles and oxygen is consumed.  If there is not an adequate source of incoming air, the lack of sufficient oxygen causes the fire to enter an initial decay phase and the heat release rate decreases.  Lacking a fresh air supply and smoldering for an extended period of time, the fire may eventually self-extinguish.  More often however, introduction of air by a ventilation event (someone opening a door or a window breaking) oxidizes accumulated fuel vapors.  They burst into flame, raising the heat release rate and allowing the growth phase to resume, often with great ferocity—the blaze quickly becoming a structural fire.

The smoke and gases produced by initial decay phase conditions are eventually deadly to occupants of the compartment.  When exposed to an air supply and source of ignition, hot gases accumulated during the initial decay phase are sometimes the fuel for extreme fire behavior events that are deadly to firefighters too. These include smoke explosions, backdraft explosions, and rapid fire growth—the latter culminating in flashover.

To prevent potentially catastrophic events, the Pulse/3-D Transitional Attack and Indirect “Fog” Attack are used to fight fires in enclosures—the former as an offensive measure during the fire’s incipient phase and growth phase, the latter as a defensive measure during its initial decay phase.  The Pulse/3-D Transitional Attack uses pulses of water fog to cool the gaseous layer during an interior advance to the main body of fire, which is extinguished using direct application of water onto the burning fuel.  The defensive Indirect “Fog” Fire Attack on the other hand, relies predominantly upon thirty seconds of water fog application from the exterior of the enclosure to extinguish the fire.  Entry to apply water directly onto burning fuel occurs only as an overhaul task.  As a fail-safe, regardless of the attack used, adequate hoselines are deployed to provide backup to those fighting a compartment fire.  A human error or a pane of glass breaking due to the heat could quickly ventilate the fire and convert the incident into a structural fire.

Compartment fire research has its roots predominantly in Sweden.  The Pulse/3-D Transitional Attack was developed there in the early 1980s to improve firefighter safety while extinguishing them.  For a detailed account of these fires describing their dangers, development, and physics, including mathematical analysis, all in English, see:

Bengtssan, Lars-Göran.  2001.  Enclosure Fires.  Swedish Rescue Services Agency.

Structural Fire- A fire involving the structural components of a building.  A compartment fire with an adequate air supply can continue in the growth phase (without entering an initial decay phase) becoming a structural fire as the exponential pyrolysis of combustible surfaces provides an abundance of vaporized (and oxidized) fuel, thus raising the heat release rate rapidly without interruption.  Under these conditions, flashover can ensue within three minutes of the start of the fire—victims in the fire area will not survive.

A compartment fire that is ventilated during its initial decay phase can enter a catastrophically intense growth phase as well, becoming a structural fire and reaching flashover before firefighters have time to react.

Structural fires, though often provided with an abundance of fresh air, continue to burn as ventilation-controlled fires until well into the vented (final) decay phase.  This burning regime is evident at nearly every large fire as flames can be seen raging within clouds of hot fuel-rich smoke issuing from window openings but are not visible within the structure—the oxygen level there is insufficient to support combustion.  Following flashover, a structural fire soon becomes fully developed.  Thereafter, the fire enters the vented (final) decay phase, and the heat release rate begins to decline as the fuel provided by the burning structure is consumed.   The fire can still pose a significant risk to exposure buildings as the accumulated heat causes pyrolysis of their combustible surfaces and the main body of fire is still hot enough to ignite the vaporized fuel.  Eventually, the weakened structure is likely to collapse, which can result in a sudden spike in heat release rate—again putting exposures at risk.  By the time the remaining fuel resembles a large campfire instead of a building, the fire is returning to a fuel-controlled burning regime, just as it began.

The “Fast Water” Structural Transitional Fire Attack and Blitz Attack are effective offensive tactics for extinguishing structural fires during that short period of rapid fire growth preceding flashover and the fully developed phase.  Both initiate cooling of the fire with an expeditious application of water from the building’s exterior (as needed) to turn back the rapid growth and buy time for an interior advance to extinguish the remaining flames and conduct search and rescue.  The Exterior Fire Attack (Surround and Drown, etc.) is a defensive measure employed to contain and extinguish structural fires that have become fully developed and/or exceed the capabilities of offensive tactics.

The stage and phase of the fire are often among the most important factors for a fire officer to consider when selecting fire attack strategy and tactics.  Because it is usually outwardly evident, the stage of the fire (smoke showing, working fire, marginal working fire, fully-involved, etc.) may strongly influence the selection, but priority should also be given to the phase of the fire, as well as its classification—compartment fire or structural fire.

Determine the phase of the fire to select the fire attack tactic.
The phase of the fire should strongly influence the selection of the Fire Attack Tactic to be employed.


Structural Fire Offensive Fire Attack Tactics

—”Fast Water” Structural Transitional Attack and Blitz Attack

"Fast Water" Structural Transitional Attack

Upon arrival at a fire scene, does your fire department differentiate between a compartment fire and a structural fire?  Do you employ a different set of tactics for each?  Is your fire department training, drilling, and equipping its companies to safely and effectively knock down and extinguish structural fires?  Do you have a “fast water” pre-connected hand-held hoseline ready to be quickly deployed to slow down or turn back a runaway structural fire?  Did you practice tank-dump “Blitz Attack” during your drills so that you may have a shot at knocking down and “resetting” a deep-seated or marginal working fire?  Do you conduct coordinated structural fire drills that include: “resetting” the fire using tank water, supply hose hook-up, breathing air and protective gear donning, the advancement of interior hoselines, a Direct Attack on the seat of the fire, and secondary water supply and back-up hoseline deployment?

Humans at some point in time learned that applying a liquid to a burning fire would extinguish the flames.  You may be imagining how that first took place, and you’d probably be correct.  Eventually, a vessel as simple as a tortoise shell may have been the first fire extinguisher.

As humans began constructing combustible structures for shelter, a mishap with a cooking or heating fire posed a threat of instant catastrophe.  The ability to douse a fire with water could spare the residents of these early dwellings the hardship of exposure to the elements until a new shelter could be built.  A home could be saved by the expeditious application of water to the seat of the fire.  The knowledge of fire extinguishment was a basic survival necessity.

As time went by, societies developed organized efforts to extinguish fires and prevent their spread.  In North America, leather buckets replaced pottery for dumping water onto burning material.  During a fire, residents would form bucket brigades to relay water from a source to the fire.  During the late 1700s and early 1800s, hand-operated hydraulions were manufactured to pump water through a hose and nozzle for soaking the fire.  These were followed by pressurized fire hydrants, horse-drawn steam-powered pumps, and motorized fire pumpers.  The method remained the same—apply water onto the burning material to extinguish the flames.  It was a task that came to be known as a “Direct Attack”.

Leather Fire Bucket
In many municipalities, residents were required to own a leather fire bucket.  This example is marked with the owner’s name to assure its return after use in a bucket brigade relay.  (Smithsonian image, www.si.edu)
A fire hydraulion or hand pumper.
Hydraulions like this circa 1788 model were hand drawn to the fire scene.  The pump was operated by hand as well.  (Exhibit: State Museum of Pennsylvania, Harrisburg)

The hose and nozzle provided the means to fight fires in the ever larger and more complicated multi-room and multi-floor structures of modern times.  Firefighters advancing deeper into burning buildings were challenged by hot smoky conditions, which they often relieved by ventilating the building.  Fortunately for them, the very simple combustibles, mostly wood, allowed them time (as long as 30 minutes) to locate and extinguish a fire before a flashover would occur.  Nevertheless, hundreds of firefighters died during these interior fire attacks.

Since World War II, man-made materials, particularly plastics, comprise an ever-increasing percentage of the mass of the fuel in burning buildings.  The more this percentage grows, the greater the heat release rate of the fires.  If the fire continues to have a supply of oxygen, this increase in man-made fuel mass also corresponds to a decrease in time to flashover.  An incipient phase fire in a piece of upholstered furniture can rapidly progress to growth phase and can reach flashover and become a structural fire in just three minutes.  In closed spaces, these modern fires can reduce the oxygen percentage to 15% or less and cease to support combustion in less than three minutes.  This smoldering fire can quickly intensify if oxygen reenters the compartment.  The result can be deadly— an extreme fire behavior event.

Early on, firefighters coped with the increasing speed and heat release rate of fires by adopting new techniques.  Many departments had turned to water fog as a method of attack that included indirect cooling of the three-dimensional space surrounding the fire.  Those departments that continued to use smooth-bore nozzles for “Direct Attack” extinguishment increased their use of straight streams for indirect cooling of heated surfaces as they advanced toward the seat of the fire.  Many began increasing the flow rates of their hand-held hoselines to absorb more heat.

As fire behavior incrementally increased in volatility during the most recent decades, the change was, surprisingly, not obvious.  It was obscured to some extent by the use of new technologies—particularly Self-Contained Breathing Apparatus (S.C.B.A.s) and thermal envelope turn-out gear.  This personal protective equipment enabled firefighters to enter atmospheres that would have been immediately fatal to their predecessors.  To some extent, the new equipment allowed firefighters to remain on the “front foot” in the suppression effort during the years of steady, but discrete, changes in fire behavior.  The prevalent use of these high-tech turnouts and S.C.B.A.s resulted in sparse recognition of the increasing dangers from extreme fire behavior.  While the new personal protective ensemble may have been “bullet-proof” against the heat from legacy fires, it was proving vulnerable to the heat generated by the extreme fire behavior events occurring during modern fires—firefighters continued to be killed.  Today, we’re realizing that a firefighter wearing full turn-out gear and an S.C.B.A. for protection lacks invincibility and may be as vulnerable as ever—extreme fire behavior has kept up with technology.  (Makes one wonder if those dirty old firemen who insisted upon having a bare hand for feeling the temperature while they put out fires were just being contentious or were on to something.)

Old time firefighting.
In many fire departments, convincing firefighters to wear their personal protective equipment was a gradual process.  (Image by C. Bailey)

Today’s firefighters are well-equipped to advance hoselines to the seat of a fire for extinguishment, but they need to win a potentially deadly game of “beat-the-clock” to do it.  Because the heat release rates are so high when modern combustibles burn, they use up oxygen quickly.  Within minutes, most building fires beyond the incipient phase are in a ventilation-controlled (limited) state.  They’re smoky, fuel-rich, and hot.  Ventilating to improve tenability for victims and firefighters allows more oxygen to enter the building—the heat release rate will increase, and the fire could reach flashover and a fully-developed phase in just minutes.  The temperatures generated during such a rapid fire growth event will cause failure of turn-out gear and S.C.B.A. face pieces.  Ventilation can no longer exhaust heat faster than the heat release rate increases in response to the oxygen enrichment caused by the entry of fresh air.  It’s a strategic (limiting) factor of great import to firefighters trying to suppress today’s structural and compartment fires.  Somehow, you need to quickly cool the heated space inside the building so that you can perform a Direct Attack—stretching a line to the burning fuel, soaking it with water, and quenching the flames.

“Tactical Ventilation”—Controlling the Ventilation Flow Path

Fire dynamics and behavior: Closed doors provide refuge from fire.
Bedroom doors closed at night isolate fires and offer occupants of a building some protection from the heat, smoke, and the toxic byproducts of combustion.  Keeping bedroom doors shut at night can provide sleeping residents with additional time to be alerted to the presence of a fire and escape.
Fire dynamics and behavior/flow path: Smoke and fire spread when bedroom doors are left open.
Bedroom doors left open while residents are sleeping provide no barrier to the heat, smoke, and toxins from a fire.  Within minutes, conditions can be fatal.  The last tenable space is usually within inches of the floor, where temperatures are lowest and where there may still be an adequate concentration of oxygen to support survival.
Fire dynamics and behavior/flow path: Vent Enter Search (VES) gone wrong.
Vent-Enter-Search (V.E.S.) gone wrong.  With interior doors open as firefighters effect a primary search of second floor bedrooms from the porch roof, a window being used for entry can become an exhaust point for the fire, creating a draft that pulls combustion-supporting fresh air (green arrows) into the burning area from another opening, new or preexisting (in this example, firefighters opening the front door).  The resulting increase in the fire’s heat release rate soon places the crew and victim(s) within a potentially deadly ventilation flow path (orange arrows).  A rapid fire growth event, a flashover, is a probability.
Fire dynamics and behavior/flow path: Vent Enter Isolate Search (VEIS), tactical ventilation.
Vent-Enter-Isolate-Search (V.E.I.S.)  To isolate bedrooms and other areas from burning sections of the house and to avoid establishment of a dangerous ventilation flow path, employ the Vent-Enter-Isolate-Search (V.E.I.S.) concept instead.  Search teams entering rooms on or above the fire floor from the exterior must remember to close the interior door(s) immediately upon getting inside.  While it is an improvement over V.E.S., the V.E.I.S. technique is even safer if entry to areas above the fire is preceded by water application to improve conditions inside the building for victims and to reduce the risks to rescue personnel during the primary and secondary searches.  Here, the nozzle operator begins cooling the fire’s gaseous layer with short pulses of water fog to prevent rollover during door entry and maneuvers toward the seat of the fire.  Had this fire intensified to involve the building’s structural members and become self-ventilated, application of a straight stream from an exterior position may have been necessary to cool the affected area before advancing a hoseline to the interior for a Direct Attack on the main body of fire.  Remember this: get water onto a ventilated fire fast!

Paradoxically, the “ventilation” management method that is most effective for improving interior conditions compels firefighters to close up the building instead of opening it up.  Closing doors and closing or covering window openings quickly isolates the fire and deprives it of oxygen, reducing its heat release rate significantly.  This action can put the brakes on rapidly accelerating fire growth and provide the time needed to get hoselines into position for an offensive fire attack.  Not only do “tactical ventilation” methods control the flow path of air within a burning building to prevent new supplies of oxygen from intensifying a fire, but they also stop fire from extending through occupied sections of a structure toward unintended exhaust openings—reducing the threat to victims and would-be rescuers who might otherwise become trapped by torch-like conditions in the fire’s untenable “chimney”.

“Tactical Ventilation” is a momentous operational change for ladder companies who have traditionally made openings early and often.  It requires a more proactive evaluation of the burning structure to determine the fire’s ventilation flow path and to assess the impacts that openings will have on the intensity of the fire and its extension into new areas.  “Tactical Ventilation” measures can be used to great advantage to control the fire’s ventilation flow path and provide conditions favorable to rescue and extinguishment.  To be safe and beneficial, ventilation must occur at the right place at the right time, coordinated with other events on the fireground.  In most cases, this means closing up and isolating the fire during extinguishment efforts, then opening up to ventilate as the operation progresses into salvage and overhaul.  Firefighters should take note that coordinated ventilation, in the words of an increasing number of experts in the field, is ventilation that occurs only after water is flowed onto the main body of fire.  Due to the rapid fire growth and quick flashover produced by modern fuel loads, this is advice worth serious consideration.  It’s a new operational priority—identify and control the ventilation flow path.

A wind-driven fire in a high-rise building extends through an open door into a common corridor.
A wind-driven fire in a high-rise building.  In this cutaway illustration, an apartment fire in a high-rise building has self-ventilated allowing the wind to pressurize the burning space and force smoke, superheated gases, and flame through the open door into the common corridor shared by all units on the depicted floor.  The hallway is untenable for both occupants seeking to evacuate and firefighters attempting to advance hand-held hoselines to extinguish the fire and protect a primary search.
A wind-driven fire in a high-rise building extends from a shared hallway into an apartment with an open door.
Additional apartments can quickly become charged with heat, smoke, and toxic gases when doors entering common corridors are propped open or left ajar by fleeing occupants during a wind-driven fire.  The danger is intensified when open doors allow extension into stairwells and other egress routes adjoining the shared hallways.
Ventilation intensifies a wind-driven fire in a high-rise building.
Ventilation can increase the volume and intensity of a wind-driven fire, allowing flames to incinerate everything and everyone in its flow path.  Always be prepared: a window could fail or be broken at any time.  The result during a wind-driven fire is an almost instantaneous flashover or other rapid fire growth event.  During rescue operations, assure that doors protecting unburned areas from the wind-driven fire are closed, especially when using windows and other exterior openings as egress points.  Always assess a high-rise building’s favorable and unfavorable “shelter-in-place” attributes during pre-fire planning visits, especially those that permit occupants to remain in their dwelling unit or workspace instead of trying to evacuate through common corridors that may be exposed to fire and smoke.  Above all, make certain that automatic door closing devices are installed and are working properly.

In addition to prompt primary search and rescue, an emerging role for ladder companies could be “close and cover” in order to reduce the heat release rate until water can cool and extinguish a fire.  Some departments are experimenting with fire-resistant tarpaulins and metal plates on poles for covering window openings.

A “Wind Control Device” (W.C.D.) is secured in place by four F.D.N.Y. firefighters, two each on the floor above and floor below a windward (upwind side) opening to a fire room.  These modified tarpaulins were used to control the ventilation flow path during high-rise fire experiments conducted on Governor’s Island in New York.  During each test using a W.C.D., temperatures in the corridor and stairway downwind of the fire apartment decreased by 50% within 120 seconds of deployment.  For more information see: “Fire Fighting Tactics Under Wind Driven Fire Conditions: 7 Story Building Experiment” (2009) by Stephen Kerber and Daniel Madrzykowski, N.I.S.T. Technical Note 1629.  (N.I.S.T. Image)
In commemoration of the 50th anniversary of the Apollo moon landings, let’s consider borrowing some rocket science for use in the fire service.  Here we see the primary strut, the foot pad, and the partially buried contact probe on one of the sets of landing gear on the Apollo 11 lunar excursion module (LEM).  The foot pad is connected to the strut using a ball and socket swivel, so that it might make good level contact with the moon’s surface.  With a little ingenuity, a mechanically inclined group of firefighters could use a similar design to fabricate a set of plates on poles for covering window openings to control the ventilation flow path during structural fires.  (NASA Image by Edwin “Buzz” Aldrin)
Firefighters deploy window covers for controlling ventilation flow path.
An assortment of plates, large enough to cover the windows you encounter, could be bolted to ball and socket swivels or hinges made from u-brackets.  When needed, plates could be affixed to telescoping or fixed-length poles using threaded or pinned connections (using a bottom plate with a u-bracket hinge instead of a swivel will keep the pole from falling to the left or right).  The device could then be deployed to cover a window opening and quickly reduce the heat release rate of the fire (Figure A).  A single plate affixed to a pole could be deployed to cover an upper story window from an elevating platform (Figure B).  If needed, a tube, pipe, or set of clamps could be designed and mounted on a ladder apparatus to hold the device securely in place over the window.  Worried the metal plate might melt?  Bolt a piece of plywood to the fire-facing side as insulation.  Like an Apollo capsule’s ablative heat shield, it’ll still protect the plate even if it burns for a short time.  Looking for materials to experiment with?  Old traffic signs might be available from your local street department.  Ball and socket swivel mounts may be obtained from boating supply dealers.  Of course, you won’t need a contact probe, but you may want to try attaching something to the interior side of the plate to catch the window frame.  That would at least prevent the plate from sliding to the side of the opening.  Do you think some old curb feelers might do the job?  Give it a try.

Controlling the ventilation flow path to isolate the fire and potentially reduce its heat release rate is a significant operational improvement benefiting both fire victims and firefighting personnel entering a structure for search, rescue, and extinguishment,  But of equal import is the realization of the tactical advantage gained by using water to indirectly cool the heated space inside a building to make conditions more favorable for advancing maneuvers and a Direct Attack on the main body of fire.

“Fast Water” and other Indirect Cooling Methods

In some major cities, engine companies and some ladder and rescue companies have begun carrying modified navy fog applicators and similar “homemade” nozzles for cooling wind-driven fires in high-rise buildings.  These companies are charged with using these appliances to introduce a water fog or straight stream into a window on the windward side of the fire to provide indirect cooling of the interior.  The specialized nozzles are deployed from the floor below the fire and are often fitted to be hung on a windowsill to introduce water into the in-flowing air.  The wind carries the water fog or droplets from a deflected straight stream (along with the steam produced during cooling) through the burning unit and into the hallway.  There, it eliminates the blowtorch-like conditions that often prevent firefighters from advancing to the seat of the fire for extinguishment.  Some of the nozzles are designed to be extended horizontally from a window on the floor below the fire, then a stream is flowed upward into the window opening on the fire floor above.  If deflected off the ceiling inside the burning unit on the fire floor, a straight stream applied using this method can create an abundance of water spray and provide effective indirect cooling.  Of course, a fire within the reach of aerial apparatus can be cooled from the elevating platform or ladder by using a hand-held hoseline equipped with either a standard nozzle or one of these specialized nozzles.  Use of the ladder pipe would be reserved for initiation of a Blitz Attack on an upper floor of a multi-story building.

In high-rise buildings, streams used for indirect cooling improve tenability for crews on hand-held hoselines as they advance within common hallways to the seat of the fire for extinguishment.  Prompt success of such an offensive fire attack is the best way to improve life safety conditions for persons in affected portions of the building.  In noncombustible structures, occupants of compartments other than the unit that is burning can often “shelter-in-place” without a need to risk movement through hot smoke-choked hallways and stairwells during an evacuation.  In combustible buildings, the ability to get the fire knocked down quickly can improve the prognosis for a successful search and evacuation and avert a catastrophic inferno that can be fought using only defensive measures.  Being forced into a defensive-offensive strategy, a “holding action” to contain the fire and protect egress routes while an evacuation is conducted prior to extinguishing the main body of fire, or, worse yet, into a defensive strategy, will almost always put a greater number of lives at increased risk.

Indirect cooling of a wind-driven fire in a high-rise building.  N.I.S.T. tests have determined that an apartment fire originating in a bedroom and producing a heat release rate of 1 megawatt (MW) can, following ventilation under windy conditions (20-25 miles per hour or more), attain a post-flashover heat release rate of 15 to 20 MW.  Here, F.D.N.Y. firefighters position a high-rise nozzle called a “Floor Below Nozzle” (F.B.N.) to introduce water fog through a windward opening into a fire room on the floor above.  During experiments conducted on Governor’s Island in New York, F.B.N.s flowing between 125 and 200 G.P.M. in straight stream and water fog patterns “suppressed” the test fires and effectively reduced temperatures in the downwind corridor and stairway by 50%, making them tenable for firefighters.  For more information see: “Fire Fighting Tactics Under Wind Driven Fire Conditions: 7 Story Building Experiment” (2009) by Stephen Kerber and Daniel Madrzykowski, N.I.S.T. Technical Note 1629.  (N.I.S.T. Image)
Operating a Floor Below Nozzle (F.B.N.) to cool a wind-driven high-rise fire.
Indirect cooling with a straight stream “Floor Below Nozzle” (F.B.N.)  Firefighters deflect a straight stream from a “Floor Below Nozzle” off the ceiling of a burning apartment to create a water spray that is carried by the wind to cool the fire and allow advancing companies tenable passage to complete extinguishment and a primary search.
A pre-connected navy nozzle with applicator.
A pre-connected navy (military/Coast Guard) nozzle with applicator and fog tip can be deployed quickly to provide indirect cooling of an interior building space.  The length of the applicator is advantageous, allowing a nozzle operator to place the tip in an otherwise inaccessible location.  It can be inserted through nearly any opening, existing or firefighter-created, to reach heated space or fire.  It’s a dandy tool for fighting vehicle fires too!
Navy fog tip for firefighting.
Flowing about 50 G.P.M. at 100 P.S.I., this navy fog tip on a 1 1/2-inch nozzle and applicator will provide a water fog pattern about twelve feet in diameter.  Firefighters in metropolitan areas have modified these tips for use on F.B.N.s by drilling the small discharge holes to a larger size to increase the flow rate.  Nozzles for 2 1/2-inch hoselines are available with fog tips that will flow about 95 G.P.M. and produce a water fog pattern about fourteen feet in diameter.  Due to their unique indirect cooling capabilities, these nozzle/applicator/tip sets can be useful equipment for engine, ladder, rescue, and, as seen here, pumper-tanker/tender companies.
Coast Guard-style tip on an angled applicator for firefighting.
A Coast Guard-style tip on an angled applicator can quickly replace the straight applicator on the pre-connected nozzle seen in the preceding images.  Some custom-made F.B.N.s are fabricated from these applicators by mounting a metal hanger at a right angle to the pipe between the bend and the tip for draping the appliance over the windowsill of the fire room.
Indirect cooling of an attic fire.
Indirect cooling of an attic space.  Before engine companies advance hoselines for a Direct Attack on an attic fire, ladder companies may be called upon to pull the soffit/fascia materials and introduce water to reduce the heat release rate of the fire.  Deflecting a stream from a hand-held hoseline off the underside of roofing materials can provide effective indirect cooling.  Piercing nozzles, fog nails, and navy nozzles with applicators are additional options.  Engine companies can use the same technique from ground level to cool attic spaces in single-story buildings.  If needed, a ladder company can be assigned to quickly pull the soffit/fascia materials as the engine company’s nozzle crew directs their stream between each set of rafters while progressing down the length of building behind them.  For more information see: “Study of Residential Attic Fire Mitigation Tactics and Exterior Fire Spread Hazards on Fire Fighter Safety” (2014) by Stephen Kerber and Robin Zevotek, available from the U.L. Firefighter Safety Research Institute.

Most frequently, engine company personnel will be the purveyors of indirect cooling when fighting a fire inside a building.  A nozzle operator using a stream from a hand-held hoseline can rapidly cool the heated space while advancing toward the seat of the fire.  Such Indirect Attack cooling can stall the fire’s growth and “stop-the-clock”, or at least slow it down.  Steam produced by atmospheric and surface cooling, though it can temporarily impair visibility, is an ally in the smoky ballast cloud above the heads of progressing firefighters.  It can inert flame, interrupt oxidation, reduce the fuel mass fraction, and will often reduce the heat release rate until the nozzle operator can reach and extinguish the main body of fire using a Direct Attack.

The most recent research into the behavioral characteristics of growth-phase structural fires is clearly revealing the necessity of a quick application of water from a safe, frequently exterior, location to cool the heated space before proceeding inside.  Due to the rapid growth rate of today’s structural fires, every second counts.  The use of “Fast Water” cooling figuratively “resets-the-clock”, rolling it back to buy additional time by reducing the heat release rate to that of an earlier moment in the fire’s growth.  It immediately improves conditions on the interior for any fire victims still inside.  For firefighters “transitioning” to interior positions, conditions will be less stressful and there is improved likelihood of success as they make entry, cool a path to the main body of fire, and extinguish it with a Direct Attack.

The “Fast Water” Transitional Structural Attack (often being called simply “Transitional Attack”) is the tactical descendant of the first bucket brigade attack that doused a log wall to save a family’s home.  “Fast Water” cooling is initiated using a stream from a hand-held hoseline positioned at an advantageous location, usually on the building’s exterior.  In many cases, the crew preparing to enter and advance to the seat of the fire will use the stream from their line to cool and “reset” the fire before continuing to the interior.  As an alternative, a line could be deployed and operated by just a single firefighter who cools and “resets” the fire while the interior crew is preparing for their entry and advance.  This latter method will get water onto the fire more quickly.  Booster tank water is often sufficient for “reset cooling” from the exterior position.  However, a tanker/tender or hydrant supply should be secured and in use prior to the transition to interior positions.  (See the next section: Pulse/3-D Transitional Attack for an evolution of the “Fast Water” Structural Transitional Attack as it descended from the Combination Attack in many fire school programs.)

Can a “Fast Water” hoseline really be positioned and operated by just one firefighter to cool and “reset” a working fire?  Soitenly!  (Public Domain image from the 1936 Columbia Pictures short “Disorder in the Court”)
"Fast Water" cooling initiates a transitional fire attack on a structural fire.
“Fast Water” cooling.  A fire in a compartment has progressed to involve structural members and has self-vented to the exterior of the enclosure to become a structural fire.  A “Fast Water” Structural Transitional Attack is initiated to extinguish this working fire.  A firefighter using a hand-held hoseline cools the heated space from the exterior via the opening(s) where the fire has self-vented.  Meanwhile, the interior crew is preparing to enter the building to advance a line to the seat of the fire for extinguishment.  After the first line “resets” the fire and shuts down, the interior crew can proceed, using a stream from their line to continue cooling the heated space as necessary along the way.

Water applied into the heated space of a burning building instantly improves conditions therein for victims and search crews by reducing the heat release rate of the fire and slowing its forward progress.  To afford some initial protection for crews extending a primary search, at least one fire stream needs to begin the cooling process immediately upon arrival—then lines need to be advanced for the Direct Attack on the main body of fire to intercede between it and affected areas where victims may require rescue.  These two requisite tasks—water application and extension of the primary search—comprise the tactical imperative for an offensive fire attack strategy.

As companies begin advancing into the interior, traditional guidelines for initial hoseline placement to protect search and rescue and extinguish the seat of the fire still apply…

        1. The First Hoseline (the Leadoff Line) intercedes between the fire and victims, then protects egress routes including stairs, corridors, etc.  In most cases, the crew on this line can seize the opportunity to knock down the main body of fire with a Direct Attack.
        2. The Second Hoseline (the Backup Line) backs up the first line or protects a secondary means of egress, often advancing into the floor above or covering portions of the building to the rear and/or flanks of the first line.
        3. The Third Hoseline and subsequent lines supplement the initial attack positions and/or advance into previously uncovered areas including additional floors both above and below the fire and portions of the building accessible from the rear.

Nozzle operators need to always heed this fundamental concept of structural firefighting: don’t pass by fire, put it out!  Letting rooms and combustibles burn behind you while you advance toward additional fire can be the last mistake you’ll ever make.  You could become subjected to scorching heat in the fire’s ventilation flow path or trapped by rapid fire growth.  If it’s burning, cool it—get water onto any fire you encounter as fast as possible—then keep moving.  Crews following with backup lines can complete the extinguishment of any fire you’ve knocked down.

Controlling auto-exposure during an offensive fire attack.
Eliminate the auto-exposure hazard.  Fire burning on the exterior of a building (particularly from a ventilation point) and threatening to extend into new areas on the interior is known as “auto-exposure”.  To control auto-exposure prior to entry, these firefighters are quickly making a sweep of the nozzle to extinguish flames in the soffits and around second floor windows before “resetting” the fire to neutralize the threat.  They’ll then advance to the interior to complete extinguishment.  During bigger fires in larger buildings, exterior streams of a larger caliber may need to carefully maintain a continuous flow of water across the outside surfaces of the structure until the source of the auto-exposure can be cooled or extinguished.
Deploying a Bresnan cellar nozzle to cool a basement fire.
Cellar (basement) fires are best cooled and entered on the same level as the fire.  SENDING FIREFIGHTERS DOWN A STAIRS INTO THE VENTILATION FLOW PATH OF ONE OF THESE SUPERHEATED INFERNOS CAN HAVE FATAL CONSEQUENCES.  Water fog, deflected straight streams, or water spray from piercing or navy nozzles can be used to reduce the heat release rate and “reset” the fire before hoselines are advanced for Direct Attack extinguishment.   For fires in cellars that are fully below grade with no windows, walls, doors, or other access on the level of the fire, the broken stream from a spinning Bresnan cellar distributor (depicted here) can provide effective indirect cooling of the heated space prior to entry for extinguishment.  (Note: ALWAYS EVALUATE THE FLOOR FOR STABILITY BEFORE AND DURING THESE OPERATIONS!  Be particularly wary of newer lightweight construction methods and materials.  Don’t hesitate to pull everyone out if the structural integrity of the floor is questionable…IF YOU’RE UNSURE, GET OUT AND FLOW THE FLOOR!)  In this example, ladder company personnel assist the engine company by opening several small holes in the floor above the fire area for insertion of the distributor.  They’ve also remembered to close the door to the cellar to help contain the fire and reduce the heat release rate.  When applied through small holes in the floor to cool the cellar space below, water spray from piercing nozzles or water fog can be suitable alternatives for “resetting” these fires lacking horizontal access.  Learn more by reading “Understanding and Fighting Basement Fires” (2018) by Daniel Madrzykowski and Craig Weinschenk.  (Editor’s Note:  Many compartment fires in cellars, if readily accessible horizontally, can be extinguished using the Pulse/3-D Transitional Attack as an offensive option, or the Indirect (Fog) Fire Attack as a defensive option.  Commentary describing these tactics will follow in later sections.)
A Bresnan cellar nozzle.
Dig out that Bresnan cellar distributor and give it a whirl!  You can build your own extension pipe/elbow/valve assembly, or you can buy one from a vendor.  Its use doesn’t have to be limited to cellars and it will provide 23 MW or more of indirect cooling with NO NOZZLE REACTION.  Train your members to use it; then drill, drill, drill.

Hey, wait a minute.  Why are you using the term “megawatt” (MW) here?

Glad you asked.  A megawatt (MW) is a measurement of power—the rate at which energy is generated or used.  It is the equivalent of one million watts—an energy release or use rate of one million joules per second.  In the context used here, “heat release rate”, measured in megawatts, is the rate at which heat energy is generated by a fire.  The rate at which a given water flow can use (absorb) heat energy from a fire is expressed in megawatts of “cooling capacity”.  If you’re getting the idea that putting out fires is closely linked to the principles of physics, especially thermodynamics, then you’re on the right track.

Examples of Energy Release Rates Measured in Megawatts (MW)

.001 MW—a 100% efficient 1,000 watt electric baseboard heater

2 MW—a wood pallet burning

12 MW—a large furnished living room on fire

20 MW—a wind-driven apartment fire

160 MW—the reactor at Three Mile Island Unit Two after the “scram” or “trip” (dropping of control rods to stop the fission reaction) in the early moments of the 1979 nuclear accident*

1,210 MW (better known as 1.21 gigawatts)—the flux capacitor on Doc Brown’s DeLorean when traveling through time 

2,689 MW (that’s 2.689 gigawatts)—the reactor at Three Mile Island Unit Two operating at 97% of capacity moments before the 1979 accident and the “scram” (“trip”) shutdown 

10,000+ MW (10+ gigawatts)—a bolt of lightning

 * An operator error, specifically the manual override of a cooling pump to reduce the designed 1,000 G.P.M. flow of water through the reactor core to a rate as low as 100 G.P.M., led to the partial meltdown of Three Mile Island Unit Two’s uranium oxide fuel assemblies during the decay and cooldown period in the hours after the “scram” shutdown.  The same principles that apply to cooling a nuclear reactor also apply to cooling and extinguishing a fire—the flow of water must be sufficient to overcome its heat release rate.  It doesn’t matter whether it’s a fire or a nuclear reactor producing a heat release rate of 160 MW, both require a water flow of 1,000 G.P.M. to adequately absorb the energy being generated.  For details on the heat release rates and cooling issues that led to the T.M.I. 2 meltdown, see the post on this website titled Three Mile Island 40: Part One dated March 28, 2019.

Blitz Attack—Quick Cooling of a Marginal or Deep-seated Working Fire

Cool and "Reset" the Fire with a Blitz Attack

Complete Extinguishment with a "Fast Water" Structural Transitional Attack

Using a master stream device such as a deck gun to cool and “reset” a marginal or deep-seated working fire is a legacy tactic in use for over fifty years.  The Blitz Attack may be a fire chief’s only offensive option for addressing a fire reaching flashover or fully developed phase.  It is initiated with heavy stream application (usually at least thirty seconds in duration) to provide massive heat absorption as water is converted to steam.  This “reset cooling” is followed by a hand-held hoseline advance on the main body of fire to complete extinguishment, essentially using a “Fast Water” Structural Transitional Attack.

Of course, buildings with questionable structural integrity should not be entered without serious risk-versus-benefit analysis.  Long-burning fires have probably weakened key portions of the involved structure and are thus candidates for a defensive fire attack strategy, not a Blitz Attack.  Buildings assembled using newer lightweight construction materials and methods are not likely to be safe for entry after a fire has progressed to the point where a Blitz Attack might be considered—so consider a defensive strategy instead.  It may be tempting to use a Blitz Attack to suppress a fire in a vacant or abandoned structure, but when no life hazard exists and there is very little property of value to save, the use of master streams should be considered defensive measures which will not be followed by advancing maneuvers to extinguish the main body of fire.

In all cases, the progress of a Blitz Attack must be monitored closely.  Adequate lead-off and back-up lines must be advanced, sufficient water supplies need to be secured, and exterior lines, including master streams, should be positioned and readied for possible use if a withdrawal is necessary.

An engine company initiates a Blitz Attack to extinguish a fire in a barn.
Softening the Target with a Blitz Attack.  An engine company leads off with its master stream device using 500 gallons of booster tank water to “reset” the deep-seated working fire in this barn (800 G.P.M. for just over 30 seconds).  Meanwhile, the remainder of the crew expeditiously makes supply hose hook-ups, dons S.C.B.A.s, and advances hand-held hoselines to complete the extinguishment of the main body of fire.  This offensive fire attack strategy succeeded by quickly cooling the fire from an exterior position with the Blitz Attack, then transitioning to interior positions to use a Direct Attack on the remaining fire.  At just 25% efficiency, application of 800 G.P.M. can provide 33 megawatts (MW) of cooling to roll back the progression of such a blaze.  This barn was repaired, repainted, and decorated.  It still stands strong over twenty-five years later.   (Image by Ken Dyer)
IFSTA’s “Structural Fire Fighting Initial Response Strategy and Tactics” Second Edition (2017) is among the first books to include modern fire behavior and a “Fast Water” Structural Transitional Attack in its text, though the discussion of both is limited and brief.  They should have included a “Fast Water” Structural Transitional Attack on the cover too, before that crew gets scorched and auto-exposure burns the building down!  Unfortunately, training manuals for teaching doctrine are often the last places a student will find the incorporation of new technology… 
…but the new edition is a little better.  Supplement this book with the materials available on the web and you’ll be on the cutting edge of progress.

Be current on the latest in structural firefighting and fire behavior innovations by checking these web resources regularly…

Beware of Dogma/Doctrine

The modern vocation of firefighting has as its foundation scientific principles— chiefly those of physics including thermodynamics and applied sciences including hydraulics.  These “fire sciences” are frequently the antithesis of fire service “dogma”—the long-standing myths that, over time, have ascended to the status of well-entrenched habits and traditions.

Recent research is clearly demonstrating that depriving a fire of fresh air is the most effective ventilation method for reducing its heat release rate and spread.  Furthermore, these studies prove that an additional reduction in the heat release rate is achieved by the indirect application of water both before and during advancing maneuvers toward the seat of the fire.  Prompt introduction of water into the heated space enhances safety, interrupts exponential growth of the fire, and improves the probability of a successful Direct Attack on the main body of fire.  Fast indirect cooling and opening up only after water is flowing onto the main body of fire are offensive imperatives for fighting today’s hydrocarbon-fueled structural fires.  It’s a fact, despite dogmatic rhetoric to the contrary.

Skeptical that indirect cooling should be used during an offensive fire attack?  Well, surprise!  It’s been part of offensive tactics for a long time.  Click the red box to see a chart that maps it all out (PDF file).  We’ll take a more detailed look at the contents a little later on.

Administrators, fire officers, and firefighters must beware of flawed fire service doctrine.  If heeded as a set of inflexible rules, it can impede the formulation of a sound operational plan.  Failure to conform oneself to some of these “absolutes” can sometimes render the “transgressor” a prime target for disciplinary action or, at the least, an unrelenting boorish rebuke by his/her peers.  As an individual, one must be courageous and remain informed and prudent in judgment in order to make decisions based upon facts, not peer pressure, dogma, or rigid doctrine.  Within a fire department, a progressive culture that embraces innovation and carefully introduces suitable new (or applicable legacy) methods and techniques into its operations is often rewarded with a safer fireground, more favorable outcomes, and improved esprit de corps among its members.  Lead by example—keep an open mind and teach younger firefighters how to weigh the pros and cons of applicable new ideas.  Discriminate judiciously between that which is just something new for purchase and that which is an authentic and potentially beneficial innovation.  Avoid surprises, keep everyone informed to lessen the inevitable “ordeal of change”.  And remember, flexible policies that encourage competent decision making and practical solutions can go a long way toward motivating, developing, and retaining some of a department’s best leadership talent.

Firefighters initiate a Blitz Attack to cool and "reset" a deep-seated working fire.
It’s okay for an engine company to take a position in front of the fire building.  An engine company initiates a Blitz Attack using their deck gun (deck pipe) to cool and “reset” a deep-seated working fire.  Despite a low application efficiency (using 25% for this example), this master stream equipped with a 1 3/4″ nozzle tip flowing 814 G.P.M. at 80 P.S.I. can provide 33.4 megawatts (MW) of cooling.  Widespread fire service doctrine reserves the front of the fire building for placement of a ladder company.  However, the great advantage gained by stopping the first-in engine in front of the building to quickly dump its tank water onto the fire justifies this maneuver.  After the fire is “reset”, the pumper can easily be moved forward to allow space for the aerial apparatus.  The crew can continue to set up for an advance on the seat of the fire for extinguishment, but they make entry only after a supply line has been connected to the repositioned engine and charged.
A portable master stream device operating with a set of smooth bore nozzles.
Know the capabilities and limitations of your portable master stream devices.  The portable multiversal allows placement of a master stream at nearly any flat level location.  During efforts to save burning churches, McAniff describes their deployment in the aisles for cooling the heavenly reaches above.  They can be very versatile.  However, for Blitz Attack use, these devices have little advantage over hand-held hoselines.  At 502 G.P.M. (1 3/8″ tip @ 80 P.S.I.), 20.6 MW of cooling is provided at the 25% efficiency that is likely from a master stream.  Compare this to the performance of a 2 1/2″ hoseline flowing 266 G.P.M. from a 1 1/8″ tip.  It can be used by two firefighters to achieve 21.8 MW of cooling in the heated space (50% efficiency when applying a straight stream from a hand-held line).  Achieving greater cooling from the portable master stream would require a larger nozzle tip and the time-consuming addition of a second supply hose.  When using booster tank water, remember that as much as one hundred gallons can be left stranded and useless in the hose when the tank goes empty.  The deck gun (deck pipe), on the other hand, has the advantage of flowing nearly all of the tank capacity into the heated space.  But, then again, if you can’t get the apparatus in a good position to use the deck gun and manpower is sparse, one firefighter can get a portable multiversal in position and cool a fire with great effect.  It’ll do in a pinch.
Firefighters initiate a "Fast Water" Structural Transitional Attack to "reset" and extinguish a fire in a dwelling.
A well-conducted “Two-minute Drill” can sometimes provide more effective cooling than a master stream attack.  When cooling a structural fire with good access from the ground level, an athletic crew operating a hand-held hoseline flowing 210 G.P.M. or more can outperform a master stream with twice the flow.  They have the advantage of applying water from multiple angles to not only “reset” the fire on the interior, but also to stop any extension by auto-exposure.  In this example, the fast-moving crew may reposition the line eight times or more to stop the forward progress of a runaway fire:  1) Cool the visible fire through the garage door opening.  2) Sweep the soffits above the garage doors to prevent auto-exposure extension.  3) Sweep the walls and soffits of the house above the fire area.  4) Cool visible fire through the side door.  5) Cool visible fire through the garage window.  6) Cool the heated space in the loft and sweep the gable end exterior surfaces.  7) Cool visible fire through windows or other openings on the rear, then sweep the walls and soffits as needed.  8) From a position to the rear, sweep the walls and soffits of the house above the fire area.  (Note: These steps are merely an example of how a crew might make their way around a fire building.  Circumstances may require a different sequence, such as application of water to address an auto-exposure threat prior to the cooling of the interior areas.)  An energetic crew can often complete this cooling evolution within just two minutes, requiring only their engine company’s booster tank water as a supply (500+ gallons).  Additional water from hydrants or tanker/tenders is used to supply all hoselines advanced to complete containment, extinguishment, and overhaul of a fire similar to this.

There is currently a widespread perception that the use of “reset” cooling represents abandonment of fire service doctrine dictating that, in order to facilitate fire containment and protect search and rescue, fire attack must occur from the “unburned side”—the portion(s) of the building into which fire has not yet extended.  This is not the case.  Isolation of a fire both through the use of tactical ventilation methods and traditional hoseline placement that intercedes between it and imperiled victims and property is a critical component of today’s offensive fire attacks.

Attack positions on the “unburned side” of the fire will often be the most favorable, but they are no longer the only option.  Recent fire behavior experiments have debunked the founding dogma behind “unburned side ” doctrine—that hose streams directed into heated spaces from exterior positions will “push fire” into unburned areas.  Research now proves that cooling of the heated space and getting water onto the main body of fire in a timely manner is of greatest importance, even if water must be flowed into a ventilation point—attacking the fire from the “burned side”.

“Reset” cooling interrupts the rapid growth of modern fires—buying time for Direct Attack and search and rescue efforts.  Fast water quickly rolls back the enormous heat release rates of today’s hydrocarbon-fueled fires to improve the tenability of positions on the “unburned side” for both firefighters and fire victims.  The indirect cooling provided by a hose stream used to “reset” a fire improves conditions instantly within the burning space and adjacent areas.  The reduction in the fire’s heat release rate often gives firefighters a window of opportunity for maneuvers toward the main body of fire from the “unburned side” of the structure for containment and extinguishment—an opportunity that might not otherwise be realized.  A fear of “pushing fire” into unburned portions of the building should no longer prevent firefighters from engaging in the fast application of water to cool and “reset” a fire at the earliest opportunity.

The R.E.C.E.O.-V.S. and S.L.I.C.E.-R.S. mnemonic acronyms are considered by many to denote a set of firefighting rules.  As a result, one or both are vigorously defended by some and criticized by others.  They’ve been perceived to be doctrine.  This is unfortunate.  They’re meant to be guidelines to teach a basic fire operations sequence—that’s all.  If the opportunity to rescue a victim or victims presents itself, you conduct the rescue.  It could be that a rapidly progressing fire will need to be cooled without delay so members can reach visible victims and pull them to safety—so you do it.  Frequently, a prompt offensive fire attack eliminates the fire and is the best assurance of occupant and search crew safety—so get it done.  It’s often just that simple.  Please remember that in the case of the mnemonic acronym S.L.I.C.E.-R.S., it’s not a word in a game of scrabble where you must get all the letters in the correct order to get all the points—it’s just a useful reminder to help you recall the sequence of tasks in a process.

SLICERS mnemonic for transitional fire attacks.
Following research into modern fire dynamics, the S.L.I.C.E.-R.S. mnemonic acronym was developed as a guideline for a sequence of tasks to be performed when using an offensive strategy and transitional fire attack tactic to extinguish a fire in a building, particularly in a dwelling.

To learn more about “S.L.I.C.E.-R.S.”, be certain to view the “Principles of Modern Fire Attack: SLICE-RS” video produced by the International Society of Fire Service Instructors (ISFSI).


Compartment Fire Offensive Fire Attack Tactics

—Pulse/3-D Transitional Attack

Pulse/3-D Transitional Attack

Upon arrival at a fire scene, does your fire department differentiate between a compartment fire and a structural fire?  Do you employ a different set of tactics for each?  Is your fire department training, drilling, and equipping its companies to safely and effectively extinguish compartment fires?  Do you have pre-connected hoselines equipped with combination nozzles capable of gaseous layer cooling for use during compartment entry, the advance to the seat of the fire, and extinguishment (less than 150 G.P.M. to allow short pulse action, and operating at a minimum of 100 P.S.I. for proper droplet production)?  Does your department understand extreme fire behavior?  What is a fuel-controlled (limited) fire?  What is a ventilation-controlled (limited) fire and why is it so prevalent today?  Do you understand the impact of ventilation on a compartment fire?  Are you curious about tactics used in other countries?  How are pulses of water fog used to cool and raise the gaseous layer inside a burning compartment during the advance to the seat of the fire?

For many, the Pulse/3-D Transitional Attack may be reminiscent of the Combination Attack, a tactic widely used to extinguish both compartment and structural fires from the 1950s through the 1980s.  Because water fog is often applied through the door opening while entering the building, both could be classified as a type of transitional fire attack.

The Combination Attack cools the path of advance to the main body of fire using a liberal application of water fog into the heated space.  It includes the application of water to heated surfaces (ceiling and walls) as well as the gaseous layer to provide indirect cooling.  A Direct Attack extinguishes the main body of fire, then hydraulic ventilation using water fog finishes the job.  During the advancing maneuvers of the Combination Attack, water fog vaporizes to massive amounts of steam as it absorbs heat, often reducing the heat release rate of the fire dramatically, but sometimes creating visibility problems severe enough to mask its location.

For most fire departments, a straight stream modification of the Combination Attack remains in use today, particularly to fight structural fires.  The majority of fire training programs generally abandoned water fog use during the 1980s and began teaching this revised attack tactic.  This straight stream attack completes extinguishment with a fundamental Direct Attack—the application of water directly onto the seat of the fire.  With this change in curriculum, the basic extinguishing task known as a Direct Attack was formally elevated to a tactic.  A key component of this amended tactic is still indirect cooling, but now using straight streams to cool heated surfaces during the advance to the seat of the fire—the cooling of the gaseous layer becoming only a side effect.  So then, the Direct Attack “tactic” utilizes both the Direct Attack (to extinguish the seat of the fire) and what many call the Indirect Attack (indirect cooling) tasks as components of its process.  It’s no wonder firefighters are confused!  (In the future, you’ll have a better understanding of fire attack tactics if you think of the Direct Attack and Indirect Attack as water application tasks, not necessarily tactics in their own right.  We’ll gather ’round the campfire and clear this up in the next section: Indirect “Fog” Attack.)

Like the Combination Attack, the straight stream method of indirect cooling produces an abundance of steam as heat is absorbed and water is vaporized (despite myths to the contrary).  Because this straight stream attack applies water only to heated surfaces and the fuel at the seat of the fire, it is two-dimensional in nature.  Yet, the steam produced by cooling can have some desirable three-dimensional effects in the atmosphere of the heated space, particularly by reducing the overall heat release rate of the fire.  Most recently, the “Fast Water” cooling technique has been added to this attack to rapidly reduce the heat release rate of the fire before an advance to extinguish it commences.  This quick application of water helps to forestall and turn back (“reset”) the three-dimensional growth of a structural fire.  The term “Fast Water” Structural Transitional Attack is used here to describe this latest incarnation of what began as the Combination Attack.  The “Fast Water” Structural Transitional Attack is often the “go-to” tactic when an offensive fire attack strategy is adopted for a working structural fire.  It is also the follow-up tactic for extinguishment when a Blitz Attack is used to cool and “reset” a deep-seated or marginal working fire.

Fire dynamics and behavior: Exothermic Reaction.
A fire is an exothermic reaction.  It releases energy into its surroundings.  We describe this energy production as “heat release rate” and express it in watts, a quantity of radiant flux (energy emission) equaling one joule per second.  A fire with a heat release rate of one megawatt (MW) emits one million watts of energy, equal to one megajoule (MJ) of energy per second.
Fire dynamics and behavior: Endothermic Reaction.
Applying water to a fire creates steam.  As water is vaporized to steam, it absorbs energy, specifically heat energy, from its surroundings.  This process is an endothermic reaction.  It is how fires are cooled and extinguished with water, regardless of the nozzle, stream, or attack method used.

The production of steam is essential to reducing the heat release rate of a fire.  Yet, it often creates problems for firefighters as they struggle to complete its extinguishment.  Because nearly all of today’s fires beyond the incipient phase are in a ventilation-controlled (limited) state, “opening up” to improve visibility could lead to unexpected and catastrophic consequences.  The urge to ventilate to relieve steam and smoke accumulations could provide oxygen to shielded or yet-to-be-located fire.  The result could be an extreme fire behavior event such as a flashover.

You’ll recall that a structural fire, though burning in a ventilation-controlled (limited) state, has typically vented to the exterior of a building.  We’ve learned that controlling the ventilation flow path and initiating indirect cooling with water are effective measures when using an offensive strategy to extinguish these structural fires.  But what about a fire in a closed space, a fire that involves mostly furnishings and other contents and has not yet vented to the exterior—a compartment fire.  How should we address a compartment fire?

Firefighters can have a significant advantage when fighting a compartment fire.  Because it is unvented, its growth can often be slowed by prudent management of the ventilation flow path.  And, because it has not yet burned structural components of the building, collapse is less of a concern.  But firefighters and fire officers must possess the skill and knowledge to extinguish such a fire without allowing it to evolve into an extreme fire behavior event.  They must be familiar with the methods used to cool and extinguish these fires in closed spaces.

Indiscriminate indirect cooling of a compartment fire.
The liberal flow of water fog or straight streams onto heated surfaces produces massive amounts of steam as the heated space is cooled.   The lowering of the neutral plane to near floor level may render firefighters unable to locate and extinguish hidden or shielded fire.  Ventilation could increase the heat release rate of the fire as oxygen becomes available to fuel that has not been subjected to cooling by steam or direct water application.  An extreme fire behavior event such as flashover could result if ventilation is not carefully controlled.

The Pulse/3-D Transitional Attack tactic is more methodical than its predecessors.  It was developed specifically for fighting ventilation-controlled fires in compartments when using an offensive strategy, predominantly during the incipient phase and growth phase.  The ventilation flow path is assessed, controlled, and manipulated.  Firefighters use bursts of water fog to cool the gaseous layer (which often raises the neutral plane to improve visibility) while making entry and advancing to the main body of fire.  Water is applied carefully into the gaseous layer with intent and purpose to produce a “dry steam”—one which does not condense on cooler surfaces inside the compartment.  A Direct Attack then completes extinguishment of the seat of the fire.  This is precision firefighting.  There’s no bustin’ in the door, shatterin’ the windas, and blowin’ everything to smithereens with hundreds of gallons of water being sprayed willy-nilly throughout the place.  Thus, the Pulse/3-D Transitional Attack and water fog are heresy to the dogmatic culture of American firefighting.  American firefighters seem to hate it.  It’s hard to know why.  There’s no more intimate way to extinguish a fire.  Maybe that’s it—fear of intimacy.

Fire dynamics and behavior: The neutral plane, thermal ballast, and the Pulse/3-D Transitional Attack.
The neutral plane is the line of demarcation between fresh air flowing into a compartment (green arrows) and thermal ballast, the superheated smoke and unburned fuel flowing out of the compartment (orange arrows).  When the neutral plane “banks down” to near the floor level, firefighters advancing hoselines and conducting a primary search can be subjected to dangerously intense heat and near zero visibility.  Under such conditions, fire and fire victims may go unlocated and firefighters can be burned.
Firefighters use a Pulse/3-D Transitional Attack to cool and extinguish a compartment fire.
Short bursts of water fog expand in volume 1,700 times as they vaporize to steam in the hot gaseous layer above these advancing firefighters.  The absorption of heat from the thermal ballast (smoke and fuel) during this conversion is so great that the gaseous layer contracts in volume due to the cooling.  This process temporarily raises the neutral plane.  Additionally, the short pulses of fog prevent rollover flaming and have the effect of cooling the compartment by inhibiting the transfer of convective and radiant heat by the ballast.  The nozzle operator is careful to apply water fog only into the gases and avoids wetting walls and ceilings.  In return, firefighters experience improved visibility and safety from flashover as they advance to the seat of the fire for a Direct Attack.
Fire dynamics and behavior: Thermal Ballast with Exothermic Properties
The cloud of smoke and unburned fuel from a fire, the ballast, exhibits exothermic properties as it releases heat energy into its cooler surroundings.  It possesses the capabilities of extending the fire and its effects to previously unaffected areas.
Fire dynamics and behavior: Thermal Ballast in an Endothermic State
During the advance to the seat of the fire, pulses of water fog applied into the ballast cloud are vaporized to steam to provide indirect cooling.  This process converts the ballast from a heat-releasing exothermic state into a beneficial heat-absorbing endothermic state.  The ballast will continue to absorb heat energy from its surroundings as long as its endothermic properties are maintained with regular use of pulsed water fog cooling during the maneuvers toward the seat of the fire.
Cutaway view of a fixed-pressure (automatic) combination nozzle constructed with a slide valve.
Using a combination nozzle with a slide valve instead of a ball valve can improve the efficiency of pulsed water fog application.  Slide valve nozzles equipped with a trigger allow the operator to apply quick bursts of water fog into the heated ballast cloud of smoke and fuel to raise the neutral plane and improve visibility.  A minimum nozzle pressure of 100 P.S.I. is required to produce the proper droplet diameter (one millimeter or less) necessary for cooling the gaseous layer during door entry and advance to the seat of the fire.
Firefighters initiate a Pulse/3-D Transitional Attack on a growth-phase compartment fire.
To initiate a Pulse/3-D Transitional Attack on a growth-phase compartment fire, the nozzle operator floats two short pulses of water fog into the overhead space just outside the top of the door to cool and dilute gases that may have accumulated there.  The opening of the door is timed to coincide with this application so that any hot gases that escape flow into the water fog.  With the door slightly open, there is a rapid visual evaluation of conditions inside while a long pulse of water fog is applied to begin cooling the gaseous fire.  The door is then closed while the crew makes final preparations for entry.  They’ll apply short pulses of water fog into the ballast cloud to maintain it in a fuel-diluted endothermic state while entering and maneuvering toward the seat of the fire, which they’ll extinguish with a direct application of water onto the burning bed of fuel.  To reduce flammable gas production during their advance, penciling (a burst of a straight stream) can be used to cool pyrolyzing surfaces, but at the expense of some visibility.  The Pulse/3-D Transitional Attack is effective when addressing a fire in its three-dimensional gaseous state within an enclosure measuring up to 750 square feet in area with a ceiling approximately 8 feet high.
Extinguishing the main body of fire using a Direct Attack during a Pulse/3-D Transitional Attack.
The Pulse/3-D Transitional Attack is an effective tactic for containing and extinguishing compartment fires, particularly when the seat of the fire is shielded or hidden.
Pulse/3-D Transitional Attack to cool and extinguish a compartment fire.
A Pulse/3-D Transitional Attack in motion.  Firefighters use short pulses of water fog to cool the thermal ballast and raise the neutral plane during the advance toward the main body of fire, then use a Direct Attack with a straight stream for extinguishment. (Click image to restart GIF animation in new window.)
Pre-connected hoseline for firefighting.
A 1 3/4-inch pre-connected hoseline equipped with a fixed-pressure (100 P.S.I.) combination nozzle is suitable for the Pulse/3-D Transitional Attack. This particular “automatic” model allows the nozzle operator to throttle the flow using the nozzle’s ball valve.  A coil spring maintains a constant 100 P.S.I. nozzle pressure by controlling the size of the discharge orifice in response to the flow.  Other models are equipped with dials for adjusting the flow, allowing the operator to use a lower setting for indirect cooling with water fog and a higher setting, if needed, for the straight stream Direct Attack on the main body of fire.  For all models, the flow is limited to the nozzle’s designed maximum, provided, of course, that that maximum is being pumped through the line by the driver-operator of the pumping apparatus.
A pre-connected hoseline with a fixed-flow combination nozzle.
This pre-connected hoseline fitted with a fixed-flow 200 G.P.M. @ 75 P.S.I. combination nozzle would find best use fighting a structural fire; it’s not the set-up one would desire for fighting a compartment fire using the Pulse/3-D Transitional Attack.  At flow rates exceeding 150 G.P.M., operators will find it nearly impossible to open and close the nozzle valve fast enough to create the pulses of water fog necessary for proper gaseous layer cooling.  Also, the 75 P.S.I. nozzle pressure is inadequate for the small droplet production needed to effectively absorb heat from the smoke and fuel ballast while advancing to the main body of fire.  Lacking appropriate equipment, knowledge, and skills, you’re left to the sloppy business of fighting a compartment fire as if it’s a structural fire.  There is a better way.

You’ll recall the accomplished fire officer who possessed vast experience fighting and directing forces at structural fires.  He asked an acquaintance who happened to be renowned for his knowledge of ventilation-controlled fires, “How should I address a compartment fire.”  The acquaintance told him to say to the compartment fire, “I’d like to get to know you.”  And the fire officer and the compartment fire thereafter began an intimate relationship.

“3D Fire Fighting: Training, Techniques, and Tactics” (2005) by Paul Grimwood, Ed Hartin, John McDonough, and Shan Raffel introduces American firefighters to the science of fire behavior, extreme fire behavior (flashover, backdraft, etc.), tactical ventilation, and compartment fire extinguishment.  It and co-author Paul Grimwood’s “Euro Firefighter” (2008) may be the most enlightening firefighting books you’ll ever read.  “3D Fire Fighting” includes a CD with videos of fire behavior demonstrations and compartment fire attack tactics.

Anything you can find by the authors of 3D Fire Fighting: Training Techniques, and Tactics is absolutely worth the investment of your time.  There are various videos online and be certain to check Grimwood’s EuroFirefighter and Hartin’s Compartment Fire Behavior Training websites for more great information.  Hartin is involved with the UL Fire Safety Research Institute, whose projects and training programs you should be following with unmatched dedication.


Compartment Fire Defensive Fire Attack Strategy

—Indirect “Fog” Fire Attack

“In battle, there are not more than two methods of attack—the direct and the indirect; yet these two in combination give rise to an endless series of maneuvers.” 


(The Art of War)

Indirect "Fog" Fire Attack

Has your fire department ever heard of using Indirect “Fog” Attack as a defensive tactic for extinguishing compartment fires?  What is it?  When should it be used?  Have you ever been trained on its use?  Have you tried it on live fire drills?  Used it on a real fire?

When questioned on the matter, most firefighters are confident that they, at some point during their training, learned the Indirect Attack.  This is certainly true.

When questioned further, these same firefighters aren’t so sure that they ever learned the Indirect “Fog” Attack.  Unless they’ve taken a very progressive compartment fire extinguishment course (or were a navy firefighter), we can be pretty certain that they have not been taught the Indirect “Fog” Attack—and it’s an enormous oversight.

Before discussing the Indirect “Fog” Attack in detail, let’s try to better understand the Indirect Attack in all its variations.  We’ll begin with definitions for the Direct Attack and the Indirect Attack.

DIRECT ATTACK—the task of applying water from a fire stream onto the pyrolizing fuel of the fire bed (seat of the fire/main body of fire).  The water reduces the heat release rate of the fire as it absorbs heat from the fuel and is converted to steam.  Secondarily, the steam interrupts the oxidation of fuel and continues to absorb heat as a component of fire ballast (smoke).  These reactions extinguish the fire.

INDIRECT ATTACK—the task of applying water from a fire stream into the heated space to cool fire ballast (smoke) and/or heated objects (ceiling, walls. etc.) by absorbing heat and converting water to steam.  The steam interrupts the oxidation of fuel and continues to absorb heat as a component of fire ballast (smoke).  Secondarily, the effects of the steam can reduce the heat release rate of the fire, sometimes extinguishing it, especially in closed spaces.

You may have noticed that the Direct Attack addresses the fire from mostly a two-dimensional perspective (the surface of the fuel) and that the Indirect Attack tackles its third dimension—the heated space including the ballast.  In nearly all cases, the Direct Attack is the task of extinguishing the fire, the Indirect Attack cools the path for the advancing maneuvers needed to do it.

Imagine we have an evening get-together around the campfire.  The fire glows and crackles inside a steel fire ring.  Between the tall tales of firefighting glory and funny stories of everyday life, maybe we toast a few marshmallows.  Surely, nothing beats campfire food and the company of friends.  Then, after roasting our weenies and warming our buns, it’s time to extinguish the fire for the night…
Direct Attack- water is applied to the pyrolyzing fuel (the wood) and the heat release rate immediately plummets as the water absorbs heat and is converted to steam.  Also, the steam interrupts the oxidation of fuel and cools the cloud of smoke and fuel (ballast) rising from the fire ring.  The fire is extinguished.
Indirect Attack- water is applied to the steel fire ring from which it absorbs heat and is converted to steam.  The steam interrupts the oxidation of fuel, cools the cloud of smoke and fuel (ballast), and reduces the heat release rate of the fire.  It may extinguish the fire, but you’ll probably have to finish it off by directly dousing the logs.  Goodnight.

You’ll also notice that the Direct Attack and Indirect Attack are tasks.  This is important.  It means that some (most) tactics may include both Indirect and Direct Attack tasks.  Understand too, the hierarchy of incident management here—there is one fire attack strategy as an operational framework, with one or more tactics implemented to fulfill strategic goals, by completing one or more tasks for each tactic used.

You’ll see in the following chart that you probably use Indirect Attack more often than you realized.  Indirect Attack has long been a cooling skill used by nozzle operators to facilitate hoseline advancement and fire containment.  Fire dynamics research is providing evidence that Indirect Attack water application is often the fastest and safest way to initiate a reduction in the heat release rate from a building fire.  Have a look at how Indirect Attack and Direct Attack tasks are partners in fire suppression…

Click the image to view and download the PDF file.

The chart clearly reveals that to extinguish building fires, Direct Attack is facilitated by the cooling effects of Indirect Attack.  The two are a routine task set for every tactic except one—the Indirect “Fog” Fire Attack.

The Indirect “Fog” Attack seemed to be magic to firefighters in the 1950s and 1960s.  You know, something so amazing that a wizard must surely have bestowed it upon society.  Well, if it was a wizard, the man behind the curtain was Lloyd Layman.  In his 1952 book Attacking and Extinguishing Interior Fires, Layman encouraged American firefighters to adopt the application of water fog as the primary means for extinguishing fires located inside buildings.

A man way ahead of his time, Layman advocated keeping a ventilation-controlled fire in that same state during extinguishment (he also advocated control of the ventilation flow path and many other concepts worth revisiting).  A compartment (a closed building or portion thereof) involved in fire was to be kept as airtight as possible, and extinguishment would be accomplished by opening a door (or window, etc.) and quickly introducing a water fog into the hot atmosphere inside using a rapid circular motion of the nozzle to produce an abundance of “wet steam”.  The enclosure was again made as airtight as possible for at least a minute while the steam absorbed heat from the ballast (smoke, fuel vapor, etc.) of which it was now a component.  The ballast cloud, now cooled below ignition temperature and more massive, would continue to absorb heat.  The steam would also interrupt oxidation of pyrolyzed fuel.  The heat release rate would crash, and the fire was usually extinguished.  Then the compartment could be opened up for overhaul and a Direct Attack could extinguish any fire that might remain.  The heat absorbed by the ballast leaves the building as it is ventilated.  This was the Indirect “Fog” Attack—a cure-all for extinguishing fires in unoccupied compartments.

Thermal Ballast during an Incipient-phase Fire
Incipient Phase- an abundant supply of oxygen (shown here as green diamonds) and hot fuel (red diamonds) react to cause combustion and an increase in the heat release rate, thus vaporizing more fuel from pyrolyzed combustibles and allowing the fire to enlarge and spread.  The fire is in a fuel-controlled (fuel-limited) state.  As the fire progresses into a growth phase, smoke (black pentagons) and any unburned fuel will begin to accumulate near the ceiling as a heat-absorbing thermal ballast.  Even when not flaming, the hot ballast can transfer its energy to new areas by convection and radiation to spread the fire.
Thermal Ballast during the Initial Decay (Smoldering) Phase
Initial Decay (Smoldering) Phase- as the supply of oxygen (green diamonds) is consumed by the growing blaze and the density of the ballast cloud increases, the fire enters a ventilation-controlled (ventilation-limited) state.  Oxidation of the fuel has been interrupted.  Soon, often within minutes, the oxidation is insufficient to support combustion, the heat release rate drops, and the fire begins smoldering.  The hot ballast containing smoke (black pentagons) and unburned fuel (red and dark red diamonds) fills the compartment needing only an inflow of fresh air to renew growth of the fire.  The conditions may exist for an extreme fire behavior event.  Rapid fire progress, initiated by a renewed oxygen supply, could lead to an expeditious flashover of the compartment.  A backdraft explosion could result if gravity currents carry an inflow of oxygen to a fuel-rich smoldering fire.  A smoke explosion could occur if a flammable mixture of fuel and oxygen is transported by air currents to, or is otherwise subjected to, an ignition source within the building.
Thermal Ballast following an Indirect "Fog" Attack
Effect of the Indirect “Fog” Attack- Oxygen (green diamonds) will enter the compartment as soon as an opening is made for the application of water fog.  (Best results are achieved by keeping the opening as small as practicable.)  Immediately, water fog must be applied into the fuel-rich gaseous layer, where it will vaporize into steam (white ovals), expanding as much as 1,700 times its liquid volume as it absorbs heat from the hot ballast.  Water fog will also contact hot surfaces within the compartment and be converted to additional steam.  (There’s no need to “aim” at these surfaces, they’ll receive water fog incidentally during application.)  The mass of the steam quickly dilutes the mass of any oxygen which may be in-flowing during the water fog application.  In addition, the steam becomes part of the ballast cloud and cools it, often below the auto-ignition temperature of the constituent fuel gases.  The ballast, due to its decrease in temperature and increase in mass, will begin creating a thermal equilibrium in the compartment as it absorbs more heat.  Most importantly, the dilution of the ballast with steam reduces the fuel mass fraction below the minimum required for ignition and an explosion.  Following water fog application, closing the compartment for at least one minute retains the ballast cloud inside and assures completion of these functions.  This technique, key to the success of the Indirect “Fog” Attack”, reduces the risk of extreme fire behavior events as firefighters subsequently vent the ballast to the exterior and enter the compartment for final extinguishment and overhaul.

Steam produced by the Indirect "Fog" Attack reduces the fuel mass fraction to prevent ignition of a smoldering-phase fire.

In 1959, Keith Royer and Floyd W. Nelson in Water for Fire Fighting (Rate-of-Flow Formula) advocated an energetic clockwise circular motion for the nozzle and stream when applying water fog.  While using this clockwise motion, they observed that heated gases, smoke, and flame were driven away from the nozzle operator and that the steam rolled to quickly and efficiently extinguish the fire. They noticed the opposite to be true when using a counterclockwise motion of the nozzle.  Said Royer and Nelson, “Several attempts have been made by qualified people to explain this phenomenon…no satisfactory answer or explanation has been provided.”  See, it is the work of a magic wizard!

Following experiments conducted by the National Institute of Standards and Technology (N.I.S.T.), Joseph M. Willi, Daniel M. Madrzykowski, and Craig G. Weinschenk reported in Impact of Hose Streams on Air Flows Inside a Structure (2016) that, “…there were no statistically significant differences in the average measured air velocity between the clockwise and counterclockwise nozzle movement patterns”.  Okay, no magic.

An Indirect "Fog" Attack to extinguish a smoldering-phase compartment fire.

An Indirect "Fog" Attack to extinguish a smoldering-phase compartment fire.

Hydraulic ventilation
Hydraulic ventilation using a cone of water fog as a fan is an effective way to remove ballast from the interior of a structure following extinguishment of a compartment fire.  From inside the building, the operator positions the nozzle three to six feet away from a window, door, or other opening, then fills about 95 percent of the opening with a 55-to-60-degree cone of water fog (without hitting the edges) to blow the smoke-filled air to the exterior.  Hydraulic ventilation can be used to quickly clear interior spaces following any fire attack.  Water fog can even be used like a fan to manipulate the ventilation flow path and clear egress routes of smoke to help prevent panic.
Controlling the Ventilation Flow Path using Water Fog (Hydraulic Ventilation)
Reversing the ventilation flow path with water fog draws smoke, heat, and gases back toward the compartment of origin for ejection from the structure.  Firefighters positioned at doors and windows can manage fresh air introduction (green arrows) to rapidly clear hallways, stairwells, and other affected spaces.  Because the hoseline used for extinguishment can often be retasked to begin hydraulic ventilation as soon as the fire has been knocked down, any delay that might be incurred by assigning later-arriving companies to deploy mechanical fans or other measures is nullified.  Confidence can be restored immediately to the occupants of the building, regardless of whether they are seeking to evacuate or shelter in place.

Many fire departments began taking Lloyd Layman’s advice.  They purchased vehicles equipped with high-pressure pumps, hose reels, and specialized nozzles to produce a high-efficiency water fog consisting of very small droplets.  Royer and Nelson suggested that for greatest effect, droplets no larger than 0.33 millimeter must be used to provide maximum surface area for the absorption of heat and conversion of water to steam.  These new fire trucks, equipped with all the high-pressure hardware, easily met that standard.

Fixed-pressure (Automatic) Combination Nozzle
Combination nozzles operated at a minimum nozzle pressure of 100 P.S.I. produce droplets with a diameter of 1 millimeter or less. This size is the maximum acceptable for water fog intended to cool a fire’s gaseous layer.  High-pressure systems using gun-style nozzles were often operated at 600 P.S.I. to easily produce high-efficiency droplets of 0.33 millimeter diameter or less.

Firefighters in many areas used the Indirect “Fog” Attack as the go-to tactic at a majority of fires to which they responded.  The fire was out in minutes, less than fifty gallons of water was used to extinguish a living room or kitchen fire, and the crew remained outside of the burning area to do it all.  It seemed to be…magic.

Chief Edward P. McAniff in Strategic Concepts in Fire Fighting recognized the significance of the Indirect “Fog” Attack tactic and created a fifth fire strategy for its use.  McAniff saw the tactic demonstrated while he was in command of the firefighting school at Pearl Harbor from 1944 to 1946, before Layman had popularized it.  He described the reaction to the attack, “…spectators would gasp at the effectiveness of this method of extinguishment.”  McAniff embraced it as the tactic for a unique defensive strategy for fighting fires in the initial decay (smoldering) phase within closed-up buildings when the concern for backdraft and smoke explosion is a critical limiting (strategic) factor.  McAniff cites a second critical strategic factor—no one is inside the structure.  These factors convinced McAniff that Indirect “Fog” Attack should be used conservatively and only within the framework of a defensive strategy.  In the book, he includes case studies of actual incidents in large multi-story commercial buildings where well-coordinated Indirect “Fog” Attacks were used to extinguish fires in the initial decay (smoldering) phase.  One smoldering fire may have been burning for days—just waiting to go boom when someone opened up.

“Strategic Concepts in Fire Fighting” (1974) by Edward P. McAniff includes a chapter devoted to the Indirect “Fog” Attack.   You’ll also find advice on the use of water fog for cooling thermal columns, for ventilation, for preventing panic, and more.
3D Fire Fighting: Training, Techniques, and Tactics” (2005) by Paul Grimwood, Ed Hartin, John McDonough, and Shan Raffel compares Indirect “Fog” Attack to Pulse/3-D Transitional Attack and other attack tactics.  A thorough discussion of compartment fire behavior, extinguishment, fire streams, and training encompasses not only the Pulse/3-D Attack offensive tactic, but the defensive Indirect “Fog” Attack too.  The enclosed CD includes dramatic footage of a backdraft explosion created inside a training container.  The blast knocks a life-size dummy off its rocker.  This is followed by a demonstration of an Indirect “Fog” Attack used to safely extinguish another smoldering fire inside the same container.

Considering the dangers posed by initial decay (smoldering) phase fires, perhaps the principles of the Indirect “Fog” Attack should be the first lesson a new firefighter receives at a live-fire training exercise.  Isn’t the absence of this skill a dangerous oversight?  Every firefighter should know why, when, and how to do it.  And frankly, it’s usually the easiest fire attack you’ll ever do.  Learn and practice the Indirect “Fog” Attack.

Editor’ Note:

The fire company where I first learned to extinguish fires forty years ago had been using the Indirect “Fog” Attack since just after World War II.  A number of the men were navy veterans, and they had become familiar with fog firefighting while in the service.  Then, in 1946, a committee of company members attended a fog firefighting seminar in the village of Intercourse in the Amish farmland area of Lancaster County, Pennsylvania.  They were impressed by the demonstration.

The company purchased its first high-pressure “fog truck” in 1947.  A replacement followed in 1958.  A “fog truck” would be the first-out apparatus for every incident for the next 32 years.  Each of these vehicles was equipped with two reels of 1-inch hose, a pair of 600 P.S.I. fog guns, a high-pressure pump (800 P.S.I.), a booster tank of water, ground ladders, floodlights, and other firefighting accouterments.

And so it was at company drill that my peers and I were taught to extinguish a fire using a 30 G.P.M. water spray from a high-pressure fog gun.  It was the first tactic we learned, and it was exciting.  We opened the door to a burning room in the practice house, then whipped and swirled a thirty-to-forty-degrees-wide cone of water fog into the opening.  After closing the door, we’d wait impatiently for the O.K. to go inside (a minute or two is a long time when you’re young).  Then we would open a window and hydraulically ventilate the ballast from the place using a wider cone of water fog as a fan.  It was all over in five minutes.  Thirty seconds of water into the gaseous layer, fifteen gallons total, and the fire was out.

Now, please note that the rooms were burning when we extinguished them, not smoldering.  You see, the company tried to use an Indirect “Fog” Attack on nearly every fire.  And beyond that, they tried to use high-pressure fog on nearly every incident! 

Incipient visible fire?  High-pressure fog.  

Brush fire?  High-pressure fog.  

Petrol spill on the pavement?  High-pressure fog. 

Flammable liquids fire?  High-pressure fog.

Automobile fire?  High-pressure fog.

Pennsylvania Railroad boxcar full of burning U.S. Mail?  Gotcha…they used a 2 ½” hoseline from a 750 G.P.M. pumper on that one!

(Image by C. Bailey)

  Clogged drain?  You guessed it…high-pressure fog. 

And for most of these things high-pressure fog worked well.

Then there were the structural fires. 

For structural fires that weren’t well-ventilated and weren’t too big, the high-pressure fog was indeed effective.  But when the company pulled up on any kind of sizable structural fire, they would be almost helpless.  The “fog trucks” had no larger hoselines to deploy and no supply hose to lay.  It was a matter of mathematics.  The two 30 G.P.M. guns could use water fog to cool and try to contain the fire until help arrived, but any Direct Attack on the main body of fire was limited to extinguishment of 60 G.P.M. worth of fire (about 180 square feet).  When these larger fires occurred, the “fog truck” crew typically used up their tank water, then moved on to help advance larger lines from later-arriving units.

Nevertheless, the first fire I extinguished was in a scorched “finished basement” that had burned and was smoldering for maybe an hour or longer.  After slightly opening a door on the above ground side (it was a daylight basement), my partner and I put fifteen gallons of water fog into the hot ballast filling the “rec room”.  We closed the door, and a few minutes later it was time to enter, hydraulically ventilate, soak a sofa that flared up, and help the people save what they could in the remainder of the house.  It worked.  And I recall using it a number of times afterward, mostly on room and contents fires, most still in the free-burning growth phase.  (I recall too, messing around with short bursts of fog from the fog gun, not fully realizing the significance of it until later.  The trigger lock would engage and make bursts hard to control on the darned things anyway.) 

The Indirect “Fog” Attack using high-pressure water fog quickly extinguished many fires in my hometown.  It’s rapid effectiveness and the liberal deployment of salvage covers helped keep water damage to a minimum, and that helped gain the company a good reputation.  It was a favorite, especially before self-contained breathing apparatus (S.C.B.A.s) provided a safer way to enter a smoky building to put water on a fire. 

The company began purchasing S.C.B.A.s in the early 1960s.  By the mid-1970s, there were at least a couple on each pumping apparatus including the high-pressure “fog truck”.  Gradually, a shift to the Combination Attack was taking place as the members were able to penetrate into the fire building and use a Direct Attack to extinguish the seat of the fire.  Because of their greater flow capabilities, hand-held 1 ½” and 1 ¾” hoselines with 100 P.S.I. nozzles gained favor over the use of the smaller hose on reels.  As high-pressure fog lost popularity, the Indirect “Fog” Attack was gradually being forgotten or improperly applied.  It soon became confused with other tactics and was widely assumed to be a method that exposed crews to hot gases and steam as they applied water from a position inside the building (sounds like the Combination Attack to me).

The 1958 John Bean “fog truck” was removed from service due to mechanical failure in 1979 and a “Class A” pumper with an auxiliary high-pressure fog system was sold in 1991.  That was the end of high-pressure fog firefighting in my hometown.   

A 1947 Dodge/John Bean high-pressure “fog truck”.  John Bean originally manufactured crop and tree sprayers for use in agriculture.  The leap onto fire trucks occurred in the 1930s after a fruit grower allegedly used his John Bean orchard sprayer to fog and extinguish his neighbor’s house fire.

Can the Indirect “Fog” Attack still be effective on today’s fireground?  Absolutely, but only as a tactic in a defensive strategy carried out by personnel who understand the principles and methods of its use.

Could high-pressure fog be as effective for offensive Pulse/3-D firefighting as it was for the Indirect “Fog” Attack?  Yes, it could be, but higher flow rates would be desirable. 

Could a modernized high-pressure fog firefighting system be installed on today’s fire apparatus?  Certainly.  But remember, a fire pumper designed to extinguish building fires cannot be a “one-trick pony”.



Structural Fire Defensive Fire Attack Tactics

—Exterior Fire Attack (Surround & Drown, etc.)

Exterior Fire Attack

Regardless of the size of a fire, deficient resources, safety concerns, and other limiting factors sometimes compel an incident commander to use a defensive fire attack strategy.  When the fire has progressed to the “fully involved” or “coming down” stage, the decision is made for him/her —a defensive strategy is necessary.  Structural fires in the fully developed and vented (final) decay phases are contained using a defensive fire attack strategy as well.  During a defensive operation, the concern shifts away from the salvation of the building(s) of origin to containment of the fire and evacuation of affected structures.  However, if savable occupants still remain in the building(s) of origin, hoselines may need to be positioned to protect their removal.  This may include advancing hand-held hoselines into the fire structure(s) for just a period of time long enough to get everyone out and assure the safe retirement of firefighting crews.  Ultimately though, as the main body of fire engulfs a majority of the burning building(s), the property is written off as lost and the focus moves toward controlling extension, the potential evacuation of exposed buildings, and the establishment of a collapse zone.

Defensive fire attack strategy often utilizes the Exterior Fire Attack.  Everyone is familiar with the basic premise.  It is known by many descriptive and possibly more appropriate colloquial names including: the “surround and drown”, the “surround and drown and watch it burn down”, and the “surround and drown until the fuel burns up”.  Water is used to soak exposed surfaces to prevent ignition and, if practicable, to cool and possibly extinguish the main body of fire.  The difference between this defensive attack and an offensive one is the lack of an advance to the main body of fire.  The absence of close-in maneuvering makes this attack less efficient at water use than the offensive attacks.  In addition, a defensive strategy and Exterior Fire Attack may have been initiated because the fire’s flow requirements exceeded the supply immediately available.  As the fire engulfs more combustibles and threatens other structures, these requirements grow exponentially.  For these reasons, the largest and most sustained water supplies possible need to be developed for an Exterior Fire Attack.  Eventually, water application rates will be great enough to cool and extinguish a large fire—possibly because the cooling effect of the rate of application has exceeded the heat release rate of a fire in the growth or fully developed phase, but usually because the fire is in the decay phase and the heat release rate has diminished to within the cooling capacity of the fire streams being applied.  During an Exterior Fire Attack, fire stream management is critical.  Exposure buildings should not go unprotected and sacrificed so that fire streams can be applied into a main body of fire that cannot be cooled effectively.

Extinguishing a Fully Developed Fire
Frequently, the fire flow at the scene is inadequate for extinguishing a fully developed fire.  Under such circumstances, the available water supply must be used judiciously to contain the fire by protecting exposures and controlling extension until, during the decay phase, the fire’s heat release rate diminishes to a level within the cooling capacity of fire streams.

The Conflagration

Historically, the primary goal of firefighting was to prevent an inferno from burning building after building and creating a catastrophic conflagration.  Containment of a conflagration is a daunting endeavor.  Taking action to prevent or contain a conflagration requires a chief to carefully evaluate the strategic factors influencing formation of his/her operational plan.  Among the most pressing factors are…

        • Evacuation profile of exposed buildings.
          • Most endangered occupants.
          • Largest number of occupants.
          • Others in affected areas.
        • Size and intensity of the main body of fire (heat release rate).
        • Direction, speed, and intensity of fire spread.
        • Proximity and orientation of exposures to sources of radiant heat.
        • Collapse potential of the fire building(s) and exposures.
        • Construction and occupancy of the fire building(s) and exposures.
        • Fire protection features of the fire building(s) and exposures.
        • Available personnel and equipment.
        • Available water supply.
        • Wind and other weather conditions.
        • Significant special hazards.

To determine how best to deploy companies, utilize available resources, and achieve the most favorable outcome possible, these and possibly other strategic factors must be prioritized, then overcome or accepted as part of the operational plan that is implemented to protect lives and contain the fire.

The 1906 San Francisco earthquake fatally injured the city’s fire chief and ruptured gas lines resulting in numerous uncontrolled fires throughout the city.  Other fires were intentionally set by the owners of damaged properties to assure the receipt of insurance payments.  In an attempt to contain the merging infernos, firemen tried to create a firebreak, using dynamite to topple buildings ahead of the advancing flames.  This ill-conceived tactic ignited still more fires.  The conflagration, which burned for four days, was the most destructive component of the earthquake event, burning 25,000 buildings.  (National Archives image)  

A fire of great enormity, a conflagration, can be a once-in-a-lifetime experience for a firefighter.  Nevertheless, every fire department must have at its disposal the expertise and equipment to get ahead of and contain a large fire.  One of the most important strategic concepts described by McAniff , “Don’t chase fire; get ahead of it,” is sound advice for sure.  Emanuel Fried in Fireground Tactics (1972) provides a concise list of actions for containing and fighting large structural fires.  It’s a very general guideline, but it’s worth your consideration…


    1. The initial line placement heads off the fire spread.
    2. Then, the sprinkler system should be supplied. (fire building and exposures)
    3. Place additional lines so as to surround the entire fire area.
    4. Back up those hose lines in heavily involved areas or where men may be in danger.
    5. Fill in the supply to elevating platforms, ladder pipes, standpipe and sprinkler connections.
    6. Assign a spark and brand patrol if needed.
Firefighters surround and contain a church fire using master streams and hand-held hoselines, including at least one of the latter seen here being operated from the roof of a potential exposure building.  It’s the days before S.C.B.A.s and collapse zones.  (Image by Joan Clark Netherwood, circa 1975, Smithsonian American Art Museum, www.si.edu)

The following are a few points to consider regarding the adaptability of the large-caliber streams in your arsenal for defensive fire attack strategy and the Exterior Fire Attack…

A pre-connected portable master stream device.
A pre-connected portable master stream device equipped with a combination nozzle can be positioned quickly by a single firefighter to provide effective exposure protection using water spray.  A versatile appliance, it can also be used to contain a fire using a straight stream.  As an unmanned monitor nozzle, such devices can be put in place and used to cool storage tanks or protect other endangered property in hazardous locations.  Using the appropriate fixed-pressure (automatic) combination nozzle, a portable master stream set can be relied upon to continue producing a fire stream at flows as low as 100 to 200 G.P.M., an advantage of significance when fighting a large fire with a rural water supply or overtaxed municipal hydrant system.  The configuration seen here will flow up to 500 G.P.M.
A portable multiversal set operating with a smooth bore nozzle.
To help contain a large fire, a portable multiversal or deluge set can be positioned where it will achieve greatest effect.  Typical locations include, but are not limited to, alleyways, rear yards, side yards, and rooftops.  Provision of two 3-inch supply lines and use of a 2″ tip allows this unit to flow its maximum, just over 1,000 G.P.M. (42 MW of cooling at 25% efficiency).
A fixed-pressure (automatic) nozzle for master stream devices.
Having fixed-pressure (automatic) combination nozzles available for your master streams provides some protection against the reduced supply availability that may occur during a large fire being fought using rural water sources or diminished hydrant systems.  Below a critical minimum flow for its particular diameter, a smooth bore nozzle fails to produce a fire stream and lobs water to the ground.  The “automatic” combination nozzle seen here has a fixed pressure of 100 P.S.I., will flow up to 1,250 G.P.M., and will still produce a stream at a flow as low as 150 G.P.M.  It would make a suitable substitute for a stack tip set on a deck gun (deck pipe), ladder pipe, or portable master stream.  It just might keep you in business during those big fires when determining available fire flow is a matter of guesswork.
Elevating platform master stream devices equipped with combination and smooth bore nozzles.
A 100 P.S.I. fixed-pressure combination nozzle (left) is as necessary as a smooth bore nozzle (right) on a ladder or elevating platform.  While it’s ideal to have both ready for action, if you are able to be equipped with only one, you may want to consider the advantages of a versatile combination nozzle.  Its flow and reach can rival that of the smooth bore nozzle.  Unlike the smooth bore nozzle, it requires no time-consuming tip changes to significantly modify its flow.  The water spray from the combination nozzle is perfect for flowing water onto exposures to cool heated surfaces and prevent ignition.  Also, it can create an effective water fog for cooling the smoke and fuel in a thermal column emanating from a large fire (similar to indirect cooling of the ballast in a compartment fire).  Finally, the fixed-pressure combination nozzle has the previously described low flow advantages when used in place of a smooth bore during big fires with compromised water supplies.  Something to think about.
Firefighters reduce the radiant heat threat from a large fire by cooling its thermal column using water fog.
Thermal columns produced by ominously large infernos can radiate heat downward to ignite the roofs and upper floors of buildings downwind of the original fire.  This phenomenon has contributed to some catastrophic conflagrations.  To reduce the threat, a water fog is flowed from an elevating platform into the superheated column.  As the fog is vaporized to steam, it absorbs an enormous amount of heat energy from the smoke and fuel in the cloud, thus reducing the radiant energy output of the thermal column and often eliminating the ignition of gases that mix with air along its periphery.

Many defensive fires require interior firefighting operations in addition to the Exterior Fire Attack.  At a minimum, hoselines may need to be advanced into exposed buildings to control egress routes for evacuating occupants and to extinguish extending fire.  Lines advanced into exposure buildings can be directed at the main body of fire from windows and roofs after evacuations and extension checks are complete.  These are well-known and frequently used methods of controlling fires using a defensive strategy.

In addition to the implementation of an Exterior Fire Attack as a defensive measure to protect exposures from ignition and possibly cool the main body of fire, numerous offensive actions may be necessary in multiple nearby buildings that have caught fire after exposure to radiant or convective heat.  These building fires can sometimes be somewhat remote from the central fire and are often treated individually with companies assigned to fight them almost as a separate incident.  These huge blazes with their “satellite fires” can require enormous water supplies and scores of companies to contain.  Often, the use of water needs to be prioritized—strategy may be dictated by its availability.  Doctrine requiring that all firefighting be done from the exterior of buildings during defensive operations would be catastrophic when facing fires such as this.

When practicable, fires that have extended to interior areas of exposure buildings need to be extinguished promptly using offensive tactics.  Meanwhile in the area of the main body of fire (i.e., the building of origin), entry should be denied, and collapse zones established.  No one should be entering buildings deemed lost or within zones of potential collapse.  An incident commander needs to decide where the line will be drawn between that which can be saved, and that which will be lost.  That which cannot be saved needs to be “written off” as resources are concentrated on the salvageable.  Rational analysis of the scene is critical—risk lives only to save lives, maybe risk property to save property, and risk nothing to save nothing.

An Example of Defensive Ventilation—The Trench Cut

A roof ventilation tactic known as a trench cut is sometimes used to create a firebreak ahead of lateral fire extension in the common cockloft or attic space of burning interconnected rowhouses.  This defensive measure utilizes an opening about two feet in width to physically separate the roof surface between unburned homes and those “written off” as lost to the fire.

Prior to cutting the roof deck in preparation for opening a trench, a large vertical ventilation hole must be providing an exhaust point above the main body of fire to assure that smoke, fire, and superheated combustible gases aren’t drawn toward openings made by the saws.  If the intensity of the fire hasn’t already made such a hole, firefighters should cut and clear one before cutting a trench, provided, of course, that it can be done safely.  In the absence of a sizeable vertical opening, significant cooling of the main body of fire in the rowhome(s) of origin may be a prerequisite for any successful effort to contain lateral extension within a common cockloft or attic.*

* Consider the advantages of the Indirect “Fog” Fire Attack as a defensive option to extinguish fire extending through an unventilated cockloft or attic, particularly when the main body of fire in the rowhome(s) of origin can first be darkened with large-caliber fire streams.

When initiating the process of cutting a trench, kerf cuts and small triangular examination cuts should be made to observe conditions in the affected space between the main body of fire and the trench.  In addition, interior crews can make small observation openings to check conditions in the space between the ceiling and the roof deck.  These small holes, both above and below the fire, can be used for the insertion of nozzles for cooling and extinguishment, in some cases negating the need to open the trench (navy fog applicators and Bresnan cellar distributors can be ideal for this purpose).  After the series of cuts comprising the trench are complete, the roof is opened only if the fire engulfing the space between the roof decking and the ceiling is indeed progressing laterally in the direction of the cut, and only when interior hoselines are charged and in position on the unburned side of it.  After the trench is cleared of all covering and ceiling material, the roof is evacuated and monitored from the safety of an aerial ladder or elevating platform.  In the spaces below, companies operating the hoselines prevent extension into the unburned areas.  Meanwhile, heat and smoke emanating from the heavy fire in the “written-off” portion of the cockloft or attic escapes vertically through the trench.

Firefighters open a trench cut to contain a fire spreading through a loft shared by a series of rowhomes.
Crews prepare to open a trench cut ahead of a fire extending laterally through a common cockloft above a series of interconnected rowhomes.  Small observation openings including a kerf cut (the width of a single pass of the saw blade) and triangular examination cuts allow assessment of the fire’s progress.  Prior to opening the trench, the latter can be used as water application points for cooling and extinguishing fire in the space between the roofing material and ceiling.  Flow of water from the exterior must be coordinated with companies operating hoselines on the interior and, after the cut is opened and cleared, becomes impracticable on the “written off” side of the trench.

Trench cuts are effective not only when fighting fires in rowhomes, but to stop horizontal fire extension in other elongated structures and in the “throat” sections between interconnected buildings.  A trench cut can be used to isolate a fire threatening to extend to or from a wing or addition on a building.  A trench cut can be opened on the unburned side of a firewall to assure that heat and smoke aren’t penetrating and causing a fire extension concern in previously unaffected areas.  In some circumstances, a trench cut can supplement the vertical ventilation provided by an undersized opening above the main body of fire.  Because the process of cutting a trench and placing hoselines can be time consuming, it is always essential to work well ahead of the fire.  Most importantly, trench cut operations must include an ongoing assessment of the fire, the wind, and the building, including the roof.  If there is nothing to gain or conditions become questionable, get everyone off the roof and back out.

A trench cut for controlling fire extension through a loft or attic space.
An example of a trench cut used to stop lateral fire extension through the “throat” section separating two portions of a large building.  To reduce the time needed to cut, open, and clear the trench, a noncombustible bulkhead structure is incorporated as part of this firebreak.

On the fireground, it is always important to think ahead and get contingencies into place.  While a trench cut is being prepared, aerial ladders and/or elevating platforms should be supplied with water and readied for operation should the fire jump the firebreak and force companies staffing hand-held hoselines on the unburned side to vacate the exposure building(s).

A ladder pipe and portable master streams in operation.
Knowing how to maximize water supplies provides a fire department with the advantage of improved fire streams for an Exterior Fire Attack.  Here more than 1,600 G.P.M. is being flowed to supply three master streams from one hydrant 800 feet away.  Of course, this flow could be consolidated into just two streams to improve the reach and cooling capacity of each.


Water Supply


Does your fire department analyze the pressurized water supplies in its district?  Do you know the fire flow available from your water system and each individual hydrant?  Do you know the volume of water available from the system?  Do you conduct planning and drilling exercises to maximize your water supplies?

You need to know whether your water supply can or cannot support your fire attack strategy and the tactics you’ll employ to carry it out.  Simply put—if the rate at which you can apply water is too low and/or the volume of water available for application is insufficient, you are then limited to exterior tactics and very possibly a defensive fire attack strategy.  You’ve got to know where you stand.  And it’s not something you want to discover while a fire is burning.

The water supply(s) in your fire district should be evaluated periodically to find maintenance and design defects, and to determine volume and flow capacity.  Each hydrant should be regularly inspected and tested to verify its flow capabilities.  NFPA 291—Recommended Practice for Fire Flow Testing and Marking of Hydrants provides guidance on testing hydrants and documenting the process.  Color-coding can help firefighters know the flow rating of an individual hydrant.  Many water supply system operators paint the bonnets and caps on their hydrants according to the color-code scheme described in the NFPA 291 standard.


Available flow with a 20 P.S.I. residual pressure

Class AA blue-top fire hydrant.

CLASS AA     1,500 G.P.M or greater     LIGHT BLUE

Class A green-top fire hydrant.

CLASS A     1,000 to 1,499 G.P.M.     GREEN

Class B orange-top fire hydrant.

CLASS B     500-999 G.P.M.     ORANGE

Class C red-top fire hydrant.

CLASS C     less than 500 G.P.M.     RED

Chrome or yellow barrels usually indicate a municipal hydrant, while red barrels denote that a private system is supplying the water.  Rarely, purple barrels are used to warn of a non-potable water supply.

Fire hydrant on non-potable water supply.
The Occupational Safety and Health Administration (O.S.H.A.) recommends purple barrels to warn of a non-potable water supply, one not safe for human consumption or domestic use.  This system operator opted to paint the bonnet and caps purple.
Gravity tank on municipal water distribution system.
While it’s important to know the flow capabilities of your local pressurized hydrant system(s), it’s just as important to know the volume of water (quantity in gallons) available.  Your local water works operator can provide you with figures for: the capacity of gravity tanks, daily production volumes (wells, etc.), capacity available from connections with neighboring systems, and volumes available from suction sources from which the water utility can pump an additional supply during a fire.  The sum of these quantities, minus the system’s maximum daily domestic consumption, is the volume of water available for firefighting.
Maximizing fire flow from a pressurized hydrant.
Fort Indiantown Gap (PA) Fire Department Assistant Chief Sam Clark instructs students on techniques used to fully capitalize on the large flow available from a “blue top” (1,500 G.P.M. or greater) fire hydrant.  Here, each of the three discharges on the plug are used to supply three separate pump intakes on a 2,000 G.P.M. pumper using 5-inch and 3-inch fire hose.  Friction loss calculations enable students to determine the proper engine (pump discharge) pressure to feed water from the engine on the hydrant to another engine through 800 feet of 5-inch supply hose.  To maximize flow for a relay from a blue top hydrant like this, an engine apparatus with a pump capacity exceeding the flow of the plug is necessary.  A rarely used alternative is to place two engines on the source hydrant.
Master streams in operation.
The “blue top” hydrant fed over 1,600 G.P.M. to the engine on the plug, which then relayed it 800 feet through 5-inch hose to the engine seen here supplying a ladder pipe (600 G.P.M.) and two portable master streams (500 G.P.M. each).  Having an engine pumping the supply hose to overcome friction loss and connecting 3-inch hose from the yard connections to its pump had a combined effect on fire flow.  The flow through 800 feet of hose connected directly to the steamer connection was limited to approximately 1,100 G.P.M.  The additional 500 G.P.M. gained by adding the 3-inch hook-up lines and pumping the 5-inch supply line allows a third master stream to be operated and represents just shy of a 50% increase in fire flow at the scene.  That’s a big deal when you’re trying to contain a big fire!
Fire hydrant locator map.
Plotting the location of hydrant and static water sources on maps, then color-coding them to indicate the available flow rates can be a great way for firefighters to learn the water supplies in their district.  Making written or digital lists and charts of these assets can have the same benefit.  It’s not so much the product, but the process of producing it that can make your members knowledgeable about their local water supplies.  Participants can become familiar with the strengths and weaknesses in their water system.  Understanding water supply shortfalls ahead of time allows a fire department the opportunity to make preparations before these deficiencies become limiting factors that alter fire attack strategy and tactics.  So, get out there and survey.  You’ll be a better firefighter, driver-operator, fire officer, and fire department for it.


Water Supply

—Backup/Redundancy When Using Hydrants

To maximize flow and as a fail-safe, does your fire department assign an engine to “pick up” and relay pump the supply hose laid from a hydrant by an earlier-arriving company?  Does your fire department provide a secondary water supply as a fail-safe when interior firefighting is underway (separate hydrant, supply hose, pumper, etc.)?

Supply hose connected to fire hydrant outlets.
Having an engine pick up your supply line and pump it from the hydrant assures maximum fire flow and provides a measure of redundancy.  Should the pumping apparatus at the scene experience a mechanical failure, the engine on the plug, as an emergency measure, can attempt to provide sufficient pressure to push water through the supply line and disabled pump, then through hoselines to keep fire streams operating until the situation can be mitigated.
A forward lay of a single supply line.
Utilizing a pressurized hydrant system by connecting and charging supply hose with a diameter of 3 inches or greater establishes a potentially uninterrupted flow of water to the fire scene.  A forward lay is the most common hose stretch used today.  Split lays and reverse lays can also be effective methods of establishing reliable flows to a fire scene.
A forward lay of two supply lines.
A forward lay of two supply lines provides a fail-safe against a ruptured hose or a faulty coupling.  In this era of large diameter hose (L.D.H.), the use of a dual 3-inch hose lay has become a less-than-common event.  Reliance on a single L.D.H. supply line comes with some risk.  Three-inch is still a very versatile hose size.  It can often be used to supply adequate flow for fires in small, detached buildings, and it’s great for all those hook-ups!  Three-inch can cover your back when used as a supplemental supply hose.  Laying a 3-inch line alongside a large diameter hose can provide redundancy and improve flow capabilities on large incidents.  (For those of you carrying three-and-a-half…same deal.)
An engine on the hydrant pumping the supply line.
An engine connected to the hydrant and pumping the supply line maximizes fire flow and provides a fail-safe against a mechanical failure of the engine at the fire building.  Some departments use four-way hydrant valves which allow the first-in engine to hook up, open the hydrant, and charge their line autonomously.  The valve continues flow without interruption as a later-arriving engine company completes hook-ups and subsequently pumps the line to maximize flow.  In other departments, it is protocol for the second-arriving engine to “pick up” the first-in engine’s line at the plug, complete hook-ups, open the hydrant, and pump the supply hose.
An engine pumping from a secondary water source assures a backup supply.
Backup hand-held hoselines at the scene should be supplied from a source separate from that supplying the leadoff lines.  A supply from a second water source, in this case a hydrant on a separate “loop” within the grid system of underground water lines (blue and orange lines), provides a supply independent of the initial configuration established by the first-in engine.  Selecting hydrants each separated by an intersection of three or four converging underground distribution lines provides better assurance that the test flow of each plug can be fully realized.  A minimum of two separate water supplies assures that backup lines are truly available and that there is continuous flow at the fire building.
Automobile blocking fire hydrant.
That primary water supply may not be as reliable, or as accessible, as you first thought.  It’s essential that each responding pumper apparatus take a staging position at a potential water source so that the secondary and tertiary supplies can become established and flowing as soon as possible.  You never know when the first-in engine company is going to encounter a water supply or mechanical problem that impedes their ability to begin or continue operating.
A water supply setup that maximizes flow and provides redundancy.
An example of a water supply layout with assurance of redundancy in a district with hydrants.  Engines at two different plugs, each on separate “loops” within the grid network of underground water lines, are pumping dual supply lines to engines operating at the fire building.  Consider dual supply lines anytime an engine company needs to take a position in a location with limited access, such as in a narrow driveway, in an alley, back a country lane, or in a cul-de-sac.
4-way "Humat" Hydrant Valve Preconnected to Large Diameter Hose
Using the coupling closest to the camera to connect this 4-way “Humat” hydrant valve to a fire plug’s steamer outlet allows this engine company to complete a forward lay to the fire and charge the supply hose autonomously.  Use of the valve enables a later-arriving relay engine to take a position at the hydrant, complete hook-ups, open the diversion valve, and begin pumping to increase the water pressure and flow to the fire without ever interrupting the continuous supply.  Note that in this initial configuration, the water from the hydrant makes two 90-degree turns inside the valve before being discharged into the supply hose.  Due to these turns, friction loss in the device increases as flow rate increases.
4-way "Humat" Hydrant Valve
The 4-way “Humat” hydrant valve was originally developed for use with supply hose of smaller diameters (2 1/2″, 3″, and 3 1/2″) to allow a single engine company to autonomously initiate a water supply to a fire scene and still permit a later-arriving relay engine to pump the plug and boost the pressure and flow without interruption.
4-way "Humat" Hydrant Valve Supplying Engine at Fire Scene
An engine company can initiate flow to a fire scene through a 4-way hydrant valve using a single supply hose, usually pre-connected to the valve.  Dual lines can be stretched, but only one is connected to the valve; the other will need to be picked up and pumped by the later-arriving relay engine.  (Note that the diversion valve seen here is in the open position.  In actual use during the initial phase of the operation, it would need to be in the closed position to direct water from the hydrant to the fire through the pre-connected supply hose.)
Operation of a 4-way "Humat" Hydrant Valve
A later-arriving relay engine company increases pressure and flow in the original supply hose by making two hook-ups: one from the connection nearest the camera to the pump intake, and the second from a pump discharge to the threaded connection on the lower left of the device.  The diversion valve can then be opened enough to flood the pump and relay pumping can begin.  When pressure in the line from the pump discharge to the device reaches a value greater than that of the hydrant, a clapper flap will swing up to allow water to pass straight through the bottom section of the device to the fire, and, as the diversion valve is fully opened, straight through the top section of the device from the hydrant to the intake on the pump.  Friction loss caused by bends and turns within the device are minimized when it is in this relay pumping configuration.  If dual supply lines have been dropped, the second may be connected to a suitable discharge on the relay engine and pumped as needed.
Four-way hydrant valve pre-connected to large-diameter supply hose.
Because water passes from the pressurized fire hydrant straight through this device and directly into the pre-connected supply hose without any bends or turns, this 4-way hydrant valve specifically designed for use with large diameter hose has the advantage of minimal friction loss when operating without the assistance of a relay pumper on the plug.  (Note that the hydrant connection is facing down and is hidden from view by the mounting hardware.)
Four-way hydrant valve.
Overhead view of a 4-way hydrant valve showing labels for the hydrant and hose connections, as well as the diversion valve (left) and clapper flap (right) positions.
Connections for using a four-way hydrant valve.
To take full advantage of the flow capacity of a good hydrant, a valve (a ball valve works well) should be attached to each yard connection on the plug before it is opened.  A later-arriving engine company can begin pumping the supply line(s) after hooking up to the intake and discharge connections on the 4-way hydrant valve.  Then, if necessary, flow can be maximized by hooking up additional hoselines (usually 3-inch) from the valves on the hydrant’s yard connections to the intakes on the pump.  Using this method, the flow to the fire scene can be progressively improved by the engine company pumping at the hydrant without fear of interrupting the water supply.  Furthermore, if two supply lines (say a 5-inch and a 3-inch) are being pumped from the engine at the hydrant to the engine at the fire, any burst hoseline or apparatus mechanical failure within this water supply configuration can be isolated, bypassed, or overcome using the hose and valves already in place. The flow of water need not be interrupted but for the brief time needed to close a valve or two.


Water Supply


Does your fire department serve locations without fire hydrants, i.e., rural areas?  Does your fire department analyze the static water supplies in its district?  Do you know the flow and volume capacity of each source?  When firefighting in rural areas, do you have adequate tank water arriving promptly on a first alarm to maintain the flow rate needed to utilize an offensive fire attack strategy?  Do you use first alarm tankers/tenders in nurse configuration when engaged in interior firefighting?  Can you provide a separate water source for backup hoselines while interior firefighting is in progress (a second tanker/tender and a pumper or a pumper-tanker/tender)?  Do you use “porta-tanks”, tanker/tender shuttles, relay pumping, and/or drafting to supply interior firefighting only after these rural water supplies have been well-established and a backup is at the ready?  Do you either use exterior tactics for your offensive fire attack strategy or adopt a defensive fire attack strategy when adequate water supply is not yet available or cannot be maintained?

For discussions including mobile water supply apparatus on this page, we use the terms tanker and tender together as “tanker/tender”, meaning a tanker or a tender.  Many jurisdictions specifically refer to a tender as a vehicle used exclusively to nurse feed a fire service vehicle with water, fuel, etc.  Here, “tanker/tender” refers to any fire service vehicle used primarily to transport water to a fire scene.  A tanker/tender lacks the manpower, quantities of hose, and fire suppression equipment typically found on engines, quints, etc.   A tanker/tender has a water capacity of at least 1,500 gallons and is often equipped with a large dump valve for use during water shuttle operations.  Using this term, we also include the “tanker-pumper”, a tanker/tender equipped with a pump (usually at least 1,000 G.P.M.) for off-loading water quickly during either nurse or shuttle operations.  Some tanker-pumpers are equipped with several hand-held hoselines pre-connected to the pump.  Such a tanker-pumper could, in the absence of a second-in engine apparatus at the scene, be used as a secondary water source to not only supply, but also pump additional hoselines for fire attack, exposure protection, support, or backup.

Large dump valve on a fire service tanker.
A tanker/tender equipped with a large dump valve.  This apparatus can quickly discharge its water into a portable tank from which it is drafted and pumped to the fire.  Time saved during off-loading and filling during water shuttle operations can increase the flow rate available at the fire scene.

The term “pumper-tanker/tender” refers to a fire service vehicle designed and equipped to function primarily as an engine company, but with a tank capacity of 1,500 gallons or greater.  Many departments refer to a pumper-tanker/tender vehicle as an “engine-tanker”.  During initial operations, a pumper-tanker/tender can be very effective as a free-standing first-in engine, as a nurse supply for a first-in engine (with a full-size pump for redundancy), or as a purveyor of backup hoselines with an autonomous water supply.  They are capable of drafting at a porta-tank or other static water source, and, in any configuration, can use their large tank capacity as a reserve in the event of a supply interruption.  Size, however, may sometimes render a pumper-tanker/tender less maneuverable for use as a water shuttle vehicle.

A special message of caution regarding tankers/tenders:

Vehicle accidents are the second most common cause of firefighter line-of-duty deaths.  (Behind stress-induced aggravations of preexisting conditions such as heart disease, high blood pressure, etc.)  The most accident-prone fire service vehicle is a tanker/tender, accounting for 20-25% of fatal crashes, despite comprising only about 3% of the nationwide fleet.  (Firefighters driving their personal vehicles during a fire department function account for about 40% of fatal crashes.)  These incidents injure and kill civilians as well as firefighters.  Despite improvements in design, tankers/tenders are susceptible to rollover, especially while cornering at excessive speed, while in a skid, or when wheels get into a soft shoulder on the edge of the roadway.  These vehicles are far safer to operate at slower speeds—they should probably be holding up traffic instead of pushing it.

The incident commander, while reconnoitering the fire scene and performing size-up, is wise to promptly evaluate the resource requirements for the event.  If assistance might be needed from additional companies (i.e., extra alarms), the request for their dispatch should be made forthwith.  More often though, the number of companies that are responding or dispatched exceed the necessities at the scene, so the surplus can often be sent home.  Regarding the companies continuing to the scene—are they all urgently needed?  Should they be responding at “emergency rate”?   An incident commander can improve safety for firefighters and civilians by taking action.   Don’t delay, especially if tankers/tenders are responding— “TURN EM’ AROUND OR SLOW EM’ DOWN”.  Then too, consider the status of tankers/tenders making their way through a circuitous load and dump route during a water shuttle operation—do they really need to be traveling at an emergency rate?  If you really need to increase the rate of water flow at the fire scene, why not plug more tankers/tenders, fill sites, and dump sites into the circuit instead of having units drive fast?

For more information, you can read these reports from the United States Fire Administration: Safe Operation of Fire Tankers (2002) and Emergency Vehicle Safety Initiative (2014).

You get the idea.  Now back to rural water supply…

A tanker/tender using a nurse configuration supplies water to a fire engine.
Driver-operators learn rural water supply.  Here a 3,000-gallon tanker/tender is used to nurse feed an engine through a 3-inch hookup line.

A nurse tanker/tender configuration can be used to provide water for most of the tactics used when employing an offensive fire attack strategy.  To initiate a “Fast Water” Structural Transitional Attack or Blitz Attack, water from the first-in engine’s booster tank can be used to cool and “reset” the fire from an exterior position.  When indirect cooling from the exterior is not necessary, booster tank water can be used to begin the interior attack, provided that continuity can be assured by a prompt hookup to a nurse tanker/tender if needed.  An engine carrying greater than 500 gallons of water (750 or 1,000 for example) can provide the extra margin needed to achieve extinguishment with booster tank water using an offensive attack against a fire involving one or two rooms and the contents therein.  For greater safety though, interior firefighting, including the advance on the seat of the fire for a Direct Attack, should be supported using water supplied from the tanker/tender to the engine.  Using the water from a 3,000-gallon tanker/tender, a 1 ¾-inch hand-held hoseline equipped with a combination nozzle flowing 134 G.P.M. can be supplied for about 20 minutes of continuous use—two lines for ten minutes.  A smooth bore nozzle flowing 175 G.P.M. could be maintained for at least 15 minutes of uninterrupted use.  To provide some degree of redundancy, a backup line can advanced from from the nursing tanker/tender and pressurized using its onboard pump.  Better yet, backup lines can be supplied by a secondary water source such as a separate tanker/tender and engine configuration or pumper-tanker/tender.  If the attack on the fire is progressing as desired, additional nurse tanker/tenders can assure uninterrupted water flow to complete extinguishment and overhaul.

Important: Don’t let crews inside the building run out of water during the fire attack.  Most offensive attacks should result in a knockdown of a bulk of the fire within five or six minutes.  Get a progress report.  If a break in the continuity of the water supply is possible, and crews have expended half of the capacity of a tanker/tender without locating and knocking down the fire, consider backing them out immediately.  You need to assure that the water they have remaining is sufficient to cover their retirement from the building.


A Nurse Tanker/Tender Configuration
A tanker/tender in a nurse configuration uses a 3-inch hookup line (A) to feed water to a first-in engine as it pumps one or more attack hoselines (B).  As a safety measure,  a backup hoseline (C) can be stretched from the tanker/tender and supplied by its onboard pump.
Nurse Tanker/Tender Pumping Through a First-in Engine Experiencing Mechanical Failure
In the event of a mechanical failure involving the first-in engine, a nursing tanker/tender can use its pump to maintain pressure and flow in the the initial attack line(s) by pushing water through the disabled pump.  Because the tanker/tender may need to pump at a discharge pressure exceeding 200 p.s.i. to properly supply the nozzle(s) on the attack line(s), large diameter hose with a 200 p.s.i. service test pressure should not be used as a hookup line.

An Engine and Tanker/Tender in Nurse Configuration Duration of Flow with Engine and Tanker/Tender in Nurse Configuration


Providing a Secondary Water Source with a Nurse Configuration
To provide a secondary water source for multiple fire attack and backup hoselines, two separate nurse tanker/tender configurations are established.  Redundancy is assured by connecting supply lines (marked with blue arrows to show the direction of flow) between a discharge and an intake on each of the engines, allowing either to pump to the other during an emergency.  If necessary, this initial setup can receive a supplemental supply by methods including additional nurse tankers/tenders, a water shuttle operation, and/or relay pumping.

A Primary and Secondary Water Source Provided by Engines and Tankers/Tenders in Nurse Configuration Duration of Flow with Primary and Secondary Water Sources Comprised of Engines and Tankers/Tenders in Nurse Configuration

For incidents requiring lengthy operations or a defensive strategy, particularly those involving larger buildings and bigger fires, nurse tankers/tenders are essential for buying time and maintaining continuous flow while sustained water supplies from drafting, relay pumping, and/or a water shuttle are established.  Remember, monitoring your water supply is critical and you must fight the fire from an exterior position or use a defensive strategy with exterior tactics if the continuity of the supply is not assured.  Whether you plan to use an offensive or a defensive strategy, it’s often best to use the tankers/tenders on your first alarm in this nurse-feed configuration.   It is certainly prudent to drop large-diameter supply hose and porta-tanks early in the operation but think carefully before using first alarm tank water to fill them, especially if firefighters are in interior firefighting positions or exposures need protection.

A tanker/tender in nurse configuration supplies water to a fire engine pumping to a portable master stream device.
A master stream flowing 400 G.P.M. will deplete a 3,000-gallon tanker/tender in approximately seven minutes.  If flowing 800 G.P.M., the tank water will be gone in just over three minutes.

In rural districts, water supply can become an overwhelming limiting factor and it alone may dictate fire attack strategy.  Fire strategy, therefore, must be selected carefully and water arriving on the first alarm must be used judiciously.  Your evaluation of the situation may indicate that the arriving water supply is sufficient and an attack on the main body of fire will succeed, so an offensive strategy is implemented.  Conversely, the water supply may be insufficient, or slow to materialize, so you may have no other choice than to commit to a holding action, a defensive-offensive strategy, until a water supply capable of tackling the main body of fire can be developed.  Often, the lack of a continuous and sufficient water supply, or sometimes the stage of the fire, prohibits firefighters from committing to anything more than the control of fire extension—a defense strategy.  It goes without saying that in rural districts, good fire stream management is necessary regardless of the strategy selected.  Use your first alarm water wisely.

Large-diameter hose connected to a manifold used for rural firefighting.
An engine company tasked with rural water supply may be equipped to perform a reverse lay of considerable distance to a water source from which it can relay pump.  The portable hydrant (manifold) seen here can be dropped at the scene as a distribution point, then supplied using large diameter hose (in this example: 6-inch).  Note the floating strainer (on the shelf) for use when drafting from a static source that may contain debris near the bottom.  Once established, such a water supply configuration may continue operating uninterrupted for many hours.  However, the time between arrival and completion of the setup could be lengthy, so prudent use of tanker/tender water and careful fire stream management are necessities in the interim.
The IFSTA “Pumping and Aerial Apparatus Driver/Operator Handbook” Third Edition (2015) is also available without the aerial apparatus chapters as the “Pumping Apparatus Driver/Operator Handbook”.  Both contain a wealth of information for utilizing rural water supplies and include chapters on static water supply sources, relay pumping, and water shuttle operations.  Formulas are found therein for determining the capacity of unique static water sources such as indoor and outdoor swimming pools.

When evaluating water supplies to determine their capabilities for fire protection, the Insurance Services Office (I.S.O.) may recognize suction points on static or flowing water sources as the equivalent to hydrants—as long as they are accessible on each and every day of the year.  To qualify, the fire department must be able to establish a minimum flow of 250 G.P.M. within 5 minutes of the arrival of the first-in engine company, and it must maintain that flow without interruption for a minimum of two hours.  The I.S.O.’s website, www.isomitigation.com, especially the pages describing “Alternative Water Supplies” and the “Fire Suppression Rating Schedule”, can provide more information on using suction points and other rural water supplies to improve your tactical capabilities and I.S.O. Public Protection Classification rating.

N.F.P.A. 1142
N.F.P.A. 1142 can help a fire department fill the gaps in its water supply capabilities.  Every driver/operator and fire officer should own a copy of N.F.P.A. 1142 and be familiar with its contents.  For reference and perusal by the members during “down time”, your firehouse should have a copy available in a conspicuous location.  Therein one will find guidance on the effective use of alternative water supplies.  Included are sample water usage agreements, detailed instructions for calculating water-carrying potential, and guidelines for improving and sustaining fire flow.  Design standards for installing “dry hydrants” assure year-round access to ponds and other static water sources.  Set-up and use of jet-assist devices and other equipment is discussed in a section on porta-tank setup and layout.  Suggestions for the use of portable pumps are offered to allow the utilization of otherwise inaccessible water supplies.  Looking to purchase and/or equip a new mobile water supply apparatus?  You’ll want to consult this standard.  There is even a section on designing vehicle turnarounds for use during tanker/tender shuttle operations.

Dry Hydrants

A “dry hydrant” provides year-round access to a suction point on a static water source for drafting.  Dry hydrants are most often installed at bodies of water in rural areas where they may be the only supply source for miles around.  Sometimes, dry hydrants are used as backup and supplemental sources in areas primarily served by municipal hydrants.  Many states will fund the installation of dry hydrants in rural districts through their agency responsible for forest fire planning, prevention, and suppression.  As long as housing continues to be located within forests and wild land areas without adequate provisions for fire protection, the installation of dry hydrants will remain vital to assuring at least a minimal all-season water supply for fighting fires.

A dry hydrant installed to use water from a lake for rural firefighting.
This dry hydrant provides an additional water supply for a forested resort community within which the municipal hydrant system provides an inadequate volume and rate of flow for the fire hazards located there.  Relay pumping from the dry hydrant to a fire scene could easily supply an additional 1,000 G.P.M. or more for suppression efforts.  Then too, the dry hydrant could serve as a source for a fill site during a water shuttle operation, thus providing water to a fire scene located miles away.  In winter, the flooded portion of the suction pipe in this installation remains well below the ice on the lake and the frost zone in the ground.
A dry hydrant installed to use water from a stream for rural firefighting.
A dry hydrant can be located at a suction point on a moving stream with a reliable base flow.
Intake strainer installed on a dry hydrant system used to supply water for rural firefighting.
The intake for a dry hydrant using a stream as a water source needs to be located in a pool with sufficient depth to allow the strainer to be positioned above any debris and silt that may accumulate on the bottom.  Compared to slow-moving creeks, fast-moving well-oxygenated streams similar to the one seen here are less likely to freeze to any great thickness in winter.  The flat top on this strainer is a foot below the water’s surface, its depth suitable to access fluid water below a sheet of ice and its shape designed to prevent an intake of air into a fire pump due to a whirlpool effect.  The rate at which water flows into and maintains the depth of a drafting pool determines the flow capabilities of the stream for drafting operations.  A minimum flow of not less than 1,000 G.P.M. is desirable for any waterway that is being considered for installation of a dry hydrant or designation as a drafting site.

Estimating the Capacity of a Flowing Water Source

(Stream, Creek, River, etc.)

More to follow on this topic soon.

Estimating the Capacity of a Still Water Source

(Swimming Pool, Fiberglass Tank, Pond, Cistern, etc.)

Still sources including ponds, lakes, swimming pools, cisterns, and fiberglass tanks can be suitable alternate water supplies in rural districts.  N.F.P.A. 1142 provides guidelines for their use and a formula for estimating their capacity.  During the pre-fire planning process, you’ll want to secure permission from the owner to access the water source during a fire or for training/drilling purposes.  It’s also very important to evaluate safety concerns at the site.  Will the the sides of the pool collapse if the water is removed, particularly if a motorized pumping apparatus is parked alongside?  Are there hidden hazards that may be difficult to discern, especially during hours of darkness?  Is the source safely accessible on a year-round basis?  Is water present on a year-round basis?

A Swimming Pool

Estimating Capacity of a Swimming Pool


Water Supply

—Estimating Total Water Supply

Does your fire department calculate the minimum Total Water Supply and Delivery Rate necessary for containing and extinguishing fires involving the various structures within your rural districts—including areas where the existing hydrant system falls short of the flow and/or volume requirements for the buildings found there?

N.F.P.A. 1142
N.F.P.A. 1142 provides guidelines and a formula for calculating the minimum Total Water Supply and Delivery Rate for containing and extinguishing fires in rural areas and other districts lacking adequate water resources.

Knowing the water supply needs of a building can help a fire chief avoid fundamental mistakes when making strategic and tactical firefighting decisions.  A chief may subject firefighters to injury or death by committing forces to an offensive attack before an adequate flow and/or volume of water is available for completing a knockdown of a fire in a given structure.  Conversely, a chief with a fully adequate supply at the ready could squander the opportunity for a fast knockdown and incident mitigation by errantly delaying the quick commencement of an offensive attack—instead assigning companies to water supply tasks that are either unnecessary or could be performed by later-arriving units.  Remember, fast-growing modern fires present a much smaller window of opportunity for use of an offensive strategy, so whenever resources are sufficient, seize the moment and act promptly.

Determination of a building’s flow and volume requirements as part of the plans review or pre-fire planning process can provide an opportunity for securing the necessary infrastructure, fire equipment, response assignments, and other contingencies for preventing a deficient water supply from becoming an insurmountable strategic factor during a fire.  The worst time for a fire chief to speak up and say we don’t have enough water to put out a fire is while he or she is standing in front of a television camera with a smoldering heap in the background—a heap that used to be someone’s home or business.

N.F.P.A. 1142—Standard on Water Supplies for Suburban and Rural Firefighting provides guidance for estimating the Total Water Supply (T.W.S.) needed for structural firefighting in areas where pressurized hydrants are absent or are inadequate to provide the volume and flow necessary for containment and extinguishment of a building fire.  All current and aspiring fire officers should be familiar with this standard and should spend time calculating the water supply needs of various structures found in his/her district.  The process of performing the calculations can be a real eye opener, helping one to better understand the extremes in water supply needs.  As a bonus, these calculations make a great addition to pre-fire plans.  There are operational benefits as well.  To minimize or eliminate water supply as a strategic (limiting) factor during a fire, a department that is truly committed to protecting lives and property must work hard beforehand to identify flow and volume deficiencies so that solutions can be planned and implemented well in advance of an incident.

Formula for Estimating Minimum Total Water Supply

A survey of the building under evaluation should note its enclosed dimensions (length, width, and height in feet), occupancy type, construction type, and distance from exposures.  This basic data is then used to populate the following formula to calculate the minimum Total Water Supply in gallons needed for manual firefighting:


The volume of the structure in cubic feet is determined by multiplying its length, width, and height in feet.

The product is divided by the…


      • Severe Hazard—Use a divisor of 3 for feed/flour/grain mills, flammable liquid spraying, plastics manufacturing, die casting, sawmills, etc.*
      • High Hazard—Use a divisor of 4 for mercantiles, repair garages, warehouses, commercial barns and stables, theaters, department stores, etc.*
      • Moderate Hazard—Use a divisor of 5 for farm buildings, machine shops, restaurants, cold storage warehouses, libraries, unoccupied buildings, etc.*
      • Low Hazard—Use a divisor of 6 for bakeries, churches, municipal/post offices, dairy plants, gas stations, horse stables, etc.*
      • Light Hazard—Use a divisor of 7 for dwellings, apartments, hotels/motels, hospitals, offices, schools, fire/police stations, etc.*

*See your copy of N.F.P.A. 1142 for a complete listing.

The quotient is then multiplied by the…


      • Type I (Fire-resistive) Construction requires a C.C.N. of 0.5
      • Type II (Noncombustible) Construction requires a C.C.N. of 0.75
      • Type III (Ordinary) Construction requires a C.C.N. of 1.0
      • Type IV (Heavy Timber) Construction requires a C.C.N. of 0.75
      • Type V (Wood Frame) Construction requires a C.C.N. of 1.5

Note: The maximum C.C.N. for all dwellings is 1.0.

The product is the estimated Total Water Supply in gallons.

The minimum Total Water Supply for any structure without exposures is not less than 2,000 gallons.

Minimum Total Water Supply for Buildings with Exposures

A structure poses an exposure hazard if it is located within 50 feet of an evaluated building and has an area of at least 100 square feet or has an O.H.C.N. of 3 or 4, regardless of floor space.  If an exposure hazard is present, the minimum Total Water Supply for the building being evaluated is increased by 50%, therefore the calculated minimum Total Water Supply must be multiplied by 1.5…

The minimum Total Water Supply for any structure with exposures is not less than 3,000 gallons.

Reduction for Approved Automatic Fire Sprinklers

N.F.P.A. 1142 allows the authority having jurisdiction to reduce the Total Water Supply by as much as 75% for buildings equipped with an approved automatic fire sprinkler system fully meeting either N.F.P.A 13—Standard for the Installation of Sprinkler Systems, N.F.P.A. 13D—Standard for the Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes, or N.F.P.A. 13R—Standard for the Installation of Sprinkler Systems in Low-Rise residential Occupancies.   Structures protected by systems not meeting the applicable sprinkler standard are subject to the full Total Water Supply requirements of N.F.P.A. 1142.

Delivery Rate

Based upon the Total Water Supply (T.W.S.) calculation for a given building, N.F.P.A. 1142 requires that the water be conveyed to the scene of a fire at a minimum rate known as the Delivery Rate, expressed in gallons per minute (G.P.M.).

      • T.W.S. <15,000 gallons—250 G.P.M.
      • T.W.S. 15,001-22,500 gallons—500 G.P.M.
      • T.W.S. 22,501-30,000 gallons—750 G.P.M.
      • T.W.S. >30,000 gallons—1,000 G.P.M.

The Delivery Rate should not be confused with flow estimates such as “Needed Fire Flow” and “Rate of Flow”, which are calculated specifically as water application rates for extinguishing a fire using the Direct Attack in the case of the former (determined using the National Fire Academy formula) and the Indirect “Fog” Fire Attack in the case of the latter.  Nor should it be confused with the “Needed Fire Flow” as determined by the Insurance Services Office (I.S.O.), which is a rate for containing and extinguishing a fire involving 100% of a building and its contents while using a pressurized municipal hydrant system.  The Delivery Rate is rather a rate at which water must be transported to a fire scene to provide some assurance that a continuous supply is available for fire streams to be at least minimally effective for containing a large fire and possibly extinguishing a smaller one.  Think of it as a flow rate intended to be an absolute minimum for sustaining a defensive Exterior Fire Attack while using rural water supplies.  To meet or exceed the Delivery Rate requirements, any number of conveyances may be used including mobile water supply apparatus, hoselines, or a combination of both.  Where water from pressurized hydrants is absent or inadequate, supplies can be obtained from alternative sources approved by the authority having jurisdiction.  These may include static sources such as ponds, lakes, streams, rivers, cisterns, etc.  Supplies from approved alternate sources can be delivered to the scene using a water shuttle and/or relay pumping.

The minimum Delivery Rate for any fire is not less than 250 G.P.M.  According to N.F.P.A, 1142, the authority having jurisdiction can “adjust the water delivery rate, giving consideration to local conditions and need”.

Examples: Total Water Supply for Selected Buildings

Note: For structures up to 1,000,000 cubic feet in volume, Annex H of N.F.P.A. 1142 provides precalculated minimum Total Water Supplies for each Occupancy Hazard Classification Number.

An Outbuilding (480 square feet)

Requires at least one tanker/tender load (3,000 gallons or more) to meet its minimum Total Water Supply needs.

For many buildings, particularly dwellings, it is appropriate to measure height as 10 feet per story—just to make your calculations easier.  To add the volume of space in the attic to your Total Water Supply calculation, add half the height from the attic floor to the ridge pole to the height multiplier in the equation.  In this example, we add 5 feet of height to arrive at a total building height of 15 feet.

This outbuilding is being used an environmental classroom, therefore it has an Occupancy Hazard Classification number of 7.  Despite the calculation calling for a T.W.S. of 1,543 gallons, the minimum Total Water Supply for any structure is 2,000 gallons—3,000 gallons if their is an exposure hazard within 50 feet.  Because the neighboring elementary school is being sold, this structure is scheduled to be vacated.  The change in occupancy will lower the Occupancy Hazard Classification Number to 5—the O.H.C.N. divisor for unoccupied buildings, farm storage buildings including equipment sheds, corn cribs, tobacco sheds, etc.—and will hence increase the Total Water Supply to 2,160 gallons.  If there is an exposure hazard measuring 100 square feet or more in area located within 50 feet of the vacant outbuilding, the T.W.S. is increased by 50% to 3,240 gallons.  The Delivery Rate will remain the same.

A Mobile Home (720 square feet)

Requires at least one tanker/tender load (3,000 gallons or more) to meet its minimum Total Water Supply needs.

Again, the minimum Total Water Supply for any structure is 2,000 gallons—3,000 gallons if there is an exposure hazard within 50 feet.

Note that the buildings in this and the previous example often require just one tanker/tender or pumper-tanker load of water to meet their minimum Total Water Supply requirements.  However, you’ll always want a second source present for supplying backup hoselines during an offensive fire attack and to provide redundancy for defensive fire streams.

A Manufactured Home (1,200 square feet)

with Exposure Hazard

Requires at least one tanker/tender load (3,000 gallons or more) to meet its minimum Total Water Supply needs.

Because the attic spaces on most manufactured units of this type are negligible, a 10 foot height measurement for a single-story home is adequate.  Located within 50 feet of the left side of the home is a garden shed larger than 100 square feet in area.  This structure poses an exposure hazard so we increase the minimum Total Water Supply by 50 %—multiplying by 1.5.

Its popularity not limited to the manufactured housing market, the 1,200 sq. ft. footprint is widespread among stick-built dwellings constructed during the post-World War II housing boom.  In many rural and suburban fire districts, the 1,200 sq. ft. outline was utilized in new construction through at least the end of the twentieth century, particularly in subdivision developments.  A majority of these homes feature a gabled roof with unfinished attic space beneath.  To determine minimum Total Water Supply for the following examples, we add the volume of space in the attic to our calculation by adding 5 feet (half the height from the attic floor to the ridge pole) to the height multiplier in the equation.  Because these homes are often placed within 50 feet of each other, we calculated the Total Water Supplies with a 50% increase for the exposure hazard—multiplying our preliminary result by 1.5.

Traditionally Constructed (Stick-built) Single-family Dwellings

with a 1,200 sq. ft. Footprint

Total Water Supplies calculated for examples with exposure hazards.  Delivery Rate is 250 G.P.M. for all examples.
A 3,600-sq.-ft. dwelling on a 1,200-sq.-ft. footprint requires at least three tanker/tender loads averaging 3,000 gallons or more to meet its minimum Total Water Supply needs.

Because they require significantly greater water supplies, firefighters and fire officers should learn to recognize buildings with sizes exceeding the 3,600 sq. ft. benchmark.  Take note that with 3,600 sq. ft. of living space plus an attic, the wood-frame dwelling with a 1,200 sq. ft. footprint requires a Total Water Supply equal to three loads of water from tankers/tenders or pumper-tankers with a capacity averaging 3,000 gallons.  The current twenty-first-century trend towards larger home sizes has increased Total Water Supply needs beyond the capabilities of three mobile water supply vehicles to response requirements comparable to those needed for some commercial occupancies.

Furthermore, when determining minimum fire flows using both the International Fire Code and Insurance Services Office (I.S.O.) methods, fires involving one-family and two-family dwellings with up to 3,600 sq. ft. of floor space can have significantly reduced requirements.  All other buildings require minimum fire flows of at least 1,500 G.P.M.  More on that to come.

A Small Restaurant (3,600 square feet)

This 3,600-sq.-ft. restaurant requires at least four tanker/tender loads averaging 3,000 gallons or more to meet its minimum Total Water Supply needs.

Due to the open floor plan found throughout most of a restaurant or other similar commercial occupancy of this size, the Needed Fire Flow for a Direct Attack on the seat of the fire as estimated using the National Fire Academy (N.F.A.) formula is 300 G.P.M. for just 25% involvement, a figure already exceeding the Delivery Rate for transporting the calculated 10,800-gallon Total Water Supply to the scene.  This divergence increases exponentially with building size and highlights the fact that Delivery Rate is not intended to be a water application rate.  The reader will find further discussion of this example in the “Selecting Hoselines for Fire Attack” section found later on this page.


A Twenty-first-Century Single-family Dwelling (5,700 square feet)

A 48 x 40 x 35 McMansion

This “McMansion” requires at least four tanker/tender loads averaging 3,000 gallons or more to meet its minimum Total Water Supply needs.

This stick-built dwelling has a finished and unfinished floor area totaling 5,760 square feet plus attic space—a figure comparable to many buildings containing multi-family residences.  In rural and suburban fire districts, single-family homes requiring water supplies rivaling those needed for commercial properties are becoming increasingly prevalent for new construction, particularly where land is expensive.  As if things aren’t bad enough, the dwelling in this example, if placed within 50 feet of another house to save space, would require a Total Water Supply of 14,400 gallons—a 50 % increase for the exposure hazard.  Despite their greater flow and volume requirements, these homes are often erected in locations lacking pressurized fire hydrant systems or nearby approved alternative water supplies.  Even though the necessary minimum Total Water Supply could be reduced by as much as 75% with installation of residential fire sprinklers, these systems are seldom included where not mandated by state or local law.

Because of the larger dimensions and open floor plans in these homes, fire flow requirements for a Direct Attack are also increased.  Using the National Fire Academy (N.F.A.) formula, the Needed Fire Flow for 50% involvement of just one floor in this house is 320 G.P.M.  Rapid fire growth in these dwellings, sometimes further complicated by the lack of a nearby fire station, has frequently eliminated an offensive fire attack as an option.  Fires in these homes often exceed the flow capabilities of first-in firefighters or have already fully engulfed the structure upon arrival.  A fire chief has little option but to contain the flames and protect exposures.  Yet, despite their obvious necessity, no residential fire sprinklers are installed.  For those buying these expensive homes in the woods, the rule of the Forrest—”Stupid is as stupid does”—certainly applies, don’t you think?

A 54′ x 32′ Bank Barn

with Exposure Hazard

54 x 32 x 30 Bank Barn

This 54′ x 32′ bank barn requires at least eight tanker/tender loads averaging 3,000 gallons or more to meet its minimum Total Water Supply needs.

Total Water Supplies for bank barns in use to store farm equipment or house livestock including dairy cattle are calculated with an Occupancy Hazard Classification Number of 5.  Other uses may require a different O.H.C.N.

This barn has an exposure hazard, a silo and a tobacco shed located within 50 feet of the rear of the structure, therefore we increase the Total Water Supply by 50%—multiplying our preliminary result by 1.5.

A 54′ x 32′ Bank Barn Storing Hay

with Exposure Hazard

54 x 32 x 30 Bank Barn

This 54′ x 32′ bank barn if storing hay would require at least thirteen tanker/tender loads averaging 3,000 gallons or more to meet its minimum Total Water Supply needs.

Bank barns used for hay storage require a greater Total Water Supply, so an Occupancy Hazard Classification Number of 3 is used as a divisor in the calculation.  In this example, the increase in Total Water Supply has bumped the Delivery Rate up a notch to 1,000 G.P.M.—the maximum for any building or site where N.F.P.A. 1142 is applicable.

This may be a good place to remind the reader that the N.F.P.A. 1142 formula provides an estimate of the minimum Total Water Supply necessary for manual firefighting.  Fire stream management plays a big role in the quantity of water that will actually be used on the fireground.  Continuous operation of a marginally effective ladder pipe or other master stream could quickly increase the volume of water needed to bring an incident to a close.  Marathon operations to fully extinguish burning and smoldering stockpiles of hay, paper, and other stubborn contents can have the same effect.  Instead of needing 13 tanker/tender loads of water to mitigate a fire involving this barn, a fire chief may need twice as many or more.

Cluster of Farm Buildings
To function as a static water source for fire protection, this farm has a large pond situated alongside the entrance driveway.  When evaluating properties with multiple buildings sharing one water source, the structure with the greatest supply requirement determines the minimum Total Water Supply for the site.


Because water should not be used to extinguish fires inside oxygen-limiting (sealed) silos due to the risk of explosion, and because N.F.P.A. 1142 does not specifically address the Total Water Supply requirements for conventional silos, the following links should be consulted.  They provide guidance on the  specialized resources such as the carbon dioxide or nitrogen gas that may be needed to mitigate incidents involving these structures.

A Conventional Silo
Beyond the quantity of water needed for application to the exterior for protection as an exposure hazard, N.F.PA. 1142 does not specifically address water supply requirements for farm silos.

Commercial Pork or Poultry Barn (8,325 square feet)

with Exposure Hazard

185 x 45 x 15 Poultry Barn

This 8,325-sq.-ft. poultry barn requires at least twenty-four tanker/tender loads averaging 3,000 gallons or more to meet its minimum Total Water Supply needs.

Total Water Supplies for commercial barns and stables are calculated using an Occupancy Hazard Classification Number of 4.  Because the Total Water Supply is greater than 30,000 gallons, the Delivery Rate is 1,000 G.P.M.  To transport the required 70,242 gallons to the fire scene at this rate, a shuttle operation using tankers/tenders with an average capacity of 3,000 gallons will require 24 loads—one every three minutes for a duration of just over one hour.


A Warehouse/Freight Terminal (1,000,000 square feet)

This 1,000,000-sq.-ft. warehouse requires at least nine hundred thirty-eight tanker/tender loads averaging 3,000 gallons or more to meet its minimum Total Water Supply needs.

N.F.P.A. 1142 makes provisions for the authority having jurisdiction to increase water supply requirements “to compensate for particular conditions”.  The majority of rural departments responding to fires in oversize warehouses face two of the conditions on the N.F.P.A. 1142 list—”limited fire department resources” and “extended fire department response time or distance”.  The building itself may present a third, particularly if high rack storage is in use—”special uses and unusual occupancies”.

Let us consider the Delivery Rate for the Total Water Supply required by the warehouse in our example.  Even without an increase in the Total Water Supply to “compensate for particular conditions”, at a rate of 1,000 G.P.M. it will take nearly two days (46.875 hours to be exact) to deliver the required 2,812,500 gallons of water to the fire scene.  Put in perspective, if you used a shuttle operation with tanker/tenders averaging a capacity of 3,000 gallons, it would require 938 loads—one every 3 minutes.  For a building this large, the effectiveness of water delivered at such a trickle comes into question.  Will it even be enough to contain a fire, never mind extinguish it?

The precalculated Total Water Supply charts in Annex H of N.F.P.A. 1142 include T.W.S. figures for buildings with volumes up to and including 1,000,000 cubic feet—nowhere close to the 60,000,000 cubic feet of some modern-day warehouses and fulfillment centers.  One might question the applicability of N.F.P.A. 1142’s Delivery Rate figure which remains constant at 1,000 G.P.M. regardless of whether the building is 1,000,000 cubic feet in volume requiring a Total Water Supply of 62,500 gallons or 60,000,000 cubic feet in volume requiring 2,812,500 gallons.  At the 1,000 G.P.M. Delivery Rate, the required 62,500-gallon supply for a fire in a warehouse measuring 1,000,000 cubic feet will arrive in just over one hour, fast enough for the water to have satisfactory effect if judiciously applied.  One might remember that there is a caveat to the determination of N.F.P.A. 1142’s Delivery Rate—the standard does allow the authority having jurisdiction to adjust it based upon “local conditions and need”.  But how much of an increase is adequate?  A Delivery rate of 10,000 G.P.M. gets the Total Water Supply there in a more realistic time frame of just over four hours, but how could water ever be transported to a fire scene in a rural or suburban setting at that rate?  The majority of rural departments are hard pressed to maintain a flow of 1,000 G.P.M. for three or four hours.  Suburban fire departments blessed with a good municipal hydrant system may be capable of developing a fire flow of 3,000-4,000 G.P.M. for 4 hours, but others aren’t so fortunate.  Herein lies the problem.  When it come to delivering millions of gallons of water at an effective Delivery Rate, rural and suburban fire departments just don’t have the resources to do it.

Another concern that arises with oversize warehouses is the reliability of automatic fire sprinklers.  There have been fires where automatic sprinkler systems have failed to provide extinguishment when high-rack storage was in use.  Should a fire gain a significant foothold and exceed the capabilities of the sprinkler system, manual firefighting becomes the only recourse for either putting out the fire or presiding over the complete demise the structure.  But getting water onto the fire presents a real challenge.  Rural fire departments in particular are seldom prepared for the extensive hose stretches that may be necessary to reach burning combustibles inside massive buildings.  Delays resulting from such logistical difficulties may present a fire chief with no other choice than to resort to a defensive strategy out of concern for the integrity of web-truss roofing and other structural members.  Big fires in some of these monster buildings have developed into marathon events lasting—you guessed it—two days.  The buildings and contents become a total loss.

But the impact does not end there.  During these prolonged operations, firefighters and local residents can be subjected to an extended period of exposure to the byproducts of combustion contained in the vast clouds of smoke produced.

How about another dilemma?  Flow millions of gallons of water at a fire involving one of these buildings and a significant amount of contaminated runoff will certainly be generated.  How do you contain it before putting personnel, civilians, groundwater, and streams at risk?  Not an easy task.

It seems self-evident that a rural or suburban setting with limited water supplies and fire department resources is a less-than-ideal place to test the impact these big buildings will have on fire protection performance and planning—not to mention public health and safety.  Placement of these immense structures within rural and suburban districts dooms a fire chief to the insurmountable strategic factors of a critically insufficient water supply and the probability of an extended deficient resource stage, leaving him/her with no alternative but to cautiously preside over the total destruction of the building and its contents.

Sometimes it’s just foolish to roll with the tide.  A rural or suburban fire chief confronted with construction of a “mega-warehouse” building measuring hundreds of thousands of square feet or more in area needs to put pride aside and make it known that there is no way the fire department can assure containment and timely extinguishment of a fire in a structure with such oversize dimensions.  You need to draw the line.  For the good of your department and community, just say no!


Water Supply

—Planning Response Assignments

Does your department use “local alarm” and/or “tactical alarm” response assignments as “economy of force” measures?  If you use tactical assignments, are the responding companies capable of delivering a water supply sufficient for use of an offensive fire attack strategy for a fire in a single-family or two-family dwelling with a floor area of up to 3,600 square feet?  Can the companies that respond on your full first alarm assignments deliver the water supply necessary for employment of an offensive fire attack strategy to fight a fire in a non-residential building or a single-family or two-family dwelling with a floor area exceeding 3,600 square feet?  Using the companies that will arrive on a first alarm assignment, are you able to employ an offensive-defensive strategy for a fire in a multiple dwelling or row home?  If not, will the second alarm companies be adequate to fill this need?  Do your tactical and first alarm assignments provide companies sufficient for development of the water supplies and fire streams needed to begin containing a large fire using a defensive strategy?  Do you know the Needed Fire Flow and Basic Fire Flow requirements for your jurisdiction as calculated by the Insurance Services Office (I.S.O.)?  Do your greater alarms provide the resources necessary to maximize your available water supplies and improve your defensive capabilities?  Using these resources, can a sufficient fire flow be delivered to the scene of a large fire involving one or more of your largest buildings?  In rural districts, do your response assignments provide the companies necessary to achieve the Delivery Rate required for transporting the minimum Total Water Supply to the fire scene?

Firefighters are generally familiar with the concept of response assignments or “box alarms”.  The latter term is a carryover from the early days of firefighting in cities and large towns where telegraph alarm boxes located on street corners were used by residents to summon the nearest fire company(s).  Inside an activated box, a rotating gear with a series of teeth spaced at intervals unique to that particular device closed and opened an electrical circuit to send a three-digit or four-digit numerical signal to a fire station or central alarm room.  The transmitted number indicated to those monitoring the system the location of the activated box, and the closest companies would be summoned to respond.  Today, the term “box alarms” is generally used as a synonym for response assignments dispatched by 911 centers based upon the location, occupancy, and type of incident reported.  This modern alerting is accomplished with the assistance of a database that has been loaded into a computer-aided dispatch (C.A.D.) system.  Entry of an address generates a listing of the closest available companies in descending order of proximity to its “phantom box area” (a geographic area without an actual alarm box, but for which a unique series of response assignments have been planned).  With entry of the type of incident—and possibly other variables such as time of day, season, weather, or day of week—a list of how many of each type of company, and the specific identities of those due to be dispatched, is generated by the C.A.D.

A Gamewell fire alarm box.  (Smithsonian image, www.si.edu)

Outside of urban and county-wide fire departments, the responsibility for predetermining response assignments for entry into a 911 center’s computer-aided dispatch system may be assumed by any of a variety of entities.  A county fire marshal’s office, emergency management office, or other agency may conduct the planning and establish assignments collectively for all of the departments within its jurisdiction.  In other regions, fire chiefs in each local department or company are accountable for response assignments and the mutual aid agreements needed to assure adequate resource availability.

Many fire departments use an identical initial response assignment for a given set of incidents that are anticipated to have similar needs to mitigate them.  Examples of specialized assignments include:

        • Still Alarm Assignment—A non-emergency response, typically consisting of just one company, often an engine or a ladder, for a non-fire task.  A company is traditionally summoned to a still alarm assignment by telephone.  (public service calls, fallen trees, flooded cellars, etc.)
        • E.M.S. Alarm Assignment (E.M.S. Box)An Emergency Medical Services response that includes companies whose primary role is traditionally fire suppression.  (cardiac arrests, lifting assistance, Advanced Life Support provider, first responder, etc.)
        • Rescue Alarm Assignment (Rescue Box)A response primarily for the purposes of non-fire rescue.  (injurious traffic accidents, extrications, water rescues, etc.)
        • Mass Casualty Alarm Assignment (Mass Casualty Box)A response for incidents involving the potential for injuries to, and the possible need for rescue of, large numbers of persons.  (accidents and/or fires involving buses, aircraft, trains, hospitals, nursing homes, schools, etc.)
        • High-rise Alarm Assignment (High-rise box)A response for fighting fires in high-rise buildings.  Additional resources on the assignment may include high-pressure engines, extra ladder and rescue squad companies, apparatus equipped with floor below nozzles (F.B.N.s) and wind control devices (W.C.D.), breathing air/mask service units, positive-pressure ventilation equipment, and supplemental communications and supervisory personnel.
        • Haz Mat Alarm Assignment (Haz Mat Box)A response for mitigating hazardous materials incidents.  (spills and leaks of fuels, chemicals, gases, hazardous waste, etc.)

Many departments have found success using these specialized assignments for their responses to incidents that fall outside the realm of everyday fire suppression.

A water rescue team drilling in cold weather.
Specialized assignments can include provisions for the response of resources with unique capabilities for mitigating not-so-everyday emergencies.

Familiar to nearly all firefighters, at least in part, is the series of three initial response assignments for fire suppression.  Their names, employment, and composition vary regionally, but most jurisdictions use some similar system for structuring fire company response.  For mitigating larger incidents, these assignments can be sequentially upgraded to summon responses from additional resources to provide more personnel, an improved water supply, specialized equipment, or a tactical reserve of companies.

        • Local Alarm Assignment (Local Box)A task-level fire response consisting of one or more companies, often from one station—frequently two engines, or an engine and a ladder (areas with hydrants), or an engine and a tanker/tender (rural areas).  A “Local Box” is dispatched for small incidents, many that may involve fire (outdoor fires, automobile fires, wires, odors, alarm activations, etc.).  Because it is often used to investigate automatic fire alarms, resources on the assignment should be sufficient to access a water supply with a minimum flow of 250 G.P.M. for initiating extinguishment or containment of an incipient phase building fire.  If a building fire is encountered, a local assignment is normally upgraded to either a tactical or first alarm assignment, depending upon conditions and/or department protocol.
        • Tactical Alarm Assignment (Tactical Box)A tactical-level fire response often consisting of, in areas with hydrants, two engines and one or two ladders, or, in rural areas, two engines, a ladder or rescue squad, and two tanker/tenders.  A “Tactical Box” provides adequate equipment and manpower for use of an offensive attack to extinguish a fire in a single-family or two-family dwelling with a floor space of up to 3,600 square feet.  As an alternative, the assignment can implement a defensive strategy to initiate efforts to contain a large fire and stop its extension.  Resources on the response should be capable of developing an initial water supply with a minimum flow of 250 G.P.M., then improving that flow to a minimum of 1,000 G.P.M. for offensive fire attacks.  In areas with fire hydrants, the tactical response should be capable of developing a minimum flow of 1,500 G.P.M. for fire containment using defensive measures.
        • First Alarm Assignment (Box Alarm, Fire Box, or just “Box”)A strategic-level fire response that provides adequate equipment and manpower for using an offensive attack to extinguish a fire or for implementing a defensive strategy to initiate efforts to contain a large fire and stop its extension.  Resources on the response should be capable of developing an initial water supply with a minimum flow of 250 G.P.M., then improving that flow to a minimum of 1,500 G.P.M., particularly in areas with fire hydrants.  With good staffing, a first alarm assignment will sometimes prove sufficient for both the offensive and defensive components of the offensive-defensive strategy used to fight fires in row homes, multiple dwellings, etc.
A sample of the sequential upgrading process for a fire response in a hydranted “box area” populated primarily by single-family and two-family dwellings.  In this example, a chief requesting an upgrade from a local alarm directly to a first alarm would receive the balance of the companies due: three more engines and one additional ladder.
Some jurisdictions, particularly those with an abundance of buildings larger than single-family and two-family dwellings, opt out of the use of tactical assignments and instead rely on the response of a lean first alarm assignment as an economy of force measure.  Many of them use an “all hands” or “working fire” upgrade to bolster the response for handling structural fires requiring extensive offensive attacks or offensive-defensive operations.  In the example shown here, a chief requesting an upgrade from a local alarm directly to an “all hands” or “working fire” assignment would receive the balance of the companies due: an additional three engine companies and two ladder companies.  Suppose a fire chief has transmitted a call for a second alarm to improve the fire flow at the scene of a defensive operation.  He/she would receive the four engine companies and three ladder companies collectively due on the local, first alarm, and “all hands” assignments, plus the companies due on the second alarm response.

Many factors need to be considered when determining the structure and composition of response assignments for fires.  The principles among these include: the travel distance and response time of companies, water supply needs and availability, manpower requirements and availability, and any advantages gained by summoning special equipment.  A company with a first-due district containing not only areas with adequate hydrants, but also rural areas without them, will have response assignments that differ significantly for each.

A company’s first-due district (A) is comprised of the addresses closer to its station than to other fire houses.  Because a response assignment in an area requiring use of rural water supplies differs significantly from one in an area with hydrants, a first-due district should be divided into separate zones for each (B).  These zones should then be divided, as needed, based on the proximity of second-due and, in extraordinary cases, third-due companies (C) to create geographic response areas, a.k.a. “box areas”.  Because they contain no actual telegraph alarm boxes mounted along the streets or on buildings, these areas have also been called “phantom box areas”.  For each “box area” (eight in this example), a list of each type of company can be created: one for engines, one for ladders, one for tanker/tenders, one for rescue squads, etc.  This list is often called a resource file.  A company’s position on a given resource file is based upon its distance from that particular file’s “box area”, closest at the top of the list, furthermost at the bottom.  A “box area’s” resource file is used by the computer-aided dispatch system to populate an alerting list with the closest available companies in the quantities prescribed by the response assignment for the type of incident reported.
Prior to dividing a hydranted or rural zone into “box areas” solely on the basis of travel distance, significant differences in resource requirements should be given serious consideration.  A building fire in a section of a hydranted zone comprised of institutional, industrial, commercial, or high-rise structures certainly necessitates the response of a greater number of companies than would be summoned for a fire in a neighborhood of duplexes and single-family homes.  Segments of zones, both hydranted and rural, where buildings or infrastructure present exceptional life hazard, fire flow, water supply, and other challenges should probably be afforded their own response assignments by being designated as “box areas” separate from those with lesser needs.
A "Run Book" with response assignments ("box alarms") and maps.
Geographic response areas can be numbered for identification purposes.  In this example, a residential area in a hydranted zone within Station 30’s first-due response district has been designated as “Box Area 300-1”.  On the map, numerical notations for neighboring “box areas”, both within Station 30’s first-due district and within the first-due district of Station 17 to the north can be seen.  The page to the right in this “run book” shows the response assignments for “Box Area 300-1”.

The most reliable way to assure a timely arrival of companies on the fireground is through the use of well-structured resource files that list the companies in descending order of proximity to each individual “box area”.  It should be mentioned, however, that in some cases, all or most of the companies located within a municipality or fire protection district are due on assignments before any mutual aid companies can be summoned to respond, regardless of the travel distance or turnout time involved—political necessities taking precedence over tactical sensibilities.

Fire response ("box") assignments for a geographic zone.
Station 30’s response plan for “Box Area 300-6” includes six alarms.  Shown below them is the resource file listing companies in descending order of proximity to “Box Area 300-6”.  The companies comprising each alarm, followed by the extra ones listed on the resource file, are moved up in sequential order to cover any companies that are unavailable for service or have failed to turn out after dispatch.  Note that the engine companies listed on this particular resource file are all extras, available to cover shortfalls on the first six alarms or be “special called” to form the equivalent of four more alarms if needed.  Does your dispatch center have resource files for each of your response areas that enumerate the closest engine companies, in order of proximity, in the quantities requisite for populating ten alarms?   In this example, that’s 33 engine companies!
Fire response ("box") assignments for a single special hazard building.
“Box Area 300-16” consists of a single property, an eight-story high-rise building among the much smaller structures of “Box Area 300-6”.  Compare the response assignments for the two.  For a fire located in the “box area” with the high-rise, note the increase in the number of companies, particularly ladders, summoned on the first three alarms.

A department’s foremost goal when structuring its response assignments is to eliminate strategic factors that could otherwise adversely influence the formation of the operational plan for fighting a fire.  The most common of these factors is usually water supply and manpower.  Addressing shortcomings in either or both of these critical resources should be a priority as response planning proceeds.

In the wake of Hurricane Katrina, New Orleans firefighters experienced pressure deficiencies when using hydrants to fight large fires.  Water supplied by a fire boat and a F.E.M.A.-funded helicopter supplemented flows established to fight this four-alarm warehouse fire on May 17, 2006.  Even in “box areas” with exceptional hydrant systems, resource files should include lists of companies and special equipment that may be needed to access and deliver alternatives to traditional water supplies.  Anticipate the unthinkable.  (National Archives image by Marvin Nauman, F.E.M.A.)

The first step is to gather information.  You may be able to begin your fact-finding effort by contacting the Insurance Services Office (I.S.O.).  The I.S.O. is a for-profit company that evaluates a municipality’s fire suppression capabilities and then sells that risk analysis information to insurance companies.  Community by community, insurers set the rates for residential and commercial fire insurance customers based on the I.S.O. rating schedule.  (Note: For determining premiums, many insurers are now abandoning the I.S.O. rating in favor of sneaky things like fire loss statistics and consumer credit rating algorithms.)

Your I.S.O. Public Protection Classification rating and, more importantly, the survey documentation used to determine that rating, including the Fire Suppression Rating Schedule, will provide valuable information on the flow requirements for buildings in your jurisdiction.  It will also include an evaluation of your municipal water supply and your department’s capabilities for delivering that supply to the scene and applying it to extinguish a fire.

Editor’s Note:

The I.S.O. uses the term “Needed Fire Flow”, for their estimate of the amount of water needed to fight a fire in a described building.  It is expressed as a rate in G.P.M. required for a specified length of time in hours.  The I.S.O. estimate is not contingent upon the type of attack used, the percentage of involvement, or other parameters.  It is very simply the rate and volume of water required to contain and extinguish a fire involving an entire building and its contents.  The I.S.O. formula is useful for municipal and fire department planning, but it is not intended for use on the fireground.

On the other hand, the National Fire Academy (N.F.A.) formula’s “Needed Fire Flow” estimate specifically determines the flow rate (not volume) necessary to extinguish a fire using a Direct Attack in a space with less than 50% involvement and needing less than a 1,000 G.P.M. flow.  It and other estimates for specific fire attacks using hand-held hoselines are discussed in “The Bottom Line—Get Water onto a Ventilated Fire Fast” section at the very end of this page.  They are applicable to fireground use. 

The reader will discover that the Insurance Services Office, International Fire Code, and N.F.P.A. 1142 estimates that are presented here as goals for minimum water supplies to be delivered to a fire scene by your response assignments are, by no coincidence, adequate for the attack requirements described later in “Selecting Hoselines for Fire Attack”.


The I.S.O. uses a complex formula to determine the “Needed Fire Flow” (N.F.F.) for individual buildings in a jurisdiction (I.S.O.’s Guide for Determination of Needed Fire Flow is available on the web).  The minimum N.F.F. for any building they survey is 500 G.P.M., the maximum can be as high as 12,000 G.P.M.  Significant allowances are made for buildings equipped with automatic fire sprinklers that meet specific requirements.  The fifth highest N.F.F. in a jurisdiction is known as that community’s “Basic Fire Flow”.

During the evaluation process, the I.S.O. compares the community’s “Basic Fire Flow” to the capabilities of the municipal water supply and the fire department’s ability to deliver that supply onto a fire.  Scores that contribute to the determination of a Public Protection Classification rating are largely influenced by hydrant flow, hydrant spacing, and the volume of water available in the distribution system for firefighting (40 of 105.5 points).  Proficiencies or deficiencies in a fire department’s response, staffing, training, apparatus, pump capacities, and special equipment affect the score by adding or subtracting points respectively (50 of 105.5 points).  Emergency communications (10 of 105.5 points) and community risk reductions (5.5 of 105.5 points) also contribute to the rating schedule’s score.  Shortcomings, particularly those related to water movement, can sometimes be addressed at minimal cost by implementing some careful logistics planning and subsequent adjustments to response assignments.

The minimum flow requirements of the International Fire Code are similar to those determined by the I.S.O. formula.  Many states and communities have adopted this code either as written or as amended.  Regardless of whether your community has adopted the International Fire Code or not, you may find the information in Appendix B: “Fire-flow Requirements for Buildings” and Appendix C: “Fire Hydrant Locations and Distribution” very useful for response planning.

Examples of the basic fire response assignments follow.  To help describe their fundamental structure, fire flow figures from the I.S.O. and the International Fire Code are used to set the minimum water supply that should be delivered to the fire scene for each assignment in an area equipped with fire hydrants.  In addition, N.F.P.A. 1142—Standard on Water Supplies for Suburban and Rural Firefighting is the source for some benchmark water supply minimums for responses in rural districts (those without adequate pressurized hydrant systems).

Defining a hydranted vs. a rural fire response zone.
In a “hydranted” response zone or district, fire plugs must be located less than 800 to 1,000 feet from every building.  The aggregate fire flow for the hydrants within this distance of each structure must be equal to or greater than the minimum necessary for containing or extinguishing a fire involving that building (always 1,500 G.P.M. or greater in non-sprinklered structures).  Where a hydrant system is absent or fails to meet these requirements, buildings must be included in a “rural” response zone or district.  Response assignments in rural districts should be structured to take advantage of tanker/tender water, static suction sources, and any hydrants that might be available to initiate or supplement flow and volume (such as the “orange top” plugs on the dead-end line seen here).  Greater alarms or task force responses can be created to provide the extra companies needed to set up water shuttle operations and/or relay pumping to deliver supplies from these sources to a rural fire scene.
A fire hydrant in a corn field used for flushing water lines.
Hydrants and suction points must be accessible year-round to be considered reliable for response assignment planning.  The hydrant seen here could be classified, at best, as a seasonal supplemental source in this rural district.  It was installed to flush a low point in the water main located beneath this corn field.  Nevertheless, if a fire chief had no better option, a large-diameter hoseline could be “hand-jacked” through the corn and bushes to access the plug and use it to bolster the supply needed to fight a fire.

Please note that these examples enumerate the companies necessary for the delivery and application of water using apparatus with sufficient crews (4 to 6 members per engine or ladder company).  They include mention of engines, ladders, and tanker/tenders only.  This is solely for the sake of brevity.  Your first alarm responses, and possibly your tactical assignments, will certainly include additional companies for safety and support, including at least one Rapid Intervention Team (R.I.T.)/ Firefighter Assistance and Safety Team (F.A.S.T.).  It may be that your fire district is equipped with exceptional water supplies, but, because staffing levels are not so great, you need to create responses that bring in additional apparatus on each assignment just for the manpower.  Some departments may also be responsible for adding any necessary E.M.S. assets to their response assignments.


Water Supply

—Response Assignments in Hydranted Districts


Local Alarm Assignment—Hydranted District

As a task-level response, a local alarm assignment in an area equipped with pressurized fire hydrants should have the capability of accessing and delivering to the scene a minimum flow of 250 G.P.M. to supply at least one hand-held hoseline for containing and extinguishing a fire.   No less than a “red top” hydrant (less than 500 G.P.M.) with a flow known to be greater than 250 G.P.M. should be used.

A class C red-top fire hydrant.
A “red top” plug with a test flow of 250-499 G.P.M. @ 20 P.S.I. (Class C) can provide the minimum water supply required for initiating a fire attack in a response area equipped with pressurized fire hydrants.  Be careful though, the red color-code is acceptable for all Class C hydrants, including those with test flows well below 250 G.P.M. @ 20 P.S.I.
A class C black-top fire hydrant.
To distinguish them from “red top” plugs capable of flowing 250-499 G.P.M., some jurisdictions mark Class C hydrants having a test flow of less than 250 G.P.M. @ 20 P.S.I. with a black bonnet and caps.  The black color-code is a warning to firefighters that this particular Class C hydrant will not provide the minimum fire flow for initiating a fire attack.

In communities with good hydrant spacing (not greater than 500 feet) a company will be capable of getting water to the front of a property by dropping less than 300 feet of supply hose.  One engine company with good staffing may be sufficient for handling most minor outdoor fires in these areas.  If your department is using a local alarm as an economy of force measure to respond to automatic fire alarms or investigations inside buildings, an additional company (engine or ladder) should be added to the assignment.  If an incipient phase fire is discovered, these companies will have the resources needed to initiate an offensive fire attack to extinguish it and begin a primary search of the premises.

An example of the deployment of a local alarm response in a hyranted area.
An example of the deployment of a local alarm assignment consisting of an engine and a ladder.  Having encountered a porch fire while investigating reports of a smell of smoke, the companies have secured a water supply with a flow exceeding 500 G.P.M. (well above the 250 G.P.M. minimum for initiating a fire attack) and advanced a hand-held hoseline to extinguish the fire.  If the fire has progressed beyond items on the porch to involve structural components of the building, the incident commander should upgrade the assignment immediately.

In areas with hydrant spacing exceeding 500 feet, or where hydrant pressures are known to be unreliable, a second pumping apparatus may be necessary on local alarm assignments.  An engine that can “pick up” the supply line at the hydrant and relay pump water to the engine at the scene will eliminate the latter’s intake pressure worries and assure that a continuous water supply has been established.  On hydrants with flows approaching 1,000 G.P.M. and greater, having an engine pumping at the plug will maximize flow delivery to the fire.

A local alarm assignment is like a “reconnaissance in force”, tasked, on the majority of incidents, with tackling the main body of fire offensively.  But the fire department needs to be ready for surprises.  A fire can easily be larger than it first appears.  The rapid growth of an incipient phase fire must always be anticipated and, if possible, countered.  If, upon arrival, companies do find a fire involving a building, an upgrade to a greater response assignment should be transmitted without delay.  Companies should begin establishing the water supply needed to implement the most appropriate fire attack strategy.  As usual, an offensive fire attack, if practicable, is the most desirable.  If a defensive strategy is required, companies should use the water at their disposal to protect victims in immediate peril and, secondarily, to cut off the fire’s spread.  Because of its tactical limitations, a local alarm assignment may be the most likely to engage in a “holding action” (a defensive-offensive strategy) to buy time until adequate help arrives to extinguish the main body of fire.

A portable pre-connected "step gun" for firefighting.
Buy Time on a Task-level or Tactical-level Response- These popular “step guns” can be pre-connected for easy deployment by one firefighter.  Among their many uses, they can be positioned defensively as an unmanned device for applying a water spray onto exposures.  When equipped with the 100-500 G.P.M. combination nozzle seen here, they require minimal flow and are ideal for implementing a “holding action” until staffing and/or water supplies are sufficient to begin an offensive attack against the main body of fire.

Tactical Alarm Assignment—Hydranted District

A tactical alarm assignment is sometimes used as an economy of force response to fires in single-family and two-family dwellings.  It is structured for tactical-level operations.  Most often, the response employs one of the offensive fire attacks—securing an adequate water supply, cooling and extinguishing the fire, and extending a primary and secondary search—all while making full use of its limited resources.  It may be the ideal response for handling compartment fires involving a room and contents.  Tactical assignments are commonly used in urban areas to keep as many companies as possible available for simultaneous fires and other calls for service.  By reducing the demand for resources, they can help minimize “call stacking” during busy periods in the dispatch center.

The tactical alarm assignment must be capable of delivering the minimum water supplies needed for the various attacks used to extinguish or contain fires occurring in one-family or two-family dwellings.  While the booster tank on the first-in engine may be sufficient for an Indirect “Fog” Attack, other tactics require significantly more water.  Supply hose must be laid from the municipal hydrant system to the scene.  The response of apparatus and personnel must be adequate for providing the hose, pumping the water, and applying the water onto the fire.

The International Fire Code recommends that a 1,000 G.P.M. flow be available from the pressurized hydrant system for one hour to fight fires in non-sprinklered one-family and two-family homes having a floor space of up to 3,600 square feet.  In a neighborhood with fully-sprinklered homes, this rate can be lowered to 500 G.P.M.

The Insurance Services Office (I.S.O.) Needed Fire Flow (N.F.F.) for one-family and two-family dwellings up to two stories in height is determined by the proximity of exposure buildings, but is never less than 500 G.P.M., even in areas where some or all of the homes are fully sprinklered.  The N.F.F. is 750 G.P.M. if exposures are within twenty-one to thirty feet of the fire building, 1,000 G.P.M. if within eleven to twenty feet, and 1,500 G.P.M. if within ten feet.

The Needed Fire Flow for the Direct Attack on the main body of fire as estimated by the National Fire Academy formula (see “The Bottom Line—Get Water onto a Ventilated Fire Fast” section at the very end of this page) would be 600 G.P.M. for 50% involvement of a 3,600 square-foot space—plus 25% more for each floor above the fire and for each side with an exposure within thirty feet.

To remain well within these flow recommendations and estimates, and within realistic expectations of the capabilities of company staffing, a tactical alarm response should be structured within these limitations:

        • Buildings are no larger than one-family or two-family dwellings, two stories or less in height, with a floor space not exceeding 3,600 feet.
        • Using pressurized fire hydrants, the response has the capability of establishing an initial flow of at least 250 G.P.M., then improving that flow to not less than 1,000 G.P.M. to supply an offensive fire attack, or 1,500 G.P.M. or more for implementing a defensive strategy to contain a fire.
        • Hydrant spacing does not exceed 500 feet in the response area (the front of every dwelling parcel is within 250 feet of a hydrant).
        • The first-due engine company is within 1 ½ miles of the most distant dwelling in the assignment area and is reliably prompt—turnout time averaging one minute (career) to three minutes (volunteer).
        • The first-due engine company has a response (driving) time from their station to the scene of four minutes or less.

If these limitations cannot be met, then the use of a full first alarm assignment should replace a tactical alarm as the initial response to fires reported in one-family and two-family dwellings.  The speed at which modern fires reach flashover has now rendered obsolete many long-established standards for turnout and response times.  Based on the time factors alone, an initial response of a full first alarm assignment may be the only option for departments whose personnel respond from their homes.

Due to the synthetic fuel loads in modern homes, if a fire in a non-sprinklered dwelling is ventilated, even the best turnout and response times aren’t always good enough.  Today, a tactical alarm assignment may be a sufficient initial response only if a fire happens to be confined to a compartment with closed doors and windows.  Fire departments need to anticipate hotter faster-growing fires and upgrade their water supply and fire stream capabilities accordingly.  (Image courtesy of Home Fire Sprinkler Coalition)

Despite all the caveats, the tactical alarm assignment remains a valid and effective weapon in the response arsenal of many jurisdictions.  Urban departments have long known its success as a resource-thrifty operational tool.  Suburban and micropolitan districts with good municipal hydrant systems and career, combination, or live-in personnel may find a tactical response suitable for dwelling fires in their communities too.  Departments with less-than-ideal hydrant systems and/or delayed responses might still take advantage of the tactical alarm as an initial assignment for fire alarms, investigations, gas leaks, chimney fires, and other similar incidents.

Considering the speed at which modern fires reach flashover, and the greater heat release rates generated, tactical alarm assignments should be structured with contingencies in mind.  The tactical response needs to provide the total number of engine companies necessary to deliver both a primary and a secondary water supply for the leadoff and backup hoselines at the scene.  When summoned as an upgrade from a well-planned local alarm response, the balance of the tactical assignment should consist of the companies needed to fulfill the supplementary supply and backup hoseline obligations.  For offensive fire attacks, a minimum flow of 1,000 G.P.M. needs to be established.  To be prepared for defensive measures, a total flow of at least 1,500 G.P.M. should be made available at the fire building.

Then too, the back of the structure should never be neglected.  At least one engine company with a good water supply must get lines to the rear.  There, a ladder company’s assistance may be necessary when gates and fences need breached, porches and windows need laddered, doors need forced, and previously unseen occupants need rescue assistance.

An example of the deployment of a tactical response for an offensive operation in a hydranted area.
An example of the deployment of a tactical alarm assignment consisting of two engines and two ladders for offensive firefighting in a single-family or two-family dwelling.  Using large-diameter hose and hydrants on separate “loops” within the grid network of underground water lines, the engine companies have established a flow capability of at least 1,500 G.P.M. at the scene.  In a narrow alleyway, the second-in companies have taken positions behind the fire building.  Lacking an alley, driveway, or other access to the back of the building, the second-in ladder, and possibly the second-in engine, may have no better option than to locate on the front side of the structure, then make their way on foot to the rear.
An example of the deployment of a tactical response for a defensive operation in a hydranted area.
In this example, the same “two and two” deployment positions fire streams in a defensive configuration to confine the fire to a fully involved dwelling.  If necessary, an upgrade to a full first alarm assignment can provide engines to pump hydrants and lay additional lines to fill in the water supply at the scene.  Companies from this upgraded response or a greater alarm may be required for searches and extension checks in the exposures and to function as relief crews during the completion of extinguishment and overhaul.

Force multipliers for fire departments serving areas equipped with fire hydrants.

Force multipliers can provide some departments with the advantage they need to use tactical alarm responses in lieu of a full first alarm assignment for dwelling fires.

An engine company equipped with large-diameter hose (L.D.H.) can often supply itself autonomously using water from a pressurized hydrant to deploy leadoff or backup lines to fight a fire in a dwelling.  Due to its very low friction loss, L.D.H. forward laid from a hydrant by a single engine will often provide an adequate flow without immediate need to have a second engine take a relay pumping position at the plug.  (But, if you have an extra engine on the scene, it’s better to use it on the plug as a redundancy measure than to park it somewhere doing nothing!)  One 4-inch line, for example, has a flow performance equal to or better than that of dual 3-inch lines.  For flows up to 1,000 G.P.M., 5-inch hose can be particularly effective, losing only about 7 or 8 P.S.I. per 100-foot section—that’s 40 P.S.I. or less for a stretch 500 feet in length.

To deliver water at voluminous rates for fighting larger fires near areas blessed with “green top” (1,000 to 1,499 G.P.M.) and “blue top” (1,500 G.P.M. +) hydrants, 5-inch or 6-inch hose can be pumped by a relay engine on the plug to overcome the increase in friction loss inherent with the higher flows.  A closed relay using 5-inch or 6-inch L.D.H. with in-line pumpers can transmit the flow and volume of hydrant and static sources to a fireground thousands of feet away.  When structuring response assignments in regions utilizing 5-inch L.D.H., a planner can safely count on each properly equipped engine company being capable of relay pumping 1,000 G.P.M. for a distance of 1,000 feet.

Friction loss for selected lays of five-inch fire hose.
To guarantee that a relay engine’s maximum flow capacity (100% at an engine pressure of 150 P.S.I.) is supplied to a receiving engine at an intake pressure of not less than 50 P.S.I. during a closed relay, the friction loss of the span of hose being pumped at that flow must not exceed 100 P.S.I. (red line).  To maximize water supplies, position relay engines so that the friction loss of the span of hose that each is pumping is less than 100 P.S.I. (don’t forget to add 5 P.S.I. for each increase in elevation of 10 feet).  To overcome friction loss higher than 100 P.S.I. in a given segment of a lay, an engine apparatus with a pump capacity exceeding the flow of the relay can be positioned to pump the supply line at an engine pressure greater than 150 P.S.I.  For example, an engine apparatus with a test flow rating of 2,000 G.P.M. at 150 P.S.I. can pump a span of hose having a friction loss of 150 P.S.I. using an engine pressure of 200 P.S.I. to deliver 1,400 G.P.M. (70% of capacity at 200 P.S.I.) to the receiving engine at a 50 P.S.I. intake pressure.  But remember, most L.D.H. is tested to only 200 P.S.I. and may be prone to failure above that pressure, so caution is in order.

From a single-engine local response through greater alarm assignments involving long-distance relay pumping, L.D.H. can be a force multiplier that reduces the number of apparatus needed to provide the necessary fire flow at the scene.  Its use can avail the fire chief with additional resources for performing other pertinent tasks on the fireground.

Many fire departments, particularly those in urban areas, operate quint combination pumpers as ladder companies.  Upon arrival at a fire, the personnel responding on the apparatus are responsible for ladder company tasks.  Engine companies lay hose, stretch attack lines, pump water, and supply the ladder pipe if needed.  The pump, booster tank, and most of the hose on the quint are there only as a backup—in case the engine operating with them breaks down or, for one of many reasons, the quint arrives at a fire scene and needs to operate as an engine for a period of time.  Quints are sometimes acquired to replace single-purpose ladders (aerial ladder apparatus without a pump and booster tank) so that the overall pump capacity of the department’s apparatus is sufficient for improving or maintaining a fire protection rating.

There are departments that have seized upon the multipurpose quint combination pumper to reduce the size of their apparatus fleet.  Some replace a traditional engine with a quint combination pumper, then eliminate a single-purpose ladder from their operation.  Others might replace a single-purpose ladder with a quint, then eliminate a traditional engine.  Some acquire a quint to replace both a single-purpose ladder and a traditional engine.  The only real difference between each of these replacement scenarios lies in the way the quint is to be utilized: primarily as an engine company, primarily as a ladder company, or as a company with a role determined by the location and particulars of each individual incident.

The maneuverable dual-purpose ladder or “dual pump ladder” (D.P.L.) is the workhorse of the London Fire Brigade.  D.P.L.s are found in every fire station and respond on every 999 emergency call (equivalent of 911) requiring a fire brigade response.  Depending on the needs of the incident upon their arrival, companies operating D.P.L.s function as either an engine company, applying water to extinguish the fire, or as a ladder company, filling rescue and support roles.  In American vernacular, D.P.L.s would be known as “quad” apparatus, equipped with a pump, a booster tank, hose, and an array of ground ladders including a 13.5-meter (44-foot) bangor ladder, but lacking the aerial device of a quint apparatus.  From the rear of the appliance (apparatus), the D.P.L.s bangor ladder can be systematically removed from its mount in a sliding deployment rack (top center of photo) by the well-drilled firefighters who are quite capable of quickly raising it to access third-story and fourth-story windows to effect rescues and extinguish fires.  American firefighters might be surprised to learn that less than 10% of the London Fire Brigade’s appliances are either “turntable ladders” or “aerial ladder platforms”.  (Public Domain image by Vera Kratochvil).

A quint can be a prudent replacement for a single-purpose ladder and/or traditional engine, or as an addition to an existing fleet, if the goal is to equip a department or company with an aerial apparatus that can enhance their capabilities by functioning as both an everyday engine and as an everyday ladder.  An adaptable quint combination pumper can be a force multiplier enabling not only urban, but many manpower-strapped suburban and micropolitan jurisdictions to use a tactical alarm assignment as a response to dwelling fires, particularly in areas where hydrant flow and spacing are adequate.

In these areas, select stations with some paid staff or live-in volunteers often get one apparatus on the road quickly and reliably.  They are the “go-to” company, an essential “core crew”, sometimes comprised of many individuals who collectively assure that the station is always ready, around the clock, for the next alarm.  Because these most responsive stations are typically located in the area’s more densely populated communities, they often operate large single-purpose aerial ladders.  Their turnout is so consistently prompt that they’re frequently summoned to provide mutual aid assistance to smaller suburban or rural departments—usually responding with the single-purpose ladder.  In return, they receive mutual aid responses in their first-due districts from these neighboring stations, mostly in the form of engine companies and additional manpower.  But a response from one crew per station is frequently all an assignment planner should expect from most combination or volunteer stations.  And that response from the smaller communities can sometimes be delayed.  This can create problems for a company that reliably responds to mutual aid alarms in a timely manner but does it with a ladder incapable of carrying or pumping water.  They can’t even cool and “reset” a fire or initiate a “holding action” (defensive-offensive strategy) until an engine arrives at the scene.  Within its own first-due area, the “core crew” must respond with an engine to assure that a water supply can be established, and a fire attack initiated.  They can’t sit there in a big ladder truck waiting for mutual aid engines from the smaller neighboring communities to show up and extinguish the fire.  But because they need to respond with an engine, the ladder may remain parked in their station, useless in their first-due district for lack of the manpower sufficient for staffing the turnout of a second apparatus.

Within its own first-due area, where an engine had been the first responding apparatus, the quint combination pumper could give this valuable “core crew” the added capability of…

        • using the aerial device upon arrival to effect a rescue, protect exposures, or cool and “reset” the fire if needed.
        • operating as a ladder company in any additional capacity.

A quint combination pumper could improve the effectiveness of this “core crew” in its neighboring response areas, where it had been using a single-purpose ladder, by providing it with the capabilities of…

        • establishing an autonomous water supply to fight a fire in a building within 500 feet of a hydrant.*
        • initiating an offensive fire attack—including cooling and “resetting” the fire if necessary.
        • initiating a holding action (defensive-offensive strategy).
        • initiating defensive containment of a large fire.
        • relay pumping a water supply for a previously arriving company.
        • operating as an engine company in any additional capacity.
        • continuing to operate as a ladder company in any capacity.

*Hydrant spacing should be 500 feet or less in the response area, and the quint needs to carry 500 feet or more of L.D.H. 

A quint combination pumper can provide a “core crew” with the flexibility they need for effectiveness on tactical alarm assignments.  During the deficient resource period that always precedes the arrival of the balance of a response, they can perform the first-in functions of the engine company or of the ladder company, as priorities dictate.  In their own first-due area, they no longer have to wonder if the community’s ladder truck will turn out if they take the engine to the fire first—they take their aerial-equipped quint combination pumper.  And on a mutual aid assist response, they no longer have to worry about arriving with a single-purpose ladder before there’s an engine company on the scene setting up to extinguish the fire—their quint combination pumper is an engine.  Their arrival with a multipurpose quint can lay the foundation for operations using any fire attack strategy.  Their versatility is a force multiplier, not only for their tactical responses to house fires, but for those to local, first, and greater alarm assignments as well.  The quint can be the “go-to” crew’s workhorse apparatus.

Sample deployment of a quint on a tactical response.
A sample deployment of a tactical alarm assignment consisting of a quint combination pumper (first-in) and two engines for offensive firefighting in a single-family or two-family dwelling.  Companies have laid large-diameter hose from hydrants on separate “loops” within the grid system of underground water lines to rapidly establish a flow of at least 1,500 G.P.M. at the scene, effectively eliminating water supply as a strategic factor for this incident.  To provide additional manpower for engine company, ladder company, and support functions, this tactical response could include additional apparatus.  A third engine, for example, might be used to pump the quint’s supply line and engage in pertinent fireground tasks.  To perform ladder company functions in districts without nearby aerial apparatus, extra engine and/or rescue squad companies might be included on a tactical response.  On the fire scene, a chief should use size-up and progress reports to determine if companies beyond those on the tactical assignment may be needed to mitigate the incident.  A prompt upgrade to a first alarm or greater should be transmitted to address any significant deficiencies.

First Alarm Assignment—Hydranted Districts

The first alarm assignment, known colloquially as a box alarm, fire box, or simply a “box”, is the unabridged full-sized initial response to a building fire.  It is often the upgraded response from a local or tactical alarm assignment, particularly when a structure larger than a single-family or two-family dwelling is found to be involved in fire.  It is the default initial response for all dwelling fires when inadequate water supplies, staffing, and other parameters foil the use of a tactical alarm assignment.

As a strategic-level response, a first alarm assignment must include the number companies necessary to provide a chief with sufficient manpower, apparatus, and equipment to employ the most appropriate of the fire attack strategies to initiate operations and begin meeting rescue, fire control, and property conservation objectives.

For offensive strategies, companies must be able to deliver a minimum initial water supply of 250 G.P.M. from a pressurized fire hydrant to the scene.  That flow must be improved to 1,000 G.P.M. to assure ample supply for the Direct Attack on the main body of fire—which may require as many as three or more hand-held hoselines and/or use of a master stream device to complete.  Backup and other supplemental supplies should be capable of developing an aggregate flow of not less than 1,500 G.P.M., the minimum fire flow required by both the I.S.O. and the International Fire Code for all building fires.

Flow requirements for first alarm assignments.

The Minimum Fire Flow is 1,500 G.P.M. for fires involving all buildings other than one-family and two-family dwellings that are two stories or less in height with a floor space not exceeding 3,600 square feet.

While establishing the necessary fire flow for a burning building may sound as simple as laying hose from several hydrants with collective test values that total the desired flow, then opening the plugs and charging the hose so that engines on the other end can pump the water onto the fire, it’s not always that easy.  Unfortunately, a chief must guard against “robbing Peter to pay Paul”.

Using additional hydrants doesn't guarantee an improvement in fire flow.
First alarm assignments in hydranted districts should include a sufficient number of engine companies for beginning the process of establishing an aggregate fire flow at the scene that meets the supply needs of the building(s) involved in fire.  Using more than one hydrant on a single loop of underground secondary feeder water lines (A) may provide water to multiple pumpers at the scene, but it doesn’t necessarily guarantee that the test flows of each of the individual plugs will be realized.  On dead end water lines (B), especially those that are secondary feeders less than eight inches in diameter, the situation is worse.  The fire flow at the scene stands little chance of exceeding the test flow of the best hydrant on the water distribution line, no matter how many plugs are used.  Unless a hydrant on a separate “loop” within the grid system of underground water lines is selected for each hoseline laid, significant increases in fire flow and maximization of the available water supplies will not be realized.  A first alarm assignment should be planned with provisions for the longer lays of hose and the relay pumping that may be needed to establish additional water supplies to not only back up the initial source(s) but improve fire flow as well.

While structuring response assignments, it’s important to plan for the extended hose lays that may be necessary to establish secondary (backup) and other supplemental water supplies within hydranted districts.  While the hydrant closest to the fire is usually the first to be used, selection of subsequent sources requires some knowledge of the water distribution network.  The number of engine companies en route on the initial response must be adequate to assure that, when necessary, a hydrant on a separate “loop” within the grid network of underground water lines can be used for each additional supply that needs to be established.  Selecting hydrants each separated by an intersection of three or four converging distribution lines provides better assurance that the test flow of each plug can be added to the aggregate fire flow delivered to the scene.  Where secondary feeder lines make up a majority of the water distribution grid, this technique of selecting hydrants may be a necessity for every plug used.  Conversely, in areas having a hydrant system with loops of large mains each capable of providing the fire flow required by the buildings in their proximity, a planner may be relieved of the necessity to prepare for these contingencies, particularly when creating the first alarm response.

First alarm assignments should include enough personnel to quickly begin the process of searching affected properties and, when and where necessary, removing endangered occupants.  To defend the search and rescue effort from the effects of a fire, engine companies need to secure water supplies and deploy fire streams to contain the blaze and protect egress routes.  Responses should be planned so that engine companies intended for water supply and water application are not routinely diverted to other functions.  In many jurisdictions, two companies are included on first alarm assignments for the purposes of extending searches, isolating the fire, controlling the ventilation flow path, and performing various support functions—usually two ladder companies or, as an alternative, a ladder company and a rescue squad company.  In districts populated with primarily single-family dwellings, response of a single ladder or rescue company may be deemed satisfactory, but “box areas” comprised of buildings that pose extraordinary life safety hazards may require inclusion of a third company for search, rescue, and support.  In regions where ladder companies are few and far between, or are absent altogether, a planner need not be overly discriminating in his/her selection of resources for inclusion in a response assignment.  Extra engine companies, rescue squads, or utility vehicles can be included on the first alarm response in sufficient quantity to assure that adequate forces are available to begin search, rescue, and evacuation tasks without diminishing the manpower levels needed by engine companies to perform fire suppression functions.  For each individual “box area”, the closest available sources of manpower should be considered for utilization, sometimes without regard for the type of apparatus they’ll use for the response.  To provide support staffing when the turn out of a shiny red fire truck may not always be a sure thing, a response planner may need to be content with firefighters and their personal protective equipment traveling in a fried-out Kombi, rusty pickup, or other “inferior” vehicle to reach the scene.

An example of the deployment of a strategic response for an offensive operation in a hydranted area.
An example of the deployment of a first alarm assignment consisting of four engines and two ladders is engaged in an offensive firefighting operation.  To initiate the fire attack, both the first-in engine and second-in engine have laid large-diameter supply lines from “orange top” (500-999 G.P.M.) hydrants, each on a separate “loop” within the grid system of underground water lines, to establish a combined flow capability of at least 1,000 G.P.M. at the fire building.  Using a relay pumping configuration, the third-in and fourth-in engine companies have established an additional supply of at least 1,000 G.P.M. from a hydrant on yet another separate “loop” in the grid.  Companies fighting the fire now have at their disposal a flow rate of over 2,000 G.P.M.  If the hydrants used by the first-in and second-in engines had had higher flow, low pressure, or greater distance from the scene, or if supply hose with a diameter of less than four inches was being used, then the third-in and fourth-in engines may have instead been assigned to relay pump the lines from these hydrants to the engines at the fire.  Notice that the “orange top” hydrants on the dead-end secondary feeders are not used to improve the flow capabilities, though they could have been used as the initial water supply if they had happened to be the most proximal to the fire.

A response with the capabilities of assuring that a fire flow of not less than 1,500 G.P.M. can be established at the fire building not only gives the chief the option of using any of the offensive fire attacks deemed necessary, but also provides water to begin stretching hand-held hoselines into exposed areas of adjacent compartments or structures to check extension and initiate the defensive component of an offensive-defensive strategy.

An example of the deployment of a strategic response for an offensive-defensive operation in a hydranted area.
As a strategic-level assignment, a first alarm should provide the fire chief with the resources necessary to implement the most appropriate fire strategy for mitigating the incident.  Here an offensive-defensive strategy is employed to fight a structural fire that is threatening to extend to attached properties.  While the first-in and second-in engine and ladder companies commence an attack on the main body of fire (offensive component), personnel from the third-in and fourth-in engine companies secure increased flow capabilities for the scene, then advance one or more hand-held hoselines into each of the units adjacent to the building of origin to stop extension (defensive component).  In many cases, one or more additional alarms will be necessary to complete the defensive component of this strategy, particularly in multiple dwellings or contiguous structures that are larger than row homes.  Remember, primary and secondary searches need to be completed not only in the fire building, but in all of the exposure buildings as well.

First-in companies may be faced with a large fire that exceeds their immediate capabilities of employing a successful offensive attack.  However, such a fire may be deemed to be within the offensive capabilities of the response upon the timely arrival of the balance of the first or second alarm companies.  Therefore, a first alarm assignment should be structured to allow the first-in companies to quickly establish a water supply to initiate a “holding action”—a defensive-offensive strategy—to contain the fire, evacuate threatened occupants, and prevent extension (defensive component) to buy time until additional companies arrive to provide the forces and/or fire flow needed to begin the Direct Attack on the main body of fire (offensive component).  Again, the response needs to include the resources needed to deliver an initial fire flow of not less than 250 G.P.M. to the scene, then improve that fire flow to a minimum of 1,500 G.P.M. or more.  For defensive-offensive operations, a second or greater alarm response is often required, not only for increasing the aggregate fire flow to greater than the minimum, but to assure that enough manpower, apparatus, and equipment is available to complete the offensive attack and assure the safety of the building’s occupants.

An example of the deployment of a strategic response for a "holding action", a defensive-offensive operation, in a hydranted area.
An sample deployment of a first alarm assignment comprised of four engines and two ladders to initiatie a “holding action” (a defensive-offensive strategy) to contain a large fire in stockpiles of combustibles stored outdoors along the rear wall of a fully-sprinklered commercial building.  In this example, the first-in engine company has secured a water supply, completed hook-ups to begin supporting the sprinkler system, and, using this initial supply, stretched not more than one 2 1/2″ hand-held hoseline into the building to check fire extension.  The second-in engine company has established a water supply from a hydrant on a line fed by a separate “loop” within the underground water distribution grid and has stretched a second 2 1/2″ hoseline to stop fire extension.  Additionally, if the supply from their hydrant is adequate, the second-in engine company may attempt to position a “step gun” (unmanned if necessary) to both help protect the rear wall of the building from impinging flames and, if conditions permit, intermittently cool the fire.  The ladder companies in this example are searching the building for fire and occupants while their driver-operators begin getting the aerial apparatus into position for the offensive attack on the fire.  Because the burning fuel is located outdoors, this is one of the rare scenarios where a Direct Attack with a flow exceeding 1,000 G.P.M. might be undertaken without undue risk to firefighter safety.  The Direct Attack is commenced using ladder pipes supplied by the third-in and fourth-in engine companies, each seen here laying large-diameter hose to provide a flow exceeding 2,000 G.P.M. for the effort.  Upon their arrival, engine companies from a second alarm could be assigned to pump the supply lines at the plugs selected by the third-in and fourth-in engines.  Other companies might establish additional water supplies for the hand-held hoselines and master streams that may be needed to either complete the offensive effort or begin cooling the exposure(s) and supplementing the flow to the sprinkler system if the attack fails to make progress.  (Note: For structures with lumber, pallets, and other combustibles stored along outer walls, many jurisdictions are adding 2,000 G.P.M. or more to the fire flow requirements for the hydrant systems serving the buildings.  For the building in the example shown here, that value would be added to the flow calculation for the sprinkler system and its hose stream allowance.)

For structural fires requiring a defensive strategy, a first alarm assignment with the capability of improving an initial minimum fire flow of 250 G.P.M. to a minimum of 1,500 G.P.M. or more gives a chief a broader choice of options for selecting the fire streams he/she needs to initiate operations to protect savable victims and property.  Hand-held hoselines may be necessary for securing escape routes for the evacuation of occupants from affected areas and for maintaining the tenability of places of refuge.  They may also be placed to prevent fire extension and extinguish fires both outside and inside exposure buildings.  Sprinkler systems need to be supported in all affected buildings so equipped.  Also, the ability to get at least one master stream device flowing soon after arrival improves the likelihood of cutting off the spread of the fire and protecting exposures.

An example of the deployment of a strategic response for a defensive operation in a hydranted area.
An example of the deployment of a first alarm assignment consisting of four engine and two ladder companies to initiate a defensive operation by cutting off fire extension resulting from radiant heat that is emanating from a fully involved commercial building.  Water supplies have been established and hand-held hoselines are quickly positioned to both cover the evacuation of exposure buildings and extinguish fires that are beginning to ignite their exterior surfaces.  When the affected area is clear of evacuees and firefighters manning hoselines, ladder pipes and master streams can begin flowing water to assume the role of cooling exposures and, if practicable, darkening the fire in the building of origin.  Greater alarms are of course necessary to begin backing up, supplementing, and filling in the supply to the fire streams that have begun the task of containing this fire.

To provide the aggregate fire flow that may ultimately be needed at the scene of a defensive operation, hydrants on separate “loops” in the grid of underground distribution lines will likely need to be used for each supply established.  Extremely large fires or conflagrations can easily exceed the capacity of a hydrant system—thus necessitating the use of relay pumping from what might otherwise be considered “rural” water sources such as streams, lakes, and rivers to improve flow and meet volume requirements.  A review of Emanuel Fried’s general plan of attack for defensive operations from Fireground Tactics (1972) reminds us of the quantity of hoselines that might be necessary for containing and finally extinguishing a large fire…

    1. The initial line placement heads off the fire spread.
    2. Then, the sprinkler system should be supplied. (fire building and exposures)
    3. Place additional lines so as to surround the entire fire area.
    4. Back up those hose lines in heavily involved areas or where men may be in danger.
    5. Fill in the supply to elevating platforms, ladder pipes, standpipe and sprinkler connections.
    6. Assign a spark and brand patrol if needed.

The need for greater alarms to furnish the equipment and manpower commensurate with establishing and sustaining water supplies to meet these needs is self-evident.

Level one and level two staging for a sample fire incident.
The practice of apparatus staging endows a fire chief with options for deploying companies to those parking and operating positions at the fire building that possess the greatest tactical advantage.  In many jurisdictions, each company on a first alarm assignment autonomously chooses a staging position one or more intersections away from the scene, but still along its response route.  This practice is known as “Level One Apparatus Staging”.  Companies arriving with pumping apparatus typically select a staging location at a water supply that might be of potential use.  Most departments using a “Level One Apparatus Staging” system in a district equipped with pressurized fire hydrants will, as a standard operating procedure, prescribe that the first-in engine company should secure a water supply and, along with the first-in ladder, proceed to a favorable placement position at the fire building.  Greater alarm assignments, if needed, are dispatched to respond to a “Level Two Apparatus Staging” area: a parking lot, side street, or other location where apparatus can be assembled as a tactical reserve and afforded multiple approach routes to the fire scene.  To be most effective, the “Level Two Apparatus Staging” area should be designated during the call for a second alarm assignment and a staging officer should be appointed to operate as a liaison with the command post for all its communications.

Greater Alarms—Hydranted Districts

Every “box area” should have responses planned for second through fourth, fifth, even eighth alarm assignments or more.  It’s much better to make these preparations ahead of time rather than letting dispatch personnel in the dark during a really big incident trying to figure out which companies they need to send to the scene, to the staging area, or to cover-ups at fire stations.

Greater alarms, beginning with the second alarm assignment, vary in intent and size from jurisdiction to jurisdiction.  In some smaller career departments, the second alarm does little more than summon off-duty firefighters to staff a piece of reserve apparatus.  In other departments, the response on each greater alarm functions as a task force composed of pumping apparatus, hose, manpower, and possibly an aerial ladder—each intended to establish a water supply, improve fire flow, and operate a master stream if needed.  Still other departments structure greater alarms to add apparatus, manpower, special equipment, and other resources to a “Level Two Apparatus Staging” area—a tactical reserve from which companies can be quickly deployed when and where needed, either individually or as a task force or other group.

Some large departments strike a “general alarm” to summon any and all on-duty and off-duty firefighters to the scene of a fire for which all other resources, on all organized alarms, have already been committed.  Structured responses from mutual aid companies may or may not be among a department’s plans to supplement resources following the transmission of a “general alarm”—this too, varies by jurisdiction.

Greater alarms should provide the resources needed to sustain the fire strategy initiated by the companies on the first alarm assignment.  Additionally, these responses should include companies capable of preparing contingencies for any changes that may be required in the operational plan.  For many incidents, particularly those being mitigated with an offensive fire attack, greater alarms may be summoned solely to provide manpower.  But for bigger fires, especially those with significant life safety hazards and/or requiring large fire flows and multiple heavy fire streams, greater alarms may need to provide a wider spectrum of resources.

To eliminate the guesswork involved with trying to anticipate the apparatus and manpower needs for every conceivable incident that might require a greater alarm assignment in a given “box area”, a planner should strongly consider the advantages of using each response, beginning with the second alarm, to build and maintain a tactical reserve in a “Level Two Apparatus Staging” area.  During an offensive operation, companies from this reserve might be summoned to the scene solely to provide a manpower pool for the relief of first alarm crews, for completing searches, and for beginning salvage and overhaul.  Extensive offensive operations, such as those implemented to fight fires in high-rise buildings, can benefit from having a ready reserve of companies available for manning hoselines, conducting searches, effecting rescues, transporting equipment to upper stories, and relieving fatigued crews.  During fires involving row homes or other contiguous structures, companies could be forwarded from the staging area to the scene and tasked with advancing lines into exposure buildings to extinguish fire and check extension as participants in the defensive component of an offensive-defensive strategy.  For each of these deployments, and certainly for any defensive operation, the tactical reserve should have companies standing by that are capable of establishing a supplemental water supply to improve the aggregate fire flow at the scene or replace a supply that has been compromised.

An example of the deployment of a second-alarm assignment for an offensive-defensive operation in a hydranted area.
From a “Level Two Apparatus Staging” area, second alarm companies have been deployed on this offensive-defensive operation to improve the fire flow at the scene to more than 3,000 G.P.M. and advance additional hand-held hoselines into exposure buildings to check fire extension and begin salvage and overhaul.  Increasing the aggregate fire flow provides water that may be needed for contingencies such as ladder pipes or other exterior fire streams if the attack fails and a revision of the strategy is necessary.

Each greater alarm assignment may include engine, ladder, rescue squad, and service companies to provide support capabilities and extra manpower for the operation.  Some jurisdictions might exclude ladder companies from the third and subsequent greater alarm assignments, preferring to get the aerial apparatus positioned early—on the first and second alarms.  Others, particularly those with response areas comprised of high-rise or other large buildings, include ladder companies, and oft times rescue squad companies, on each response—not necessarily for the apparatus, but for the skills of the members.  If not summoned previously, at least one breathing air/mask service unit is usually included on a second alarm assignment.  Greater alarms might also include communications vehicles, rehab equipment, canteen service, and specialized equipment that might not be used on lesser incidents.  Response areas comprised of manufacturing, chemical storage, heavy industrial, or other similar occupancies may include hazardous materials teams and/or foam equipment on greater alarm assignments.  Some jurisdictions, however, will “special call” such companies only when needed—placing them on a resource file for each “box area” instead of on the dispatch list for any of its response assignments.

To address massive fires, the ability to lay supply hose and pump water is the paramount consideration for structuring and organizing greater alarm responses—that means engine companies.

Fire flow goals for greater alarm assignments.

The fire flow requirements for buildings larger than single-family or two-family dwellings can seem daunting.  During defensive operations, engine companies on greater alarms may be required to establish supplies from additional sources to increase the total fire flow at the scene to that required by the building(s) involved in fire.  For “habitational buildings”, loosely defined as apartment, condominium, dormitory, and other similar domiciles, the maximum Needed Fire Flow prescribed by the I.S.O. is 3, 500 G.P.M.  For most fire departments, this is the “Basic Fire Flow”, as determined by the I.S.O., for their hydranted districts and is the flow used to determine their Public Protection Classification rating.  For a community to deliver this “Basic Fire Flow” to the buildings that may need it, the hydrant system must be capable of flowing 3,500 G.P.M. for at least three hours, and the fire department’s pumping apparatus and hose needs to be able to move that water to the fire.  Unless the community has an abundance of “blue top” (Class AA) hydrants well-distributed throughout its response areas, the first alarm assignment alone will not be capable of establishing a “Basic Fire Flow” of 3,500 G.P.M., or an even larger flow, should it be required.  Therefore, the response of an adequate number of engine companies on each greater alarm becomes a necessity.

A gravity tank on a public water supply distribution system.
If maintained by the water utility at 85% of capacity or more, a 750,000-gallon gravity tank could supply a hydrant system with the maximum needed fire flow for “habitational buildings” as recommended by the I.S.O. (3,500 G.P.M. for a period of three hours).

Because a community’s “Basic Fire Flow” represents its fifth highest Needed Fire Flow as determined by the I.S.O. formula, a response planner is likely to discover buildings within his/her district that have significantly larger flow requirements, possibly as great as the maximum of 12,000 G.P.M.—a flow which few departments have any hope of delivering to the scene without the help of a fire tug pumping from a river or bay.  To determine the water supply needs for each of a jurisdiction’s response areas, a planner must determine the highest fire flow requirement for each.  Calculating the Needed Fire Flow for its largest buildings will provide the planner with an accurate assessment of a “box area’s” demands.  (Note: Buildings with Needed Fire Flows that are significantly greater than their community’s Basic Fire Flow are often evaluated separately by the I.S.O.—many having their own fire protection systems, water supplies, and fire brigades.  Though the fire department and local hydrant system aren’t graded on their ability to deliver the requisite flows to these buildings, they still might be called upon to fight a fire involving them—so preparation is a must.) 

To make it easier, comparable fire flow requirements for individual buildings can be determined, without the need for the lengthy I.S.O. calculations, by consulting the International Fire Code’s Appendix B: “Fire-flow Requirements for Buildings”.  By referencing Table B105.1: “Minimum Required Fire-Flow and Flow Duration for Buildings”, knowledge of a building’s construction type and size in square feet can be used to find its fire flow needs and the length of time in hours that that flow must be sustained.

Greater alarm assignments are often used to improve aggregate fire flow for defensive measures—extension control during offensive-defensive attacks and especially fire containment during defensive operations.  A fully developed fire engulfing an entire structure will produce a building’s maximum heat release rate—requiring an equal heat absorption capacity from fire streams if extinguishment is to be achieved.  A response planner should not be surprised to discover that fire flows from nearby sources fall far short of the requirements for the largest buildings in a district, particularly in older communities.  Whether in the biggest or in the smallest buildings, fully developed fires that have grown to a size exceeding the cooling capacities of fire streams must be contained defensively by prudent use of the fire flow that is readily available for delivery to the scene.  The protection of exposures and the control of fire extension can give way to extinguishment of the main body of fire during the vented (final) decay phase as the burning fuel’s heat release rate diminishes to within the cooling capacity of the fire flow that has been established.

Each greater alarm assignment should provide pumping apparatus sufficient for developing at least one new water source for supplying hoselines to cut off the fire’s spread, support a sprinkler system, surround the fire area, backup existing positions, or fill in the supply to master streams or fire protection systems.  For each” box area”, a planner needs to make an estimate of the maximum distance that supply hose will need to be laid in order to access additional water supplies that improve the total fire flow and assure its continuity at a fire scene.  This distance is likely to increase progressively for each new supply that is established, requiring additional apparatus to relay pump from hydrants or from suction points on static sources such as lakes, streams, rivers, or bays.  For really lengthy lays, in-line relay pumping could be necessary as well.

A static water supply for rural firefighting.
Just like in rural areas, suction points on static water sources can be used to improve fire flow and increase the volume of water available to fight a massive fire in a hydranted district.  For every foot of depth, a one-acre lake can provide more than 300,000 gallons of water.  For improving the aggregate fire flow at the scene, that’ll supply a configuration of relay pumpers with 1,500 G.P.M. for more than three hours.  This particular stream-fed lake with a pumpable depth of greater than five feet could provide 4,000 G.P.M. or more for the requisite four-hour time duration, so line up the drafting engines!

When creating greater alarm assignments, a planner considering the distance from potential water supplies to possible fire scenes may need to include more than two engines for each relay operation.  The amount of supply hose carried and its friction loss are the primary limiting factors affecting the distance over which a given fire flow can be delivered from a water source to the apparatus at the scene.  It’s important to understand some basic distance limitations of common hose lay configurations.  Two engine companies (one at the source and one at the scene) equipped with 1,000 G.P.M. pumps and using a dual 3-inch or a single 4-inch supply hose layout could relay a flow of 800 G.P.M. a distance of up to 800 feet from a water source to a position at the fire.  Using 5-inch supply hose, 1,000 G.P.M. could be relayed to a fire up to 1,000 feet from the water source (being really conservative here—1,400 feet is certainly doable).  For distances exceeding these, an additional engine is needed at an in-line pumping position between the original two in the configuration.  To assure that the flow is delivered to the fire, in-line pumpers should be placed so that no span of hose in the relay exceeds the length of that given for the two-engine configuration.  For example: three engines—one at the source, one at an in-line position, and one at the scene—could relay pump 1,000 G.P.M. a distance of up to 2,000 feet from a hydrant or other water source to a position at the fire scene.  Therefore, four engines could relay pump 1,000 G.P.M. for a distance of up to 3,000 feet, five engines up to 4,000 feet, and so on.  A planner can count on increases in these distances and/or flow rates if the engines used for relay operations carry adequate hose and either have pump capacities larger than 1000 G.P.M. or provide a residual (intake) pressure of less than 50 P.S.I. to a receiving pumper.  But for preparing response assignments, the basic figures are reliable, easy to use, and will assure that there is allowance for the unexpected—after all, it pays to be conservative.

Relay pumping.
In each of these examples, the maximum length of the span of hose between the fire attack pumper (left) and the source pumper (right) can be increased by insertion of an in-line relay pumper.
Relay pumping.
An example of a closed relay that a greater alarm assignment may be capable of establishing.  A planner can organize responses according to these minimum capabilities and be confident that advantages such as higher pump capacities will lead to even better performance and an increase above the listed parameters on the fireground.  (Helpful hint: position the highest capacity pumper at the water source.)

Whether you’re planning your responses to function as individual task forces—one on each alarm—or you’re intending them to populate a “Level Two Apparatus Staging” area as a tactical reserve, having multiple engine companies on each greater alarm assignment is a priority.  A planner who determines that two engine companies may be sufficient for securing supplemental water supplies on the second and third alarms, but that three or more might be necessary on assignments thereafter, may be wise to include additional engines on the earliest responses too.  They could certainly be used to furnish extra manpower, to pump hydrants for the first-in units, to deploy additional fire streams, or to add to the tactical reserve in the staging area.  Inclusion of three or four engine companies on each greater alarm assignment, particularly when a “Level Two Apparatus Staging” area is in use, can provide a fire chief with operational flexibility—and the assurance that pumping apparatus capable of improving the fire flow at the scene is close at hand.

Editor’s Note: Some jurisdictions create “Closed Relay Task Force” and/or “Open Relay Task Force” responses that are organized independent of the typical alarm assignment hierarchy.  Most consist of engine companies with 2,000 G.P.M. pump capacities, 5-inch or larger supply hose, and, for the latter, large porta-tanks.  Some operate regionally, drill extensively, and include oversize master stream devices on their response roster. 


Water Supply

—Response Assignments in Rural Districts

An old fire hydrant with just one yard connection.
Some jurisdictions may have hydrants capable of flowing the 250 G.P.M. minimum needed to initiate a fire attack but need supplemental water to fully contain and extinguish a fire.  Response areas where pressurized hydrant systems are absent or fall short of the fire flow requirements for the buildings located therein are deemed “rural districts”, demanding response assignments that summon the equipment and personnel necessary to promptly establish adequate water supplies by the most suitable alternate means.  Options include tanker/tender nursing, tanker/tender water shuttle, relay pumping from a static source, and relay pumping from a distant pressurized hydrant system.
A sample of the sequential upgrading process for assignments in a rural “box area” for which a tactical-level response for fires reported in single-family and two-family dwellings is included as an economy of force measure.  In this example, a chief requesting an upgrade from a local alarm directly to a first alarm would receive the balance of the companies due: three more engines, one ladder, and two additional tanker/tenders.
A sample of the sequential upgrading process for assignments in a rural “box area” for which a reduced strategic-level response is utilized as an economy of force measure for a reported building fire.  Many jurisdictions use an “all hands” or “working fire” upgrade to bolster the response for handling structural fires requiring extensive offensive attacks or offensive-defensive operations.  In the example shown here, a chief requesting an upgrade from a local alarm directly to an “all hands” or “working fire” assignment would receive the balance of the companies due: an additional three engine companies, two ladder companies, and three more tanker/tender companies.  Suppose a fire chief has transmitted a call for a second alarm to improve the fire flow at the scene of a defensive operation.  He/she would receive the four engine companies, two ladder companies, and four tanker/tender companies collectively due on the local, first alarm, and “all hands” assignments, plus the companies due on the second alarm response.

Local Alarm Assignment—Rural Districts

More to follow on this topic soon.

Tactical Alarm Assignment—Rural Districts

More to follow on this topic soon.

First Alarm Assignment—Rural Districts

More to follow on this topic soon.

Greater Alarms—Rural Districts

More to follow on this topic soon.


The Strategic Pre-Fire Plan

—A Quick Reference for Initiating Fire Attack

More to follow on this topic soon


Hose Loads and Hydraulics

—Plan Ahead

Do your drivers understand fire service hydraulics well enough to develop reliable fire streams and water supplies on the fireground?  Does your department drill with various water supply and hose/appliance layout scenarios?  Does your fire department know the flow rates, friction loss, and required engine (pump discharge) pressures for its pre-connected hoselines and other hose loads?  Do you know how many firefighters are needed to advance and operate a given pre-connected hoseline?  Do you know the cooling capacity (in megawatts) of your pre-connected hoselines?  For fighting compartment fires, are your pre-connected hoselines equipped with the proper nozzles to produce water fog suitable for gaseous layer cooling?  Are these same hoselines being pumped to provide a minimum of 100 P.S.I. nozzle pressure for gas cooling?  Do you know the volume of fire area your pre-connected hoselines can extinguish using an Indirect “Fog” Fire Attack to prevent a smoke or backdraft explosion?

A flow chart is an essential tool for making hydraulic calculations.

Inevitably, someone around your fire station will discover that you have been doing friction loss calculations, either on your own or as part of a pump operator’s class you are attending.  They will say to you, in front of an audience of peers, something similar to, “…you can’t waste time doing that math at a fire while the building burns down!”  And then the pathetic bully and his clan of submissive little munchkins will share in a brief nervous chuckle.   Please do not be rattled or discouraged by such an individual.  You see, he can’t help himself.  Particularly in volunteer stations, these are often the members who see their primary role as being the indispensable fire truck driver.  They often defend that role ferociously against what they perceive as a threat.  If you’re lucky, you’re still just a hose-stretching grunt firefighter while gaining hydraulics competency.  However, if you reach the time when you’d like to become an apparatus operator, and you’ve noticed that this loudmouth is lacking numerous essential skills in front of the pump panel (you’ll know), and you find that he would be responsible for your “training”—well, let us just say that there are other fire stations around, so plan ahead.

“Fahrenheit 451” (1951) by Ray Bradbury is a classic novel about a nightmarish dystopian future when the sole duty of firemen is to break down doors, confiscate books, and burn them.  Perhaps you should read it as a bedtime story to your firehouse bully.  He may find it to be a soothing utopian dream!

Conversely, you may be lucky, and you may have a member possessing a vastly different mindset discover that you are doing your calculations.  And that person might say, “…you can’t waste time doing that math at a fire while the building is burning down, I’m glad to see that you’re doing it now!”  This may very well be the elusive and increasingly rare “driver-operator”, a truly indispensable asset in any fire department, and someone with whom you should seek frequent conversation.

Because, you see, hydraulics is not at all a topic for which a class will provide you with complete competence.  You can learn the theory, principles, and methods in the class, then it is up to you to imbue the science of moving water into your firefighting psyche through frequent study, practice, and application.  Hydraulics may be the most ideal topic for advanced learning in the firehouse.  A culture of open-minded conversation coupled with field trials, experimentation, comparison, advanced instruction, drilling, and more conversation can lead to in-house expertise in the science of water movement.  And you’ll find that firefighters from such an environment don’t stand around ciphering mathematics problems while a conflagration builds, no matter what the bully would have everyone believe.  You see, they’ve already done their math and planned ahead.  They may have a few things memorized.  They could have little mental prompts to recall other things.  There could be, hidden on their person somewhere, a laminated quick-reference card with friction loss numbers and other critical figures.  You can be assured that they have their pre-connected hoselines and common layouts pre-calculated and possibly have their discharges labeled with the appropriate engine (pump discharge) pressure.  Their hose loads are hydraulically sound.  These loads are often comprised of a mix of those that are versatile and some that are very specific in purpose.  To eliminate operator errors on the scene of a fire, they may have gone so far as to configure their pre-connected hoselines with various lengths, nozzles, flows, and sizes, but with most sharing a common engine (pump discharge) pressure.  They innovate and continuously learn.  And the community they serve is better for it.

Examples of fire hose friction loss cards.
Pocket or wallet references with friction loss and/or flow figures are sometimes available from fire equipment vendors as complimentary items.  Fire departments can create and print their own custom cards and have them laminated for durability.
Here it is again…The IFSTA “Pumping and Aerial Apparatus Driver/Operator Handbook” Third Edition (2015) is also available without the aerial apparatus chapters as the “Pumping Apparatus Driver/Operator Handbook”.  Both contain the same fantastic information about hose loads and hydraulics including: hose and nozzle flow rates, theoretical pressure calculations, and fireground hydraulic calculations.  If you’re looking to prepare to be a driver-operator or you’re interested in widening your knowledge and skills, you can’t go wrong with this book.  It is a thorough well-illustrated masterpiece.

IFSTA’s Pumping and Aerial Apparatus Driver/Operator Handbook (or the Pumping Apparatus Driver/Operator Handbook) provides the methods, formulas, and instruction you’ll need to learn how to complete your own hydraulic calculations.  It includes a comprehensive selection of friction loss charts for various sizes of fire hose.  Directions for friction loss calculations using a wide variety of hose, appliance, apparatus, and elevation variables are presented with examples to ease you through the process.  Testing procedures for pumps, hose, and some appliances are also included.

Measuring nozzle pressure of a fire stream using a pitot tube and gauge.
A pitot tube and gauge are used to measure nozzle pressure.  The output in G.P.M. can then be determined by consulting a flow chart.  Conducting your own tests is the most accurate method of evaluating the flow capabilities of your equipment and checking the friction loss of your fire hose, but this can be a time-consuming endeavor.  Calculation formulas and charts can provide a satisfactory alternative in the absence of your own data set.

For use on the fireground, the handbook contains samples of pump charts and directions for the valuable “Condensed Q Formula”.  The latter can be used to quickly determine friction loss in 3-inch, 4-inch, 5-inch, and even 6-inch fire hose—in your head!  Both are indispensable to driver-operators who take the time to remain familiar with them.

Condensed Q Formula

Friction Loss in P.S.I. per 100′ of Hose = Q² ÷ Hose Diameter Divisor

Q = Flow in hundreds of gallons per minute (G.P.M. ÷ 100)

Hose Diameter Divisor for 3″ Fire Hose = 1

Hose Diameter Divisor for 4″ Fire Hose = 5

Hose Diameter Divisor for 5″ Fire Hose = 15

Hose Diameter Divisor for 6″ Fire Hose = 20

Perhaps you’d like to get some practice using your new skills.  Maybe you’d like to create a diagram of the hose loads, including pre-connected hoselines, on your department’s apparatus.  Having been curious about the questions found at the beginning of this section, you’d like to create a chart which includes the calculated answers to each, and you’d like to do it for all of the pre-connected hoselines on your equipment.  Well, it’s your lucky day…


Download and print the following files (there are nine of them) to create your own Pre-Connected Hoseline Reference and Planner.  The hose and nozzle comparison charts include friction loss calculations and Engine (Pump Discharge) Pressures for over 100 pre-connected hoseline configurations.  Plus, there’s useful information for each of these loads that you will not find in other similar references.  Click on them, print them, create a diagram of the hose loads on your apparatus, then reference the comparison charts to populate a blank hose and nozzle chart with the figures for each of your pre-connected hoselines.  You can also use the diagram and charts to experiment and make a plan for improved and more functional hydraulically-sound hose loads for your existing or new apparatus.

Hose and Nozzle Layout Chart thumbnail.
Click the image to view and download the introduction page and blank Hose and Nozzle Layout chart (PDF file).
Hose and Nozzle Comparison Chart thumbnail.
Click the image to view and download the blank Hose and Nozzle Comparison Chart (PDF file).
Click the image to view and download the PDF file.
Click the image to view and download the PDF file.
Click the image to view and download the PDF file.
Click the image to view and download the PDF file.
Click the image to view and download the PDF file.
Click the image to view and download the PDF file.
Click the image to view and download the PDF file.

You’ll see that each of the seven “Firefighting Hose and Nozzle Comparison Charts” provides calculations in the vertical columns for the following sets of pertinent information:

Nozzle Type: The type of nozzle attached to the pre-connected hoseline for this horizontal row of calculations.

Nozzle Size in Inches: The size of the nozzle attached to the pre-connected hoseline for this horizontal row of calculations—provided for smooth bore nozzles, omitted for others.

Nozzle Pressure in P.S.I.: The pressure at the nozzle outlet while water is flowing.  It is the remainder of Engine Pressure minus loss accumulated by friction, restriction, and altitude during the movement of water from the pumper to the nozzle outlet.  Fixed pressure (automatic) combination nozzles maintain Nozzle Pressure at a set value (often 100 P.S.I.) by using an internal coil spring to “automatically” adjust the outlet orifice size in response to changes in flow.

Nozzle Flow in G.P.M.: The volume of water being discharged from the nozzle outlet of the given size at the given Nozzle Pressure.

Nozzle Reaction (N.R.): The amount of force generated by the pressure and volume of water being discharged at the nozzle outlet.  Discharging a solid stream can produce a force 30 times greater than that experienced by firefighters flowing the same volume at the same pressure in a fog stream pattern.

Personnel to Advance Nozzle: The number of firefighters required to advance the flowing nozzle (to overcome the nozzle reaction only).  This data is useful for comparing the manpower requirements of various hose and nozzle layouts, especially when cooling capacities are considered.  Remember though, larger lines are heavier and less maneuverable; they may require additional personnel to advance compared to smaller lines with the same nozzle reaction.  Try this to make comparison easier—using colored pencil or highlighter, shade each of the blocks in this column according to the number of firefighters needed to advance the nozzle…

GREEN= 1 Firefighter (to 60 lbsf. force)

YELLOW= 2 Firefighters (61 to 75 lbsf. force)

ORANGE= 3 Firefighters (76 to 95 lbsf. force)

RED= 2 Firefighters in a fixed position only (96 to 110 lbsf. force)

Greater than 110 lbsf. force…GOOD LUCK …You’re gonna need it.

Hose and Nozzle Comparison Chart Color Coded for Manpower Needs Hose and Nozzle Comparison Chart Color Coded for Manpower Needs

Cooling Capacity in Megawatts (MW): The theoretical capacity of the given nozzle flow (based on the mass of the water) to reduce or absorb the heat energy produced by a fire.  A megawatt is a measurement of power—the rate at which energy is generated or at which it is used.  In our context, a megawatt is a measurement of the rate at which heat energy is generated by a fire (heat release rate) or at which a given water flow can use (absorb) heat energy from a fire (cooling capacity).   A megawatt is the equivalent of one million watts—an energy release or use rate of one million joules per second.

Calculate the cooling capacity of a fire stream.
You can easily make a quick estimate of the Cooling Capacity (theoretical) of a fire stream by dividing its flow in gallons per minute (G.P.M.) by six.  Then again, you can do it the longer way.  This example of the flow from a 1 3/8″ tip on a multiversal takes the value in G.P.M., divides it by sixty to convert it to gallons per second (G.P.S.), then multiples the G.P.S. value by ten to determine the Cooling Capacity (theoretical) of the stream.  The Cooling Capacity could be multiplied by the efficiency factor for master streams, 25% (0.25), to estimate the Adjusted Cooling Capacity, which would be about 20.8 MW.

Adjusted Cooling Capacity in Megawatts (MW): The theoretical capacity of the given nozzle flow (based on the mass of the water) to reduce the heat release rate of a fire, adjusted to reflect the application efficiency of fire streams.  Adjusted Cooling Capacities for straight stream water application are listed for each entry and are calculated at 50% efficiency.  Adjusted Cooling Capacities for water fog application are listed after the straight stream figure only for nozzles operated at 100 P.S.I. and are calculated at 75% efficiency.  The greater efficiency of water fog is an advantage gained by the small water droplet size produced at pressures of approximately 100 P.S.I. and greater.  A dagger behind a straight stream calculation indicates that the nozzle pressure is too low to produce the proper droplet size and velocity needed for effective water fog.  Water fog is at its greatest efficiency when applied into the heated gaseous layer of a fire.  Short pulse water fog may be the most efficient heat reduction tool of all, but its application is limited to flows not exceeding 150 G.P.M., as indicated by double daggers on the chart.  Simply put, the valve on a nozzle flowing greater than 150 G.P.M. cannot be opened and closed fast enough by the operator to produce a short burst of water fog.  It should be remembered that with application efficiencies probably around 25%, Adjusted Cooling Capacities for master stream nozzles are significantly lower than those for hand-held nozzles.  Also, poor application technique with any nozzle quickly reduces the efficiency of a fire stream below 20%, thus the listed figures should be considered to be maximums.

Heat release rate of fires.
Multiple items burning simultaneously in a space such as a room each add their individual energy output value, measured as heat release rate in megawatts (MW), to the total energy output value of a fire.  Given adequate combustion conditions, including oxygen supply, the heat release rate for two sofas burning in a room could be twice that of one sofa.  However, two sofas on fire instead of one does not have the effect of “doubling” the temperature.  The additional heat release rate produced by two burning sofas would certainly expedite the process of temperature increase in the atmosphere of the room.  But, because energy from the fire and heated ballast (smoke, fuel vapor, etc.) is absorbed by the mass of the walls, ceilings, and other furnishings, the temperature in the atmosphere is not likely to reach its maximum and possiby “double” until some or all of these surfaces produce their own energy by burning (i.e,. flashover).  Heat release rates from “Heat Release Rate of Burning Items in Fires” (2000) by Hyeong-Jin Kim and David G. Lilley, and other sources listed throughout this page.
Dry Christmas trees can burn with spectacular speed and produce nearly instant heat release rates ranging from 3.2 to 4.3 MW.  The National Institute of Standards and Technology (N.I.S.T.) study, “Impact of a Residential Sprinkler on the Heat Release Rate of a Christmas Tree Fire” (2008) by Daniel Madrzykowski, found that sprinkler activation limited the heat release rate from such fires to 1.8 MW and less.  Fire in a furnished room lacking sprinklers reached a post-flashover heat release rate of 6 MW.  All fires ignited in well-watered Christmas trees self-extinguished.  (N.I.S.T. Image)
Cooling capacity of selected nozzle flow rates for firefighting.
While vaporizing to steam, water absorbs an enormous amount of energy from a fire.  An adequate mass of water applied to a fire over a particular interval of time (adequate flow in G.P.M. for example) will absorb nearly all of the energy and in effect reduce the heat release rate to zero, thus extinguishing the fire.  The amount of energy (heat release rate) that a given Nozzle Flow (in G.P.M.) can absorb is its Cooling Capacity, and this value varies with the efficiency of water application.  During fire suppression, temperature reduction occurs as the heat release rate begins declining and energy still being produced by combustion is absorbed by the increasing mass within the space: the water and resulting steam.  Following extinguishment (and nullification of the fire’s heat release rate), the temperature continues to fall as energy dissipates into additional mass surrounding the fire area, including water and air flow introduced during overhaul.

Iowa Formula Coverage in Cubic Feet: The volume (in cubic feet) of a closed compartment space into which a water fog can be applied using the given nozzle to perform a defensive three-dimensional Indirect “Fog” Fire Attack to cool and knock down a decay phase fire in 30 seconds.  Again, a dagger indicates that a nozzle pressure is too low to produce the proper droplet size and velocity needed for effective water fog.

Friction Loss per 100′ Hose: The calculated friction loss in each 100 feet of fire hose of the given diameter for the nozzle pressure and flow listed.  The first figure is calculated using the adjusted field coefficients developed by Battalion Chief Sam Clark (see the introduction page).  These coefficients prove quite accurate for predicting the performance of modern fire hose in good condition.  The figure in parentheses is calculated using the traditional theoretical coefficients, which tend to be less reliable.

Engine Pressure 150′ Line: The Engine (Pump Discharge) Pressure required to supply the listed nozzle pressure and flow through 150 feet of pre-connected fire hose of the given diameter.  This is the pressure that the driver-operator should see and maintain on the Discharge Gauge corresponding to the Discharge Valve for the given pre-connected hoseline.  Again, the first figure is calculated using the adjusted field coefficients; the figure in parentheses is calculated using traditional theoretical coefficients.  When the nozzle is positioned at an altitude greater than the pump, the driver-operator will need to add 5 P.S.I. to the listed engine pressure for each story of elevation.

Engine Pressure 200′ Line: Same as above but calculated for 200 feet of pre-connected fire hose of the given diameter.

Engine Pressure 250′ Line: Same as above but calculated for 250 feet of pre-connected fire hose of the given diameter.

Engine Pressure 300′ Line: Same as above but calculated for 300 feet of pre-connected fire hose of the given diameter.

NOTE: You can easily add multiples of 100 feet of fire hose to any of these pre-connected lines to achieve greater lengths.   To amend the listed “Engine Pressure ___’ Line” calculation, add the corresponding “Friction Loss per 100′ Hose” value once for each 100′ extension.

The Master Pump Discharge Gauge (right) measures the pressure (in P.S.I.) of water leaving the fire pump before reaching individual Discharge Valves and Gauges.  It indicates the net increase in pressure above that of water entering the pump (shown on the Master Pump Intake Gauge to the left).  The pressure on the Master Pump Discharge Gauge is the maximum available to any individual discharge.  The Engine Throttle is adjusted to maintain the desired pump pressure as displayed on the Master Pump Discharge Gauge.
Discharge Gauges indicate the “Engine Pressure” (“Pump Discharge Pressure”), the pressure on the outlet side of each individual Discharge Valve where water enters hoselines or plumbing for fixed devices.  To make fireground operations less confusing, the Discharge Valves and Gauges on this particular engine are labeled and color-coded to match markings on the corresponding discharge fittings and pre-connected nozzles.  To make the driver-operator’s job easier, small stickers on the Discharge Gauges indicate the pre-determined “Engine Pressure” for that particular pre-connected hoseline.  The desired “Engine Pressure” for a given discharge as indicated on its Discharge Gauge can be maintained by adjusting the corresponding Discharge Valve while water is flowing.
Color-coded combination nozzles for firefighting.
You can color-code the nozzles on your pre-connected hoselines by wrapping colored tape around the shut-off bale, or you can spend some cash to get more formal and permanent.
Color-coded fire hose.
Got money to burn? You can purchase color-coded hose for each pre-connected line.  It will match the nozzle, the cover plates at the discharge, the Discharge Valve handle, and the Discharge Gauge.  Charging or shutting down the wrong line at the wrong time will be a thing of the past, unless of course two different engine companies each have a blue line stretched into the same fire building.  While you’re at it, you had better put a marking on each nozzle to indicate which company it belongs to!

3D Fire Fighting: Training, Techniques, and Tactics (2005) by Paul Grimwood, Ed Hartin, John McDonough, and Shan Raffel served as a reference for much of the nozzle reaction and cooling capacity data adapted for use in the “Firefighting Hose and Nozzle Comparison Charts”.


Using the Firefighter’s Pre-Connected Hoseline Reference and Planner, a modern hose load can be designed for an existing or new engine, quint, pumper-tanker/tender, or other apparatus.

In this example, information from the hose and nozzle comparison charts was used to create a hose load that is tactically prepared, hydraulically sound, and makes prudent use of limited manpower.  All pre-connected hoselines, with the exception of the 2-inch or 2 ½-inch structural fire cross-lay line, will operate effectively if supplied using an Engine (Pump Discharge) Pressure of 135 P.S.I.—making the pump operator’s job much easier.  These same pre-connected hoselines each have a nozzle reaction of less than 75 lbsf., meaning no more than two firefighters are needed to advance the flowing nozzle.  There are pre-connected hoselines equipped with nozzles suitable for effectively cooling the gaseous layer when fighting compartment fires.  There are other pre-connected lines which will produce the higher flow rates needed for tackling structural fires.  A pre-connected line on the front bumper can rapidly be placed into operation by one firefighter to initiate a “Fast Water” Structural Transitional Attack to cool and “reset” the fire before a crew advances to extinguish it.  On the images that follow, you’ll notice that the Adjusted Cooling Capacity in Megawatts (MW), as found in the comparison charts, is included for each pre-connected hoseline.

Sample supply hose and pre-connected hoseline load on a fire engine.
REAR: Compartment Fire Pre-Connect Lines, Supply and Hook-Up Hose, and a Step-Mounted Exposure Gun (Multiversal).  During a Pulse/3-D Transitional Attack, the Compartment Fire Pre-Connect Lines will provide water fog for gaseous layer cooling, as well as a straight stream for Direct Attack fire extinguishment.  The 100 P.S.I. nozzles provide suitable water fog for the Indirect “Fog” Fire Attack too.  These lines can also be used for structural firefighting, giving the nozzle operator the option of indirect cooling using water fog during door entry and the advance on the fire, but with some loss in maneuverability compared to a Structural Fire Pre-Connect Line with a lower nozzle pressure at the same flow.  The flow on these lines equipped with “automatic” fixed-pressure nozzles can be increased as needed by raising the Engine Pressure, but, again, at the expense of some mobility.  The 300′ long 2-inch Compartment Fire Pre-Connect Line could function as an extended hoseline for nearly any purpose.  For example, you can affix a 1-inch smooth bore nozzle to quickly convert it to a Structural Fire Pre-Connect Line flowing more than 210 G.P.M. with the same 135 P.S.I. Engine Pressure.
Sample hose load.
STREET SIDE: Structural Fire Pre-Connect Lines and the Deck Gun (the latter seen better in “curb side” image but detailed here).  To contain and extinguish fast-growing ventilated (structural) fires, Structural Fire Pre-Connect Lines are configured to operate at a lower pressure and higher flow than the lines used to initiate an attack on a compartment fire.  They can be ideal for use as back-up lines during any fire.  Always deploy backup lines capable of equal or greater flow than the line they’re backing up.  Structural Fire Pre-Connect Lines can be fitted with combination nozzles instead of smooth bore nozzles if desired.  However, be aware that hoselines with combination nozzles using a nozzle pressure greater than 50 P.S.I. are more rigid and less maneuverable at a given flow rate than a line equipped with a smooth bore nozzle producing the same flow rate at 50 P.S.I.  These lines are not intended for indirect gaseous layer cooling.  Remember, water fog becomes progressively less efficient when produced by combination nozzles operated at a pressure less than 100 P.S.I.  Also, at flows greater than 150 G.P.M., a nozzle operator cannot open and close a valve fast enough to produce a short burst of water fog.
Sample hose load.
FRONT: Hook-Up Line and a Structural Fire “Fast Water” Pre-Connect Line.  Okay, we cheated a bit…the N.R. would be a little higher at 79 lbsf., but one firefighter could still get this line in position quickly, then flow water to “reset” a fire.  It’s a manpower-efficient line with a punch!  If this line were to be advanced while flowing, two firefighters are necessary, and a third wouldn’t hurt.
Sample hose load.
CURB SIDE: Reserve Hose and a Rubbish Line.  The deck gun and cross-lays that can be seen here are detailed on the “street side” image.  Based solely upon nozzle reaction, all Structural Fire Pre-Connect Lines flowing 210 G.P.M. or less and all Compartment Fire Pre-Connect Lines shown in these “Sample Hose and Nozzle Layout” images can be advanced and operated by two firefighters.  However, additional personnel might be needed to move the charged hose, particularly the 2-inch or 2 1/2-inch lines, due to their weight and rigidity.


Selecting Hoselines for Fire Attack

—A size-up really is about size

The following is a collection of tips for selecting hoselines for use during a fire attack.  They are based upon formulas developed to estimate flow requirements for a cubic-foot volume of burning space (three-dimensional attacks) or square-foot area of burning space (two-dimensional attacks).  Each formula is specific to a particular type of water application.

Fire attack strategy and tactic(s) regularly determine fire stream selection and placement, but search, rescue, and evacuation requirements often influence the what, the when, and the where of hand-held hoseline deployment.

Our focus in the following paragraphs and images is primarily on the selection of hand-held hoselines for use with an offensive strategy to protect search and rescue by containing and extinguishing a fire.  Because it attacks and eliminates the main body of fire, the offensive strategy is the optimal method of assuring the safety of occupants.  But there may be incidents where hand-held hoselines are necessary as part of a defensive strategy’s life-saving effort.  Specifically, lines may need to be stretched to protect occupants from impinging fire that cannot be extinguished.  For this task, it’s important to select a line that can be maneuvered into a favorable position quickly, but not at the expense of a flow that will adequately cool the fire hazard.  If evacuations are to occur as part of a defensive-offensive (holding action) or defensive strategy, hand-held hoselines may need to be deployed rapidly to protect stairways, fire escapes, hallways, and other means of egress.  This may include the use of the larger caliber lines or even master streams.  When protecting evacuation routes, there is often an advantage to using hoselines equipped with combination nozzles; a wide cone of water fog can be used clear smoke from corridors, stairwells, and places of refuge—possibly preventing a panic.  During defensive operations conducted with limited water supplies, hand-held hoselines may be your best or only option for protecting exposures and controlling extension.

A hand-held hoseline is used to protect a fire escape egress route and "reset" a fire in a multi-unit building.
The Structural Fire Reset Line, as seen in the “Hose Load and Layout Samples”, can be expeditiously deployed to cool and “reset” a fire during a “Fast Water” Structural Transitional Attack, instantly improving tenability for victims still inside the involved building.  It can be used, regardless of the strategy, to intercede between the fire and porches, decks, stairs, and fire escapes where occupants may be attempting to evacuate or seek refuge from flame, heat, and smoke.

Your largest deployment of hand-held hoselines will probably occur when fighting a fire using an offensive-defensive strategy in a building or space having contiguous exposures (row houses, multiple dwellings, mixed-use structures, etc.).  After a sufficient number of lines have been advanced by first-in companies to cool and extinguish the main body of fire (offensive component), later-arriving “All Hands” or second alarm companies are assigned to stretch lines to extinguish fire and check extension in all exposed areas, including adjacent structures (defensive component).  Each of these lines needs to be capable of delivering the flow necessary for containing the fire that may be encountered.

In addition to advancing hoselines to protect rescue and conduct fire attack and extension control, fire protection features may need to be supplied, both in the fire building and in the exposures.

A fire department connection for an automatic sprinkler system.
Support the automatic sprinkler system immediately if smoke or fire is showing.  If there is no evidence of fire, hook-ups should be completed and conditions in the building should be evaluated prior to the lines being charged.  During offensive operations, complete your hook-ups and pump the system as the leadoff attack lines are being advanced.  Because, by design, automatic fire sprinklers contain fire and prevent extension, they can be a chief’s best friend during defensive operations.  Many large fires have been prevented from spreading building to building by the presence, activation, and support of the sprinklers inside an exposed structure.  Remember, their water supply may have been compromised by your firefighting efforts nearby, so be certain to pump these systems from adequate sources.
To utilize the full capacity of an engine company’s pump, the lines feeding a fire department sprinkler connection are usually supplied at 150 P.S.I., but there is an exception.  In some jurisdictions, fire protection systems go uninspected, and some may be in poor repair.  There are fire departments whose officers, fearing the possibility of destroying sprinkler plumbing by suddenly subjecting it to 150 pounds of pressure, take precautionary steps.  To reduce the strain on the valves and piping, driver-operators supply and maintain sprinkler systems at 125 P.S.I., a pressure still sufficient to provide adequate flow to activated heads.  In other departments, driver-operators routinely make a mental note of the static pressure on their line from the hydrant before pumping any water.  Then, if it is necessary to pump the sprinkler connection, they maintain it at close to the original static pressure while the status of the fire is evaluated.  If additional flow is needed, they increase the pressure to the sprinklers by small increments only.  Their logic is based on the theory that the system will be less likely to experience a plumbing failure if it is maintained close to the pressure, while flowing, that it may have experienced while at rest for decades.   Food for thought.

A Helpful Trick for Making Flow Estimates

A Helpful Trick- Familiarize yourself with the floor space on a single floor of a ranch-style house, apartment, or other dwelling that is 1,200 square feet in area.  Learn to visualize this space: 30 x 40 feet, 40 x 30 feet, 20 x 60 feet, 24 x 50 feet, and so on.  If you can imagine a building’s area or volume as a percentage or multiple of this space, it will make it easier to estimate flow requirements and select the proper hoselines for the job.

Hoselines for the Pulse/3-D Transitional Attack

The Pulse/3-D Transitional Attack relies upon fine water fog to cool and extinguish the three-dimensional gaseous component of a compartment fire during door entry and the advance to the main body of fire.  Therefore, a nozzle pressure of at least 100 P.S.I. is essential.  Flow is limited to 150 G.P.M. on the attack line due to the need to open and close the nozzle valve rapidly enough to produce short pulses of water fog.  Grimwood, in 3-D Fire Fighting; Training, Techniques, and Tactics, suggests 750 square feet as the maximum area for the Pulse/3-D method to achieve gaseous fire extinction.  Crews may be subjected to risks from rollover fire beyond their control along the wider fire front that may be encountered in a larger space.  Grimwood calculates a “3-D Cool Flow-rate” and a “Tactical flow-rate” of 113 G.P.M. for this maximum fire area of 750 square feet.  The “3-D Cool Flow-rate” is for the cooling of superheated gases encountered within the enclosure during the advance to the fire, and the “Tactical Flow-rate” is for the Direct Attack on the bed of fire within the cooled compartment.  To assure short pulse performance and adequate flow, hand-held hoselines used to conduct a Pulse/3-D Transitional Attack should therefore fall in the 115 to 150 G.P.M. range.  As always, backup lines, which are essential for every attack, should be capable of the same or greater flow than the line they’re backing up.

This Pulse/3-D Transitional Attack should achieve gaseous flame extinction and extinguishment of the fuel bed within a matter of minutes.  Evaluate the progress at least every six to ten minutes.  Remember to assign the later-arriving companies to check for accumulations of fire gases in compartments adjacent to, and even those not adjacent to, the one(s) involved in fire.  You’ve certainly heard of a fire in a cellar extending by superheated gases to the top floor or attic of a building while skipping the floors in between.

Pulse/3-D Transitional Attack on a compartment fire.
When cooling a compartment fire in its three-dimensional gaseous state, the Pulse/3-D Transitional Fire Attack is effective within an enclosure measuring up to 750 square feet in area with a ceiling approximately 8 feet high.  It’s easy to remember; that’s just over half the area on one floor of a rancher.  Each of the Compartment Fire Pre-Connect Lines described in the “Hose Load and Layout Examples” will provide adequate flow (115-140 G.P.M.) for indirect cooling and Direct Attack extinguishment of a fire within an enclosure up to this maximum size.  Fire areas exceeding this maximum size should be attacked using streams from the exterior to initiate a Structural Transitional Attack or a Blitz Attack.  The Indirect “Fog” Attack is a defensive option if the fire is in a decay phase and the building is unventilated and unoccupied.

Hoselines for the Indirect “Fog” Attack

The Indirect “Fog” Attack is a fire chief’s ultimate “economy of force” strategy.  One properly equipped, trained, and drilled engine company can complete extinguishment within minutes using a fraction of the hundreds of gallons of booster tank water carried on a typical fire service vehicle.

In addition to its suitability as a defensive measure for fighting initial decay phase fires in closed compartments, a chief, as a safety measure, may desire to use the Indirect “Fog” Attack in lieu of an offensive attack to extinguish fires inside unoccupied buildings, particularly those that are abandoned or consist of light-weight construction materials.  A chief may also find favor with the considerable fire containment and safety advantages gained by using indirect fog to extinguish cellar, crawlspace, attic, and cockloft fires before opening them up for entry or ventilation.  Therefore, the Iowa Formula is presented here.

The Iowa Formula calculates a “Rate of Flow” for three-dimensional water fog application to extinguish a compartment fire using an Indirect “Fog” Attack—a defensive strategy.  It was one of the earliest tactical formulas, developed through extensive experimentation, and was published in 1959 in Water for Fire Fighting (Rate-of-Flow Formula) by Keith Royer and Floyd W. Nelson.  The formula is very simple: volume of the enclosure in cubic feet, divided by 200, yields the “Rate of Flow” in G.P.M. to be applied into the compartment for one minute to achieve fire extinguishment.  More commonly, the volume of space is divided by 100 to calculate a “Rate of Flow” for a water fog application thirty seconds in duration.  Remember though, the compartment must be closed back up following water fog introduction and left undisturbed for at least one minute to complete fire extinction.  Thereafter, crews can enter to begin ventilation and other overhaul and salvage tasks.

An Indirect “Fog” Attack using a “Rate of Flow” calculated by the Iowa Formula, which is based on a mass of water applied over a specific period of time, should produce the desired effect within minutes.  Upon opening the compartment, spot fires may need to be extinguished, but the bulk of the fire should be out.  As part of their extension checks, crews need to search for accumulations of fire gases in compartments adjacent to, and even those not adjacent to, the one(s) involved in fire.

To eliminate the risk of a backdraft or other extreme fire behavior event, an Indirect “Fog” Attack can be used to quickly cool and extinguish the smoldering fire inside this ranch-style home.  For this 9,600-cubic-foot space, the Iowa Formula determines the flow rate to be just 96 G.P.M. to achieve knockdown with just thirty seconds of water fog application.  See how easy that is to remember: about 100 G.P.M. for each volume equal to that of a single floor in a ranch house.  You can undoubtedly visualize that the same flow could be used for a decay phase fire in a cellar of the same size.  Each of the Compartment Fire Pre-Connect Lines described in the “Hose Load and Layout Examples” will provide adequate flow for this three-dimensional fire attack.  Even the “Rubbish Line” will do the job, as long as a 100 P.S.I. fixed pressure nozzle is used.
A smoldering fire in a 4,800-cubic-foot attic (half the volume of the floor below due to the gable roof) requires just 48 G.P.M. of water fog for extinguishment using an Indirect “Fog” Fire Attack.  The Compartment Fire Pre-Connect Lines described in the “Hose Load and Layout Examples” are adequate for fires up to 11,500 cubic feet at 115 G.P.M. and 14,000 cubic feet at 140 G.P.M.  Applying water fog for one minute, instead of thirty seconds, doubles coverage capabilities of a given flow when using the Indirect “Fog” Attack.  If applied into the enclosure for one minute, water fog from any one of the Compartment Fire Pre-Connect Lines described in the “Hose Load and Layout Examples” could extinguish a cubic-foot area exceeding double that of one floor of a rancher.  Then too, you can reduce the coverage volume by reducing the application time.  For the attic, you could apply water fog at the rate of 115 G.P.M. for about 15 seconds to extinguish the fire with about 30 gallons of water.

The Bottom Line—Get Water onto a Ventilated Fire Fast

“Reset” cooling can save lives.  We asked this firefighter if a quick application of water can make that much of a difference.  “Indubitably,” he said, “but not just any knucklehead can do it.  Laaah-deeeeeee.  Hey fellas look, it’s woikin!”  He’s obviously not one to trivialize the momentous.  (Public Domain image from the 1936 Columbia Pictures short “Disorder in the Court”)

Hoselines for the “Fast Water” Structural Transitional Attack and the Blitz Attack (Including Direct Attack upon Main Body of Fire) 

The National Fire Academy (N.F.A.) Formula determines what is often called the “Needed Fire Flow” (N.F.F.) for the two-dimensional Direct Attack upon the seat of a fire in a building or compartmentalized area of building.  (Note: “Needed Fire Flow” is more properly the term for a similar, but more complicated and thorough, Insurance Services Office [I.S.O.] calculation.  Unlike the N.F.A. formula, the I.S.O. calculation is based upon an engineering and mathematical analysis of a building, and its intended use is primarily for municipal fire protection evaluation and planning.)  The N.F.A. Formula was developed using a composite set of statistics gathered from experiences fighting fires.  It is intended to be easily applied to field use.  The N.F.A. Formula divides the area (sq. ft.) involved in fire by three to determine the N.F.F. in G.P.M.  If the main body of fire involves space on more than one floor, then the space on each floor is added together to calculate the N.F.F.  Twenty-five percent is added to the calculation for each floor above the fire that is affected as an exposure (up to five) and for each side of the fire that has an exposure within thirty feet.  The N.F.F. figure is generally accurate for fires involving up to 50% of an affected space and for flows up to 1,000 G.P.M. in buildings that are not oversized (warehouses, etc.).  The N.F.F. calculation estimates the flow necessary to supply all fire streams that might be required to contain, extinguish, and overhaul a building fire, including those used for attack, backup, and safety/support.  The formula was developed from a study of the flows used by fire departments to apply a Direct Attack upon actual fires inside commercial buildings.

“Reset” cooling, when used to begin a “Fast Water” Structural Fire Transitional Attack or Blitz Attack, will reduce the N.F.F.  In addition, leading off with a master stream for thirty seconds or so to initiate the latter may improve the chances of rolling back a deep-seated or marginal working fire to significantly less than 50% involvement.

Remember that the N.F.F. was developed from statistics derived from experiences extinguishing structural fires that were being ventilated.  Keeping a building as closed-up as possible will reduce the heat release rate and should have the effect of reducing the N.F.F. requirements for a given fire.

Because it is not physics-based, the National Fire Academy Formula has no time limitation on water application for effectiveness.  At a very minimum, tactics using the Direct Attack application of water should be evaluated for progress at least every twenty—preferably ten— minutes.  Light-weight construction, inability to cool fire, insufficient water supply, or a deficiency of other resources may require abandonment of an offensive effort.  Sustained offensive operations using multiple 2 ½-inch hoselines to contain big fires in large buildings have been successful, but the buildings were of massive fire-resistive or fire-proof construction, thus allowing time for additional lines to be supplied, manned, and advanced to complete extinguishment.

Structural fires are extinguished using two-dimensional Direct Attack water application onto the burning fuel.  The N.F.F. is 250 G.P.M. for a fire involving 50% (600 sq. ft.) of the 1,200-square-foot area of this building.  That’s 200 G.P.M. for 50% involvement of the space equal to that of a single floor of a rancher, and 50 G.P.M. (an additional 25%) for controlling extension in the exposed floor above.  Rapid “Reset” cooling with a hand-held hoseline to initiate a “Fast Water” Structural Transitional Attack can turn back the growth of a working fire like this and keep it within the capabilities of any one or two pre-connect lines with flows from 115 to 185 G.P.M.  Additional lines need to be deployed to areas of exposure to check extension, in this case, at least one to the attic.  Even though the N.F.F. predicts the need for just 50 G.P.M. there, lines capable of the flow necessary to extinguish a fire in that space must be deployed.  Remember, fire gases may have accumulated in the attic enclosure, so a Compartment Fire Pre-Connect Line capable of three-dimensional cooling, as well as a suitable backup line, may be required there.
A service station converted into a tattoo parlor, beauty shop, tax office, or takeout restaurant like this custard stand has approximately 1,200 square feet of floor space, just like a single story of a ranch house.
Needed Fire Flow requirements for an area equal to the single floor of a ranch home.
Blitz Attack cooling using a master stream can provide a chance to knock a deep-seated or marginal working fire back to less than 50% involvement.  Using a hand-held hoseline to initiate “Fast Water” cooling before the advance is made to extinguish the main body of fire can improve the likelihood of success for the first-in crew by keeping involvement to significantly less than 50% and closer to 25%, possibly within the flow capabilities of just one line (which you still back up of course).
Process for a Blitz Attack.
The process for containing, cooling, and extinguishing a deep-seated or marginal working fire using a Blitz Attack.
Needed Fire Flow for an area of 2,500 square feet.
When fires occur in spaces approaching 2,500 square feet or more in area (exceding twice that of a single floor of a ranch home), firefighters must initiate their Direct Attack on the main body of fire with hoselines capable of flowing 210 G.P.M. and greater.  That means using 2-inch or 2 1/2-inch lines equipped with suitable combination nozzles or smooth bore nozzles with a 1-inch or bigger tip.  In spaces larger than 2,500 square feet, it is essential to “reset” the fire from the exterior to keep it closer to 25% involvement than to 50%, thus within the capabilities of one or two hand-held hoselines that are advanced for Direct Attack extinguishment.  Due to their increased size and flow, hoselines for fires in these bigger areas are more cumbersome to maneuver and advance.  You’ll need more personnel, both on the lines and in support roles.
A structural fire in a 2,400 square-foot convenience store necessitates the use of 2-inch or 2 1//2-inch hoselines capable of flowing 210 G.P.M. or more.  The N.F.F. for 25% involvement of the first floor in this building is 250 G.P.M., that’s 200 G.P.M. for the Direct Attack on the main body of fire, and 50 G.P.M. (25%) for controlling extension in the exposure (the attic).  Despite the formula only calling for a small flow for each exposure, it is sound practice to send a crew with at least one fully supplied line to each.
A restaurant, auto parts store, or other occupancy in a 3.600 square-foot space (three ranch-style homes) has a N.F.F. of 300 G.P.M. for 25% involvement.  To achieve quick Direct Attack extinguishment following “reset” cooling, a 2 1/2-inch line with a 1 1/8-inch tip flowing 270 G.P.M. may be necessary.  Note the heavy H.V.A.C. equipment on the wood truss roof.  If you’re not knocking the fire down immediately, and there is no life hazard, it’s probably a good idea to back out before the gusset plates let loose and those units come crashing down!  Believe me, they’ll build another store faster than you can pick the scabs out of your scalp.

Hand-held hoseline and master stream recommendations for Blitz Attack and “Fast Water” Structural Transitional Attack offensive tactics in spaces approximating those equal to one, two, three, or four ranch-style homes.  Leadoff line recommendations are for fires that have been “reset” to an involvement closer to 25% than 50% of the affected space.  All leadoff lines need to be backed up by at least one line capable of an equal or greater flow.  A “Fast Water” line can be used as a leadoff or backup line after “resetting” the fire.  Buildings containing a heavy loading of combustibles may require lines capable of greater flows than those listed.
A fire in an area of 4,800 square feet (four times the space of a single floor of a ranch-style home), assuming that there is one exposure above or on one side of the fire, will have a N.F.F. of 1,000 G.P.M. at 50% involvement.  This represents the maximum flow for which the National Fire Academy Formula claims any accuracy, and you can see why.  Quickly deploying the number of hand-held hoselines necessary to achieve the N.F.F. for any fire beyond 25% involvement in an area this size or larger is a task of great difficulty.  To buy time and reduce the heat release rate, “resetting” the fire by cooling it from the exterior using a large caliber stream is essential.  Fires approaching 50% involvement in areas exceeding this size will likely require cooling with multiple large caliber streams to contain the flames within the space.  Entry for a Direct Attack on the main body of fire may not be practicable.  If that space makes up a majority of the area of the building, a defensive strategy may be your only option.
A mixed-use structure measuring 24 x 200 feet with a continuous open retail, restaurant, or other commercial space on the first floor can present a real challenge to firefighters.  A fire involving just 25% of the 4,800 square-foot space requires 400 G.P.M. to effect a Direct Attack, meaning multiple 2-inch or 2 1/2-inch lines are necessary.  A fire in a building this size can become unpredictable from a N.F.F. standpoint.  At 50% involvement of the retail space, the N.F.F. becomes 1,400 G.P.M.: 800 G.P.M. for the main body of fire, and 200 G.P.M. for each of the floors above and for the exposure to the left.  Initiating a Blitz Attack to attempt to turn the fire back to significantly less than 50% involvement is the only offensive option.  After the cooling process, a chief must decide if the “reset” was significant enough to allow entry for a Direct Attack with the resources available, or if the master stream(s) should continue darkening the fire as part of a defensive-offensive (holding action) strategy.  To cover the evacuation of occupants from the fire building and adjacent structures, fire streams operated during a holding action may need to focus on the protection of egress routes until sufficient forces can be concentrated to permit a resumption of the offensive effort against the fire’s main body.
This mixed-use building with a footprint of 4,800 square feet is partitioned, giving firefighters a chance to contain a blaze in the first-floor commercial space to either the front half or rear half (space of two ranchers instead of four).  Fire involving 50% in either half could be assailed using a Blitz Attack to reduce the N.F.F. for the Direct Attack to below 400 G.P.M., and thus within the capabilities of two 2-inch or 2 1/2-inch lines flowing 210 G.P.M. or more.  The N.F.A. Formula calculates the need for 100 G.P.M. (25% of 400 G.P.M.) to check extension in each of the three exposures to such a fire: the front or rear, the floor above, and the building to the right.  Hence, the total N.F.F. for this example would be 700 G.P.M.  Early in the effort, you’ll want to make certain that lines are stretched to cover the unburned side of the partition and any stairways and corridors that are means of egress for the apartments above.
To select hand-held hoselines for a Direct Attack in a large building like this, you need to visualize any areas that are divided into apartments, stores, offices, classrooms, etc. as multiples of the rancher’s floor space.  This building contains many apartments the size of a rancher or smaller, so we can use the same N.F.F. for Direct Attack: 100 G.P.M. for 25% involvement, or 200 G.P.M. for 50% involvement of any one apartment.  But remember, we need to stretch many additional lines to protect corridors and stairwells, and to check extension on each floor above the fire, and on at least two, sometimes three sides of the burning space!  Ladder companies need to get set up and be ready to flow water fast, it may be their responsibility to provide “reset” cooling or to introduce water fog from the upwind side of a wind-driven fire.  To keep lines out of the stairwells where occupants may be evacuating, remember to use aerial apparatus to full advantage, as an elevated standpipe, when deploying hoselines to a fire area on upper floors.  Due to the size of the building, 1 3/4-inch lines deployed to fight a compartment fire or stretched for structural fire suppression need to be backed up by 2-inch, or better yet, 2 1/2-inch hoselines.  In buildings this large that aren’t compartmentalized, fires should be attacked with 2 1/2-inch hoselines.  Monitor progress carefully and don’t be afraid to get everyone out and contain the fire defensively if it begins to exceed your flow, supply, or personnel capabilities.

“…no fire can be controlled unless the cooling effects of the water application are greater than the generation of heat by the fire.  It just cannot be done.”

—Chief Edward P. McAniff, F.D.N.Y.

(“Strategic Concepts in Fire Fighting”—1974)

“…We had a large volume of fire on the upper floors.  Each floor was approximately an acre in size.  Several floors of fire would have been beyond the fire-extinguishing capability of the forces that we had on hand.  So we determined, very early on, that this was going to be strictly a rescue mission.  We were going to vacate the building, get everybody out, and then we were going to get out.”

—Deputy Chief Peter Hayden, F.D.N.Y.

(Testimony before the 9/11 Commission—May 18, 2004)

It’s Our Little Secret

…but there’s no need to keep it that way!

We hope you’ve found the information on this site engaging.  Our intention is to broaden our reader’s horizons on topics of fire science and fire service strategy and tactics while inspiring the free exchange of ideas among members of the firefighting community.  Now that you know a bunch of important things—particularly new things including facts, practices, and techniques to which your peers have not had any exposure —you’ll certainly want to share your enlightenment, but it might be best if you don’t overdo it.  Change is an ordeal, no matter its practicality or how it’s presented and implemented.  To lessen the shock, perhaps it’s wise to ease them into it, just a tiny bit at a time.  Then, when they finally ask, “where do you find all this stuff,” please consider giving our site a plug.  In the interim, you had better get out of here quick—before the wrong person sees you reading this.  But do stop back again soon.  And bring your friends along when they’re ready.

See you next time at the Riverside Firemen’s Retreat!

Even fires in the smallest of buildings can lead to tragedies.  Chief Bailey’s caption says it all.  Please think first and be safe out there, every time.  (Image by C. Bailey)