The Riverside Firemen’s Retreat
STRATEGY AND TACTICS FOR FIGHTING TODAY’S BUILDING FIRES
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.
New FIRE ATTACK STRATEGY Stuff Added
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”
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.
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?
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—Backup/Redundancy When Using Hydrants
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.
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.
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.
DEFENSIVE FIRE ATTACK 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.
DEFENSIVE FIRE ATTACK STRATEGY…again
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.
DEFENSIVE-OFFENSIVE FIRE ATTACK STRATEGY
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.
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!
OFFENSIVE-DEFENSIVE FIRE ATTACK STRATEGY
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.
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!
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.
FIRE ATTACK STRATEGY “COACH’S CARD”
View by clicking the image below…
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
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.
Structural Fire Offensive Fire Attack Tactics
—”Fast Water” Structural Transitional Attack and Blitz 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”.
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.)
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
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.
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.
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.
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.)
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…
- 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.
- 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.
- 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.
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
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.
Be current on the latest in structural firefighting and fire behavior innovations by checking these web resources regularly…
- The Underwriter’s Laboratories (UL) Fire Safety Research Institute (F.S.R.I.) maintains a comprehensive website with firefighter training materials, reports detailing fire dynamics experiments, and much more. The work Stephen Kerber and his associates are doing is a “must follow”.
- The National Institute of Standards and Technology (N.I.S.T.) Engineering Laboratory’s Fire Research Division posts up-to-date information on topics including fire dynamics, firefighter safety, and firefighting tactics. You’ve got to check out the research Dan Madrzykowski (now at F.S.R.I.) and his peers have done.
- The modernfirebehavior.com website, jointly sponsored by the UL Firefighter Safety Research Institute and FirefighterCloseCalls.com, contains training materials for the S.L.I.C.E.-R.S. tactical guideline and other topics. Frequent posts from a variety of sources keep you in the loop. Check them out at least weekly for something new.
- The International Society of Fire Service Instructors (I.S.F.S.I.) website provides training materials for S.L.I.C.E.-R.S., “Fast Water” Structural Transitional Attack, and fire behavior.
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.
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.
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.
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
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.
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.
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.
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.
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)
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.
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…
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.
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.
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.
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.
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.
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!
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 darn 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.
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.)
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.
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.
- Evacuation profile of exposed buildings.
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.
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…
YOUR GENERAL PLAN OF ATTACK SHOULD BE…
- The initial line placement heads off the fire spread.
- Then, the sprinkler system should be supplied. (fire building and exposures)
- Place additional lines so as to surround the entire fire area.
- Back up those hose lines in heavily involved areas or where men may be in danger.
- Fill in the supply to elevating platforms, ladder pipes, standpipe and sprinkler connections.
- Assign a spark and brand patrol if needed.
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…
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.
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.
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).
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.
FIRE HYDRANT COLOR CODES
Available flow with a 20 P.S.I. residual pressure
CLASS AA 1,500 G.P.M or greater LIGHT BLUE
CLASS A 1,000 to 1,499 G.P.M. GREEN
CLASS B 500-999 G.P.M. ORANGE
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.
—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.)?
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.
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 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 BASIC NURSE TANKER/TENDER CONFIGURATION
A NURSE TANKER/TENDER CONFIGURATION FOR LARGER FIRES
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.
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.
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.
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.
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 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?
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:
VOLUME OF STRUCTURE
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…
OCCUPANCY HAZARD CLASSIFICATION NUMBER (O.H.C.N.)
- 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…
CONSTRUCTION CLASSIFICATION NUMBER (C.C.N.)
- 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.
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)
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)
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
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
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)
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)
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 as new construction, particularly where land is expensive. This dwelling, 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%, residential fire sprinkler systems are seldom installed 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”—must apply, don’t you think?
A 54′ x 32′ Bank Barn
with Exposure Hazard
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
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.
WHAT ABOUT FARM SILOS?
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.
Commercial Pork or Poultry Barn (8,325 square feet)
with Exposure Hazard
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.
NIGHTMARE ON ENTERPRISE STREET
A Warehouse/Freight Terminal (1,000,000 square feet)
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!
—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.
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.
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.
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.
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.
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.
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.
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).
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.
—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.
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.
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.
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.
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.
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.
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.
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.
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.
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”.
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.
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.
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.
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.
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…
- The initial line placement heads off the fire spread.
- Then, the sprinkler system should be supplied. (fire building and exposures)
- Place additional lines so as to surround the entire fire area.
- Back up those hose lines in heavily involved areas or where men may be in danger.
- Fill in the supply to elevating platforms, ladder pipes, standpipe and sprinkler connections.
- 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.
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.
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.
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.
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.
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.
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.
—Response Assignments in Rural Districts
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
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?
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.
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.
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.
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…
FIREFIGHTER’S PRE-CONNECTED HOSELINE REFERENCE AND PLANNER
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.
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.
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.
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.
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.
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”.
SAMPLE HOSE AND NOZZLE LAYOUT
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.
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.
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 Helpful Trick for Making Flow Estimates
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.
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.
The Bottom Line—Get Water onto a Ventilated Fire Fast
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.
“…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!