Thread: FNG methods of attack question
05-06-2006, 06:45 PM #1
FNG methods of attack question
I read this a couple times and I'm still confused. I was taught all three of these as interior attack methods based on fire conditions. The link to the entire article is at the end. You might have to subscribe.
METHODS OF ATTACK
How the first attack line is used will determine the outcome of the fire. The nozzle has the greatest impact on success or failure. The nozzle dictates the technique the nozzleman uses; if used improperly, it can be dangerous. The method will determine many factors of the fire condition and safety of the firefighters and occupants.
The three methods are the direct, indirect, and combination attack. We will discuss each of these. Of course, this is not an all-inclusive strategy and tactics text but only a small look at a small element of this big picture, the aggressive interior fire attack.
“The direct method of attack is simply applying water to the base of the burning material, at the flame/fuel interface, where the flammable vapors being distilled by heat from solid material ignite and burn.” 2
The direct method of attack causes little disruption of the heated combustion products. Reducing heat production by extinguishing the fire at its base stops the burning process at its source, in turn stopping the upward liberation of more heat, smoke, and gases. (2)
If the officer feels the overhead needs to be cooled because it is preventing the crew from moving in, a quick two-to-three-second dash with a straight stream will reduce the temperature without generating a massive amount of steam.3
The direct attack method is designed to extinguish the fire by applying water in a straight or solid stream to the base of the fire. This allows the greatest amount of penetration of the heat being produced. In our tests, the solid stream had a greater reach than a fog straight stream, allowing an attack from a distance that is safer. The stream will then strike the combustible material and reduce the temperature below the ignition level, thereby extinguishing the fire. With a solid stream of water passing through the heated gases, less steam is produced because of a larger mass of water. A wide fog pattern of water passing through the same gases will produce an enormous amount of steam because of the greater surface-to-mass ratio. This excessive steam could be pushed back on the attack crews and occupants, resulting in steam burns.
Since danger of a flashover is becoming more commonplace because of building construction methods and an increased use of plastics that have higher rates of heat release, it is imperative to recognize this potential. In environments of high heat, the solid stream can be directed into the ceiling area for a short period to lower the temperature. Since droplets of water produced by the solid stream’s hitting the ceiling are larger, they will absorb more heat without interrupting the thermal balance. If a wide fog pattern were to be introduced into this atmosphere, excess steam would be produced and possibly cause injury. Therefore, using a wide fog pattern could produce an extremely hazardous situation.
Although applying a solid stream to the ceiling is not attacking the burning material itself, it is viewed as a direct attack. Remember, smoke and gases are unburned combustibles that can ignite. But, as with a stream directed into other burning materials, you must limit the length of application to prevent excess steam. By directly applying water to the seat of the flame/fuel interface through the direct attack method, you don’t generate massive amounts of steam. In a direct attack, maintaining the thermal balance is imperative. Mixing the high heat from the upper level with the lower temperatures at the floor creates an imbalance in the room that is very dangerous. One final point about cooling the ceiling in high-heat conditions: Safety is paramount. Smoke is incomplete combustion. When present with enough heat and oxygen, smoke will ignite with terrible results.
“The indirect method of attack is not an interior fire attack operation.”4 “In addition to remote injection of the water fog, there are two other requirements for success when using the indirect method. First, the ceiling temperature within the fire compartment must be at least 1,000° F, to ensure readily and efficient conversion of the fog spray to steam. When a fire is in the first or second phase of development, the direct attack with timely and adequate ventilation is preferred. Second, the fire compartment (building) must be well sealed to prevent premature leakage of valuable steam to the outside. A well-ventilated fire building on the fire department’s arrival warrants a direct attack, since the indirect method is only effective if the fire building remains sealed with doors and windows intact.” (4)
“Nowhere in his writings did Chief Layman present scientific arguments that advocate spraying water over the firefighters’ heads in a fire situation to create steam-bath conditions. On the contrary, he said firefighters would be burned if they were unfortunate enough to find themselves enveloped in a hurricane of water converting to steam.” (2, 84)
“Like the indirect method of attack, the combination attack was originally designed primarily for exterior application of water.” (4, 68)
“The objective of the combination attack is to ‘roll’ the stream around the perimeter of the room, cooling the walls, ceiling, and floor with the outer edge of the stream while the inner portion of the stream cools the hot gases being produced by the fire. Striking the heated ceiling, walls, and fuel material produces the maximum amount of steam within the shortest period of time.” (4, 70)
“Insofar as the writings of Keith Royer and the late Floyd Nelson, of Iowa State University, are concerned, there is no mention of the impact of steam on trapped occupants. In Fire Stream Management Handbook, Fornell writes in reference to the articles and films of Royer and Nelson: ‘In viewing the films and reading the results of their research, it must be noted that their tactics advocated application of water from outside the fire building. Though they did discuss interior application, the first priority in the Iowa method was to knock down visible fire before making entry. Royer says their testing did not address the problem of fire spread caused by applying streams from outside the building. The subject of life safety or the effects of steam on trapped victims was never addressed in three films.’” (4, 74)
The indirect and combination attacks are not designed for an interior aggressive attack. These techniques have been misused because of a lack of understanding on the part of individuals, departments, and training centers. The original developers of these two attack methods never intended them to be used as interior operations, contrary to what we have been taught regarding the aggressive interior attack. The massive amounts of steam produced from the indirect and combination methods of attack pose a danger for the firefighters and trapped occupants. Also, there is potential for fire spread: The power of the fog stream can push the fire throughout the structure.
Last edited by DonSmithnotTMD; 05-06-2006 at 06:46 PM. Reason: grammar correctionI am a highly trained professional and can find my :: expletive deleted:: with either hand in various light conditions.
05-06-2006, 07:17 PM #2
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- Mar 2006
What are you confused about, exactly?
05-06-2006, 07:27 PM #3
It sounds like he's saying only direct attack is for interior attack and the other methods aren't. I'm probably missing something because I read poorly on computer screens.I am a highly trained professional and can find my :: expletive deleted:: with either hand in various light conditions.
05-08-2006, 09:42 AM #4
you need to understand two things. in an interior attack, you aren't in the fire room. in a direct attack, you are.
for example, lets say you have one room going, with confirmed no one in the room. it hasn't been vented yet. you begin to make entry, and encounter high heat. so using a fog nozzle set to a narrow fog, you give a couple squirts into the room from the doorway. what happens? that's right, the water converts to steam, and increases in size at a rate of 1700:1. it also fills the room with steam. you might also bring all the hot stuff down to the floor. but that's ok, because while the temp might skyrocket, it's a wet heat from the steam.
now if you are inside, what happens to you? you are going to take a trip to the burn unit. you'll be steamed like a lobster.
but what if your outside the door, and after you pulsed the nozzle, you closed the door? well, the steam is all in the inside of the room, and that steam is helping to put out the fire. and your protected by the door.
now your exterior crew vents the room, and the steam goes out the window. if the room was already vented, the water wouldn't be able to change to steam and fill the entire room and put out the fire.
now, for a direct attact, you are in the fire room. you don't want steam. you want to take your nozzle, and put out the fire. steam is bad, as it will turn you into a lobster. straight/solid stream, at the base of the fire, with the room already vented.
Does that help/make sense?If my basic HazMat training has taught me nothing else, it's that if you see a glowing green monkey running away from something, follow that monkey!
05-13-2006, 11:25 PM #5
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- Oct 2005
There has been a strong emphasis over the last 10-12 years or so to advocate (especially in Fire Engineering) only smoothbore / straight stream operations by "interior" crews.
It's the most generally useful tactic; it's also the safest to teach.
It's especially important if you have a department that conducts Vent-Enter-Search or search ahead of the line tactics.
Some of the conditions that existed when Lloyd Layman's tactics where first adopted have changed dramatically. Back then, a rural fire department was lucky to have a 500 gallon booster tank, and even after establishing water supply via a shuttle of small tanks or a lay of small diameter lines like 2.5" or 3", you where doing very good to have 150gpm sustained flows. Conservation of water was critically important, and you had even more extended notification and response times in the days before 911, radio pagers, and reliable / powerful Diesel engines.
In my town, we now have single trucks that carry more water then all the fire apparatus combined from 3 stations in town carried forty years ago. The rest of the trucks carry more water, and they can arrive at a scene to reinforce a fire attack faster thanks to better notification, better trucks, better roads, etc.
So water conservation benefits of techniques like Layman's are no longer nearly as critical.
"Fogging" a room can be done be a crew inside the building -- but exterior to the fire compartment. There's few situations today that I can see that this would be a preferred tactic. I do believe indirect and combination tactics should still be taught and understood, recognizing they're increasingly for specialized situations.
While there where certainly some people and areas that corrupted the principles of fog-based firefighting...the core set of principles are still valid. What has happened is many other factors have changed around them swinging the pedelum back to straight stream & smooth bore tactics for many areas that previously relied on fog tactics.
05-29-2006, 11:19 PM #6
Just got back.
Thanks I learned a bit. In my FF1 class we practiced all those techniques as interior methods with us in the room -- all straight stream.I am a highly trained professional and can find my :: expletive deleted:: with either hand in various light conditions.
06-24-2006, 07:08 PM #7
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- Jun 2006
07-24-2006, 04:00 AM #8
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- Jul 2006
As mentioned before.....if you are in the room, or "compartment", use a straight or solid stream. Hit the base of the fire if you see it, hit the ceiling and floor if you can't determine where the base is.
You can use a narrow fog, but only if the room is ventilated beyond the stream. This requires a coordinated effort with different companies, which comes down to having experienced command.....I have rarely seen this in effect at a fire.
If you use a fog or wide fog without ventilation beyond the stream, you risk pulling heat, smoke, and fire over your head and back onto you, as well as the risk of large amounts of steam being produced.
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