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Big Box Fire Attack

Posted by Shan Raffel
Shan Raffel
“Shan has pioneered and championed a global paradigm shift in fire fighting tech
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on Monday, 11 March 2013
in Industry Insights

After looking at the tactics used at a number of big box fires in my own city (Brisbane, Australia) in the last decade, I believe that once the accumulated smoke layer ignites the whole structure is going to be lost. Further, I believe that unless the seat of fire can be seen and quickly hit that we need to shift focus to preventing the accumulating un-burnt fuel from igniting in the over pressure.

The technique I have been promoting to cool those gases in the ceiling. I am NOT talking water-fog or pulses. We need big lines (minimum 64 mm) with a flow rate of at least 475 LPM. Must be set to a jet or it will not reach the ceiling. The objective is to rake the jet across the ceiling. The jet breaks up on striking the surface which cools the gases and the surfaces where they are hottest. Effectively we are trying to separate the gases above the fire from the un-burnt fuel in the remainder of the structure.

This will not put the fire out. It only buys time to locate and confine the fire. Attack needs to be initiated with at least 64 mm lines with good flow and a hard hitting jet to give maximum projection and striking force.

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“Shan has pioneered and championed a global paradigm shift in fire fighting techniques that are now accepted as standard practice. His expertise in this area is what drives QLFA seamlessly through the industry”

Comments

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Juan Carlos Campaña López Monday, 11 March 2013

Good coment my teacher... as ever.... and as I learned from your book....

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Franck Gaviot-Blanc Wednesday, 19 June 2013

Hello Shan !
Thanks for share this interesting point of view. In a large compartment, John teaches the "long puls" technique (approx 20° of spray angle at 100 until 250 lpm) with a duration puls between 4 or 5 ... or more seconds, and why not practice a "big sweep" as in sweden, for cooling smoke and hot gaz. Do you think this kind of techniques doesn't work well enough ?

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Franck Gaviot-Blanc Wednesday, 19 June 2013

Hello Shan !
Thanks for share this interesting point of view. In a large compartment, John teaches the "long puls" technique (approx 20° of spray angle at 100 until 250 lpm) with a duration puls between 4 or 5 ... or more seconds, and why not practice a "big sweep" as in sweden, for cooling smoke and hot gaz. Do you think this kind of techniques doesn't work well enough ?

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Shan Raffel
Shan Raffel
“Shan has pioneered and championed a global paradigm shift in fire fighting tech
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Shan Raffel Sunday, 25 August 2013

Hi Franck!
I refer to short pulses of 1 – 2 seconds being well suited to cooling gases in small compartments.
Medium pulses 3 – 4 seconds for cooling gases in medium sized compartments and for attacking flames.
Long pulses of 5 or more seconds are good for cooling gases in larger spaces or attacking and pushing back flame. When you need long pulses you generally need to think about increasing the water flow to at least 225 lpm.
I have found from experience at real fires that a big sweep can be quite effective in larger volumes. I am less inclined to sweep in small compartments as it can disrupt the thermal balance a bit. Having said that, the balance is quickly restored so it is not a major issue.
I don’t like to quote a cone or nozzle angle because it depends on the room geometry, but I think you may need to get as narrow as 20 degrees or even a straight jet with maximum flow rate in very large spaces. The further the droplets have to reach the narrower the cone must be. So if the area is large I tell the student that they need to try to get droplets into the farthest corner. This could need a narrow cone angle and a low branch angle (some of the droplets may be projected below the neutral plane and some may hit the ceiling if it is not so high). If you are trying to reach a high ceiling the cone angle may have to be quite narrow and the branch angle relatively high.

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Shan Raffel Saturday, 24 August 2013

Hi Franck!
The long pulse is necessary in buildings that have a relatively larger volume due to a large floor area or a high ceiling. I don’t like to quote an angle for the cone because it depends on the geometry of the compartment. I teach that the cone angle and horizontal angle needs to be sufficient to reach the upper half of the back corner or ceiling.
As the compartment become larger it becomes necessary to narrow the cone angle to reach the most distant corners and/or the ceiling. I actually like to talk about short pulsations (1 to 2 seconds) for gas cooling. Medium pulsations (3 to 4 seconds) for cooling larger volumes of smoke or small volumes of flames. Long pulses (5 seconds and above) very large volumes of smoke or large volumes of flame. I base my opinions on my experience during a lot of acquired structure burns and practical experience in my role as an operational Station Officer. My experience is that sweeping can be very effective in situations where long pulsations are necessary. As we move to medium pulsations we must be more careful with sweeping as if it is not skilfully applied there may be a disruption of he thermal balance. Usually any disruption in this case does not last very long. When we get to context in which short short pulsation are to be used, I don’t like to use a sweeping movement. I have done quite a bit of practice in small scale props and I find the sweeping is effective, that just moving the branch to different angle works better. Personally I prefer to use gas cooling in preference to indirect extinguishing unless there is no other option. Indirect attack generally works very well from outside as long as the compartment is closed up or, the duration is just long enough to black out the compartment.
I prefer to hold the bumper with my left hand and the shut off handle with my right hand (with the hose line in my right-hand side). By holding the bumper stationary, and using a rotational movement with the shut off handle, it is possible to vary both the flow, opening duration and cone width. This is the most effective nozzle technique, but it should only be taught in a context where ongoing nozzle practice is likely to occur. Otherwise just stick to the basic technique where one hand is always on the piston grip and the other hand alternates between the shut off and bumper. Less effective but more likely to be successful with unskilled nozzle operators. For the average user we must keep it simple!
Franck, we need people like you to use science to keep the practical application honest!

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Ed Hartin Sunday, 08 June 2014

Another consideration in large compartments such as a big box store is to focus on quick application of water to the seat of the fire. This can often be best accomplished by attacking from the burned side or an access point close to the fire (rather than traveling a considerable distance under the hot upper layer). This does not diminish the need to cool the upper layer, but provides an option with considerably less risk than the more traditional attack from the unburned side which in this case may require considerable travel distance under the hot upper layer.

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