Thread: Smoldering Fire Tactics
09-21-2002, 12:16 AM #1
- Join Date
- May 2002
- Starkville, MS
Smoldering Fire Tactics
What tactics would you use on a smoldering fire such as the one that claimed the lives of the 5 Paris firefighters?
Despite initial reports of gas leaks leading to the explosions, later reports indicated that a backdraft occurred when the firefighters entered a small room where a mattress had been smoldering.
Two tactics come to mind:
1. Vertical ventilation prior to entry to the room. This would require that vertical access was feasible, i.e. that they were on the top floor of the structure. Reports indicated that they were on the 6th floor, but I don't know how many floors there were above the fire floor.
2. Pulsing fog techniques to cool the gas layers. How would you accomplish the cooling without letting in too much O2? Open the door, pulse vigorously, close the door, repeat?
Both tactics would require that you quickly identify the fact that you have a smoldering fire - observing smoke patterns and/or having a TIC prior to entry.
09-21-2002, 03:43 AM #2
This post is highly topical Brian and I would like to add my views as part of the debate. Firstly, this is a 'bread & butter' fire - its the type of incident that firefighters face every day in many cities and towns across the world - a one room fire that is contained, having developed to a stage of remission.
In the Paris incident I understand there was another floor above them and vertical venting would be impractical. Their approach to the room was along a narrow corridor but I am uncertain of smoke status or conditions at this time in that area.
The key areas for debate are -
1. The approach.
2. The door entry.
3. Venting actions at any stage of ops.
4. The use of water - straight/fog?
5. Moving in on the fire.
6. Back-up and support ops.
Imagine this situation - you are in SCBA with your partner, traversing the corridor, you locate the room involved and 'force' entry and within seconds the air around you hits 2000 deg!!! How can we deal with this?
The answer is -
1. Fire gas cooling and 'inertion' on the approach route directing brief 'pulses' of water into the overhead in front of you.
2. A slow and controlled door entry procedure, ensuring the door is opened slowly and only partially (2-3") at first (where possible). You MAY be able to place a nozzle into the opening and apply 2-3 short bursts of water-fog into the room, paying close attention to air flows and smoke patterns as the door is breached. Where air or smoke is drawn back in through the lower levels of the opening; or where pulsing smoke patterns are seen to shift back and forth at the doorway; or where smoke is seen to create a 'twister' about the size of a soccer ball as it heads back into the room; or where flames are briefly noted as 'detached' and apparently floating in air - CLOSE THE DOOR IMMEDIATELY and ISOLATE the fire. This all happens within a few brief seconds - there is not much time to think! If you did manage to inject some 'fog' into the room, close the door and allow it to do some work, possibly attempting this again prior to entry.
3. Where it has become necessary to 'isolate' the fire (or perhaps even at the outset of ops) then an exterior venting action is called for - either from a ladder or perhaps using hooks from adjacent windows or as a last resort, from above, to clear the window of glass.
Great emphasis must be placed on an 'awareness' of how fire gases may form (may be invisible); transport (along corridors, into stairshafts and voids or even adjacent rooms on upper floors, away from the fire); and ignite (in many ways). Once we are AWARE of the hazards we can form a plan to deal with them. I am not suggesting EVERY 'flashover/backdraft/smoke explosion' can be prevented - but many of them can if the approach is correct and the assessment of risk is effectively applied.
Last edited by PaulGRIMWOOD; 09-21-2002 at 03:48 AM.
09-21-2002, 07:15 AM #3
- Join Date
- May 2000
- Wheaton IL
While I haven't read everything about the guys in France, what you are describing sounds like the same old problems, lack of adequate ventilation. The importance of good ventilation can't be over emphasized. Horizontal or vertical, whatever is appropriate, but open the building up. If the products of combustion have somewhere to go then Backdraft and Falshover is greatly reduced.
I saw a demonstration once that was quite educational. Two small rooms were built one without windows just the small doorway so you can see and one was built with a normal sized door, and a few medium sized openings (windows). Equal amounts of class a combustables were placed in the room and fires lit. At first the fires were about equal but then the closed room took off fast and flashed. The other room continued to grow and eventually became fully developed, but it was nowhere near as fast. The only difference was the ventilation.
You should vent as if you were going in without airpacks.
09-21-2002, 08:43 AM #4
ADSN - I agree that tactical ventilation is the most important option in this scenario but there are other considerations also.
A room fire will progress to a 'fully developed' stage providing there are adequate amounts of fuel, heat and oxygen. If there are several 'window' openings (as in your example) then as long as sufficient fuel is available the fire will progress. However, there are many other factors involved that affect such development. The format of the fuel is important - ie; the same amount of wood will influence burning rate differently, depending on how it is accommodated. For example, wood cribs will burn differently to panel wood wall linings. Also, the position of items within a room will also influence the speed of development - corner items that are tall will usually enable a faster development of the fire than low centrally based items.
If, as in your example, the window openings are plentiful then the fire may have more air/O2 than is required and will burn in a 'fuel-controlled' environment. This type of fire does not normally present a great hazard to firefighters in terms of rapid fire progress. However, most rooms only have one or two openings and a developing fire within will struggle to obtain sufficient oxygen to advance steadily. Such a fire will burn in a 'ventilation-controlled' environment and this is dangerous and may offer unpredicatble conditions to firefighters.
Your examples offer exactly these two scenarios - one fire possibly in a fuel-controlled state with the other limited by openings in a ventilation-controlled state. The Paris fire was almost certainly in this (second) under-ventilated situation when they forced entry.
When a fire is vented from the exterior in this ventilation-controlled situation various things can happen - for example;
1. Most of the dangerous fire gases in the overhead will leave the room via the venting point providing the opening is made at a high level (upper portions of the window).
2. If this does not happen then air-in-flow at the venting point may create a dangerous air/gas mix that could ignite 'explosively'.
3. A flashover could result, from this venting action, as 'thermal runaway' occurs - where more energy (heat) is released in the room than can be lost through the opening.
4. If room flashover does occur the fire will require even more air to contnue burning at this rate. The window alone may not offer adequate supplies of air and an open doorway (corridor) would serve well to provide this additional airflow, creating potentially explosive conditions at the entry point and in the corridor itself leading to corridor flashover.
Having said all that - venting must still remain as the ideal option prior to entry, although fire isolation; venting of approach routes; gas cooling and 'inertion' must remain as considerations.
09-22-2002, 04:15 PM #5
- Join Date
- May 2002
- Starkville, MS
Paul - Interesting insight on all of the observations possible when just barely opening the door. It definitely highlights the importance of being able to 'read the smoke/fire.' How well would inerting the gases in the approach corridor, whether with pulsed fog or through ventilation, protect a team in the event of a backdraft after the fire room is opened? It would certainly reduce the chance of a secondary explosion in the corridor.
drkblram - Perhaps your shipboard training addressed the above question. In your training, did you get guidelines on how many open-the-door/pulse/close-the-door cycles are typically necessary to prevent smoke explosion? You mentioned high velocity fog, what is the typical Navy firefighting nozzle/hose/pressure?
09-22-2002, 07:16 PM #6
- Join Date
- May 2002
- Starkville, MS
Thanks for the additional info. I didn't realize that the compartment doors open outward - could be ugly if there's an explosion behind the door!
Do you have control of the fog angle on those nozzles?
09-23-2002, 04:04 AM #7
'inertion' or 'venting' of the fire gases on the approach route is a necessary action. If the gases can't be vented then an 'inertion' should be attempted by suspending fine water droplets (hang time 3-4 seconds) in the overhead. This means continuous 'pulsing'.........
If a backdraft occurred in the room serving the corridor then the expanding gases will blow-out of the room and into the corridor as they ignite - no amount of corridor venting or inertion will stop this! However, it may be that there is no gas ignition in the room itself but the actual ignition occurs in the corridor/hallway, just outside the room, as the door is opened. If the gases have been vented from the corridor prior to opening the door there will not be an ignition - if the gases have been 'pulsed' (inerted) then any ignition in the corridoe MAY be quenched.
Interesting take on the ship tactics - but remember, venting is not an option here.
09-23-2002, 05:58 PM #8
My apologies drkblram - you offer sound advice and I agree with your approaches. Just wanted to make it clear that Navy firefighters rarely have the opportunity to utilise any tactical venting action to relieve conditions - no windows - as there normally are in structural settings. Your tactics are sound for ship firefighting. If you had the opportunity to cross-ventilate a smouldering room prior to entry via an exterior window would you do so?
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