Vehicle fires

[TELBOY]

Hi, can anyone help with this possibly simple question. What is the best method of extinguishing a vehicle fire? I am aware that in motor sports we use ABC Powder and AFFF, so why do fire brigades use only water?

[callansdad]

probably cause its cheaper and theres lots of it!  why waste taxpayers money on powder when waters free!

[AnthonyB]

Halon used to be an agent of choice for vehicles initial attack where capacity was limited such as in cab extinguishers or automatic systems.

The fire service use water as they have an extremely large supply, they have full PPE, can stay a safe distance at first & can take their time - they are just putting ot a fire in an empty car most of the time. They will use the spray & fog settings on their branches as well as jet. also when well alight, the majority of a car falls into Class A, where water is the best.
However tactics will alter dependant on the circumstances & crews will use foam or the appliances DP extinguishers if indicated.

In motorsport you are facing a life safety (occupant) risk where time is of the essence, have only limited amounts of extinguishing media & are generally responding to a fire caused by crash or catastrophic engine failure where there is a greater risk of a running Class B fire from fuel leaks, whereas a lot of street car fires are arson. In this circumstance you need the rapid knockdown & high mass for mass capability of DP followed by the post extinguishment security of foam blanket.

If you have limited media such as portables or trolley/skid mount, especially with a life safety risk then a DP knockdown (ideally by high performance BC agents such as Monnex or Purple K, but cost is an issue so a high MAP content ABC is a good second best) first is best, AFFF being good for security (unless a PSV where it is mandatory instead of powder as powder isn't good to discharge in a bus full of people).

If time, supplies & life safety are less of a worry then you can throw a lakefull of water at it - even if there is a fuelspill, small shallow spills can be taken out with water fog - but I'd have the AFFf tank & inline inductor ready just in case...

[messy]

Anthony

I agree with the sporting life risk v FB property risk element to your reply, but it still concerns me that many FRS have standard operating procedures which state that water (hosereel or jets) should be standing by at RTAs with persons trapped!!!!.

I have always ignored such a procedure and have insisted on DP for instant cover with foam (hr) jets standing by for person trapped incidents. Even after explaining the rationale behind my approach to argumentative crews (& officers), some still resist!

[fireftrm]

I would resist DP at any incident with persons trapped. The powder will get everywhere causing respiratory irritation and panic. It will make seriously affect visibility and persons trapped may well fear that there is a large fire due to the 'smoke' as they are likley to see it (assuming they aren't coughing their guts up and blinded.

We no longer carry DP due it compacting and accidents with in-cab extinguishers and the serious potential consequences that were, luckily, avoided. The DoT state that any PCV extinguisher must be water based for just the that same safety reason. We use HRs and AFFF extinguishers. I have confidence that a hosereel can deal with a sudden fire as it is already there and has firefighters standing ready to use it; together with less danger than covering the area with a blanket of choking/blinding powder. In addition it can cope with windy conditions.

Messy I remain argumentativley resistant to your idea and would promote the entirley opposite viewpoint at every opportunity. Perhaps you should have examined why many FRS (if not all) have SOPs where the HR is the fire protection and not DP. After all SOPs are derived from risk assessments and experience...........

[fireftrm]

PS note that the use of DP exts in motor sport, by marshalls, is directly connected to the extinguishing capability of these versus other extinguishers. Drivers will be expecting these and have PPE themselves. If the marshalls had a 1800l water tank and a high pressure hosereel in their hands would this still apply?.............. they haven't, we have and our drivers are not experienced in the safety measures nor wear PPE.

[Goodsparks]

last year at fire expo one brigade demonstrated the use of a 1k ABC powder discharged through a water spray from a standard hose reel, onto a large (3 metre diameter) fuel spill fire. The combined extinguishant put out the fire in seconds, with no flare-up and probably only used half of the DP extinguisher.

The water depressed the airbourne DP particles and prevented any clouding.
Would this combined approach not provide a suitable solution ?

[fireftrm]

Works well on jet engines too, but does mean carrying DP exts. As  for only using half you cannot only use half an extinguisher any used and it is empty as far as we are concerned.

[Matt Akers]

I can see the point behind be hind DP used at a race track (very mobile and dose the job). DP has many disadvantages (visibility breathing ect) I think I could handle a race diver coughing and spluttering if the fire was put out and he/she got out, like some one said they have PPE on themselves.
We went to an RTA recently with 1 person trapped and the car court fire, hose reel did the job very well and did not cover the causality or us in powder. I think we just have to accepted that on a race track DP is very mobile and puts the fire out very quickly, in an RTA environment were the causality has no protective clothing and we have a clean way of putting the fir out then we will always use hose reels, unless the car has a running fuel fir the DP it the best option.

[messy]

My views are based on 28 years of experience of chasing countless car fires for several minutes with hosereels, before any progress is made. Especially if unleaded fuel is involved.

With persons trapped, you aint got those minutes - it's got to be out pretty damn quick and DP (with foam h/r backup) does the job. I accept it will not be pleasant for the trapped punter to inhale any quantity of DP, but neither is is comfortable sitting (trapped) within a 1MW car fire!

8/10 trapped persons (when questioned) said that they preferred speed over comfort when escaping a car fire*


*Source: Ministry of Stating the Bleeding Obvious Survey 2005

[AnthonyB]

The whole point of DP is speed and performance - with limited resources weight for weight it is the only thing that will do the job quickly. Yes it obscures vision - so does smoke, yes it is unpleasant to inhale, but it isn't toxic. Critically it has no flashback resistance or cooling effect, but thats why once the initial danger from the fire is over you follow up with an AFFF blanket.

A critical isssue is training  -  with DP you've got to put out the fire in one go or it flashes back & if you're extinguisher runs out (5-15 seconds tops) you are stuffed - watch the footage of the Palletti fire at the '82 canadian GP for poor use of extinguishers.

Since the demise of halon, DP has taken over as the first choice for vehicle extinguishers as the most effective.

Under the construction & use regs for buses you can only use water or foam now halon has gone, but thats nothing to do with engine fires - its in case of fires in the actual interior of the vehicle (e.g. seats) where a powder discharge would indeed be unwise.

Each agent has it's place and application (& Indeed in many cases multiple agents should be used) and is shortsighted to dismiss one across the board without a god reason

[fireftrm]

Sorry I'm with Matt. Hosereel always DP never. The point being that the fire starts after you arrive, you have a hosereel in your hand. The car fires that you have 'chased' for several minutes would have been well established ones, with tyres and under-bonnet fires being the parts that were difficult to extinguish. Both would require water, or foam. I very much doubt (though await with trepidation the response) that these fires have been at RTCs. Only in American TV/Films do cars busrt into flames in accidents (though if they did the fires would be very well established by the time we arrive).

99.9999/100 of entrapped occupants said they had a fear of fire and yet it never happened (source the Ministry of Accurate Statistics - every year since records began) PS the figures have recently been amended due to Matt's report of 1 fire at an RTC.

4/10 people thought the 'powder' from an exploding airbag was smoke and therefore the vehicle was on fire (source Fire Service experience)

99.9999999/100 car fires around the country are extinguished by hosereels, or occasionally foam (for those who see unleaded as a major problem).

100/100 RTCs result in trapped occupants and no fire (my experience and that od all my colleagues)

100/100 of alll RTCs we respond to are not attended within any less than 5 minutes, by which time any fire that started at the time of the RTC would have fully engulfed the vehicles and any trapped occupants. Indeed over 90/100 of such RTCs have an attendance time in excess of 10 minutes. (source the  General Technical Office of Real World Regulation - GetOffReal!)

I therefore dismiss DP as a substitute for a hosereel and have given many good reasons.

PS high pressure hosereels are actually quite good on running fuel fires and work just as well when it is windy, quite a common occurence outdoors on live roads especially in rural areas where there are no buildings for shelter. Most of our RTCs occur on high-speed rural roads.