Posted By Nigel
Although I know official guidance states extinguishers should be located on escape routes, at exits from rooms or floors & at FINAL EXITS I've always been puzzled ... why at final exits? Surely once you've reached the final exit you're going to be more interested in going through it than picking up an extinguisher ... and to do what with it in any case? If they're intended to aid your escape through the final exit then having them located right next to it (that seems to be standard practice) probably means you'd have to be standing in the fire that's blocking your escape in order to reach them. I don't get it.

Can anyone please enlighten me?

Posted By D H
It also gives you something to fight fire with if your escape is hindered by fire- also useful for breaking glass etc to aid escape.

Dave

Posted By FAH
Hi Nigel

This is an issue that has been revisited so many times on this forum.

In the UK there are NO rules as to where FEs must be placed; so, those doing the FRA are required to identify exactly where the FEs should be placed. Most of those who decide to place them at only exits are, in my opinion, not thinking about the real issues at all!

Regardless of where you are in the world; with regard to selection & placing of FEs, the first criteria MUST be to identify any area [using the FRA] within the premises that could be difficult to escape from if a fire occurred between that place and the exit [normally termed "dead-end" conditions]- the most appropriate FE should then selected and placed within that dead-end to facilitate the escape of any persons who may be there when a fire occurs.

The nonsense that is frequently given about the FE being at the exit to facilitate going back into the fire to attack it is patently a direct contradiction of the UK workplace fire safety legislation that requires all those affected to leave without delay AND for the premises controller to ensure that no-one returns to the premises until informed that it is safe to do so [normally by the Fire Service].

Given the above, I'm entirely with you here - just why do people put FEs at exits if that exit is going to take the occupants out to a place of safety? In my opinion, it's because even now, a substantial majority of premises controllers either copy what others do 'cos it's easier than doing a proper FRA, or rely far to much on the advice of those selling/hiring the FEs [who don't even realise that they then have a liability for their advice as to which type & where it should go] and who naturally have a vested interest in getting the premises controller to take as many units as possible! More FEs = more money!!!

Another nonsense frequently given is that the Fire Service will use them as they go in to the fire. Given that UK firefighters have an incredibly deep distrust of anything that they don't absolutely know is not going to put their lives at greater risk; this doesn't stand up; I don't know of any competent UK firefighter who would even consider using a FE found on the premises that they're attending as even a third choice.

There, that should get a few people going!

I'm off to lunch now.

Frank Hallett

Posted By D. Hilton
Portable fire fighting equipment is provided so as to enable a trained user to extinguish an incipient stage fire, it is nonsense to suggest that this equipment is provided to aid a means of emergency egress from a location with a single means of escape.

A probable explanation for positioning at a final exit is that there is an increased probability of activating a manual call point prior to use of extinguisher. That is not to say that this equipment should not be provided at the likely point of hazard or within a reasonable travel distance.

Posted By D H
Mr Hilton - not its intended use I agree, but if you needed to break out of somewhere would a fire extinguisher - full or empty not be a useful tool?

Dave

Posted By D. Hilton
FAH
The main reason that Fire Service personnel would be less likely to use a portable extinguisher is typically due to a fire being at pre or at flashover on their arrival and so the PFE would be of no tactical use.

Posted By D. Hilton
Frank
Surely that would be the exception rather than the rule. If it was conceivable that ignition and fire growth would occur so as to trap the occupants in a non domestic dead end scenario, the travel from the extreme of the dead end could not exceed 9 meters until the choice of alternative means of escape.

Moreover, in the event that such accelerated fire growth is anticipated, it is more likely that the dead end scenario would have been removed at planning stage.

If portable fire fighting equipment was intended to be provided as a means to aid emergency egress then the provision and positioning would be considerably more prescriptive and would be included within AD B.

I am not saying an individual is prohibited from using this equipment as a means to aid egress I am stating that this was not the intent of providing this equipment.

In addition, if the HRR was to such an extent as to prevent egress, it would be most unlikely that the use of a fire extinguisher would reduce the thermal radiation to an extent as to allow safe passage or egress through the fire.

Regards
Darren

Posted By D. Hilton
crim
I dont know many builders with a 135

Posted By Crim
Darren fire fighters do not always use 135 ladders, in fact not very often, more likely to be short ex. Step ladders are often found in buildings and these were not to be relied upon. Anyway when I first started in the brigade we had 50 ft wheeled escapes, I never saw one of those on a construction site unless we brought it in, ha ha

Posted By D. Hilton
Quick calculation tells us that 9 litre water extinguisher could remove 20700 kJ of heat on complete vapourisation (more likely 13000 kJ at 55% efficiency).

This heat of combustion is the equivalent of 720g of cellulose.

unlikely to prevent escape.

Posted By Crim
Unlikely to prevent escape?

Posted By martinw
oh, get a room

Posted By D. Hilton
Any one spot the deliberate error LOL

Scrub that.

Lets also assume that the heat is radiated out equally in all directions (isotropic) and that an individual must pass within a distance of 1.5 m in order to escape.

A hypothetical sphere centred on the fire has an area of (4 . Pi . 1.5^2 = 28.26 m2)

In this case the fraction of heat flux impinging on 1 m^2 is calculated :

1200/28.26 = 42.46 kW/m^2

So individual would be well crispy !!!!

note to self (check calcs and less speckled hen before posting)

Burn rate would need to be 20 g/sec to result in successful escape.

In any event well beyond the capabilities of the fire extinguisher.

Posted By martinw
indeed Darren
is there a specialist FF forum by any chance to which I do not have access? If so, can you and Crim cage fight in there? :-) Love you all really