AFFF fire extinguishers

Magnum

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Has anyone actually used one in anger onboard? Am thinking about buying some for our new boat with a largish CO2 for electrical fire risk.
 

aztec

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I use AFFF regularly. If it's any recommendation, it would be the one i'd choose before anything else (yes i know i'm tempting the armchair experts here, but it works exceedingly well). I also use Dry powder, and can honestly say that i wouldn't have it on the boat.

I would however have a CO2 as it's also a good tool for some things where clean up may be a problem (even after a small fire you still need to operate).

My preference would be two 9 liter stored pressure AFFF units covering the engine bays, with an additional portable available on the bridge/helm. but then mine' s only 30ft.

Hope this helps.
 

Magnum

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We have an automatic built-in system for the engine/gen room, but I was thinking about a small AFFF for each of the 3 cabins, a larger one for the cockpit and saloon and a medium sized CO2 for electrical use.
 

aztec

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AFFF in favour of DP in any enclosed space. also DP is rated for A,B and C. but to be honest is pretty ****e on anything other than dry gas. AFFF's use on a B class is unsurpassed, therefore it's use on A class (like bedding, wood, GRP etc) is equally good. certainly within a compartment, the visibility issue is reason enough, then you have the lack of cooling to consider. AFFF has about 4% foam concentrate to 96% water so cooling of an A class material is as effective (if not more so) than water alone.
 

aztec

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Don't be too worried about electrics below 240V, the main risk with water or foam on electrics is the risk of electrocution.

on low voltage electrics or higher voltages that can be isolated before application of "wet" media, you can treat as the base fire e.g A,B,or C
 

aztec

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What about use on class C fires?

oops missed this one.

Class C or fires involving gasses can really only be tackled in two ways, isolation of the supply with localised fire fighting on any resulting class A, or in the case of a gas fed flame that fails to impinge on any other fuel, DP alone can extinguish the flame/radiated heat, but then unless you can isolate and make safe, you will still have gasses leaking and available to any ignition source.

i'd still not have DP abourd, if it got that bad, i'd not fire fight, i'd be in the raft watching my insurance excess going up.
 

Bru

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At the risk of being accused of being an armchair expert, 'cos I'm in my favourite armchair as I type :), here goes ....

I have used a dry powder extinguisher on board a boat. I've also used every type of extinguisher going under controlled conditions on a fire training course.

Dry powder is about as much use, actually probably less use in fact, as getting your todger out and p*ss*ing on the fire. It works by starving the fire of oxygen. Therefore, it will not fight a vertical fire - if your curtains have gone up it's, er, curtains. Nor does it cool (to any extent) the combustible material so even though it may knock down the flames, if the blanket of powder is disturbed too soon reignition can occur. Dry powder also makes a horrendous mess. If it gets inside any hot equipment that equipment is pretty much b*gg*r*d. Cleaning it up is no fun. It has one crucial advantage - it is almost 100% "safe" as far as the operator of the extinguisher is concerned.

CO2 is even more useless than dry powder. Do not bother with CO2 extinguishers on a boat - they are noisy, ineffective on most types of fire and if used wrongly can lead to freeze burns - you never, ever, hold a CO2 extinguisher by the horn or bottle (it must be held by the handle). The one type of fire where CO2 is potentially useful is an electrical equipment fire (e.g. computer gear, switch panels etc.) which is why we always have CO2's at the amp and lighting racks and the control rostrum at gigs. With the power isolated (to cut the source of further heating) a CO2 will knock down the flames in a fried piece of kit without ruining all the other gear around it. However, on a boat, let one off in a cabin and ...

Foam (AFFF) is the "weapon" of choice for dealing with liquid fires (oil, petrol etc.) and it's also effective against general class A/B fires. However, consider that it works most effectively against spilt liquids by the primary method of forming an oxygen depriving film on the surface of the liquid. In order to do so, the liquid must be on a flat(ish) surface or contained within an area in some way. Burning petrol, for example, on a sloping surface or in an inaccessible place could obviate the formation of the film leaving secondary cooling as the only effect which may or may not work. Foam is not good on electrical fires!

All of the above is all very well but there is one crucial point missed about ALL of the available extinguisher types on board our (relatively) small boats - they are invariably too small to be any use against anything but the smallest of fires. They are exhausted astonishingly quickly and, in the small sizes used on boats, are useless against anything beyond a very small localised fire

I will tell you a tale. It is a tale of 12 fire training course students, one pint of petrol and a concrete gutter about 3 metres long. The training instructor (a fire officer with 30 years experience) poured the petrol into the gutter and lit it, from a distance of course!

In front of us was the most impressive array of fire extinguishers you could hope to see. Dozens of 'em. All big industrial size ones like you'd see in factories, not titchy little 1kg and 2kg things. We started with CO2 and the inevitable "girlie" on the course was selected to have the first go (well, even senior instructing fire officers need a laugh from time to time). She nearly freaked out when the thing went off (they are SERIOUSLY noisy!) and completely missed the fire with the entire bottle. We all then proceeded to blast this fire, 1 pint of petrol remember, with another 4 or 5 5kg CO2 extinguishers. Was it out? Was it hell.

We then hit it with 5kg of dry powder. Only one 'cos that made enough mess of the fire station yard. The fire appeared to be out. The instructor said we could "stand easy", as it were, and those who did could smoke. So we had a smoke. After five minutes or so, he stirred the liquid in the gutter with a long stick and the fire promptly reignited. Although the powder blanket had deprived the fire of oxygen it had not cooled the petrol below the flash point and even after five minutes it was hot enough to reignite

Then we tried foam. It worked better than either of the other two in that it put the fire out easily provided the foam was applied correctly - starting at the far end of the fire and laying down a foam blanket working towards you. Aim it directly at the fire and you'll spread the burning liquid all over the place. Again, like the dry powder, once the blanket of form was formed the fire appeared to be out. This time, a simple stir of a stick produced no reignition because the foam also cooled the petrol down below the flash point. It took two extinguishers to extinguish the fire. Job done - well, yes but with the proviso that this was a "perfect" scenario for foam i.e. a liquid fuel fire in a confined container where it could form a proper film over the surface.

Remember these were big 5kg and 10kg extinguishers and the fuel source was just one pint of petrol. Even in ideal circumstances with detailed instruction and supervision from an expert, we struggled to put that fire out under completely controlled conditions with any of the extinguisher types, even foam.

The instructor then said that there was only one effective way to fight any fire of that size or larger and pointed to ... the big red fire engine :)

It was also demonstrated, in various scenarios, that a decent size fire blanket is often more effective at tackling a small fire than any of the extinguishers - they are not just for chip pan fires! A fire blanket dealt effectively with a waste paper basket fire, far better in fact than dry powder would do, and is also good for any fire in a confined area where you can smother it with the blanket. They are also good for dealing with the horror scenario of somebodies clothes catching alight.

There is one fire fighting facility we have on a boat that is too easily overlooked - we have access to an unlimited quantity of H2O. A sturdy bucket on a lanyard, readily to hand, is probably a better bet in most circumstances than any of the viable extinguishers - and even if the initial knock down of the fire is by dry powder or foam extinguisher it's almost always going to be a damn good idea to heave a good few buckets of water onto the job to ensure it's cooled right down and prevent reignition.

Brigantia has one old life expired dry powder extinguisher on board which needs replacing. I plan to fit 1 2kg dry powder in the cabin and a further 2kg AFFF in the cockpit area. You may ask why the dry powder given what I said above but a small (and 2kg is small, don't even bother with 1kg) dry powder is the least worst option for tackling small fires like a fat fire in a pan on the cooker, a meths spill (we're fitting an Origo spirit stove) or a fire in the electrical kit (as long as it's followed up). The AFFF extinguisher is primarily for dealing with petrol spill fires as we have a petrol outboard and, inevitably, will from time to time have no option but to refill the main tank from spare cans when afloat (a practice best avoided of course but in the real world sometimes it has to be done)

We will also have the aforementioned bucket which will be a critical part of the fire fighting inventory - not a repository for junk! - and a fire blanket adjacent to the galley.

What I found particularly instructive, and rather scary, on the fire course was the demonstrations and videos of various fires and just how fast they can develop. A fire can go from a "oh, look, it's smoking" situation to an "oh, sh*t, we're dead" scenario in a matter of seconds. Although no boats were depicted on the videos, there was a caravan and that went from a flash fire in a frying pan of oil to a flaming pyre in under a minute.

By all means have the requisite means of fighting fires - and a plan and fire drills with your crew if you've got any sense - but consider that if you haven't dealt effectively with a SMALL fire within the first 30 seconds or so it will probably be time to consider abandoning ship - and I am deadly serious. Once the fire has spread beyond the initial ignition point (whatever and wherever that may be) and caught hold in secondary sources of fuel (woodwork, upholstery, curtains etc.) your chances of beating it are virtually zero so your fire plan needs to include an abandon ship procedure (even if you haven't got a liferaft - it's the one time getting off is likely to be the ONLY option)

Bru
 

Seajet

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Another point about dry powder which is often overlooked is, it's very corrosive.

I had a small fire aboard a boat under way when the flexible gas hose to the gimballed cooker ruptured ( had just bought the boat secondhand and found out the hard way that armoured hose is to be avoided at all costs, one can't see internal condition ).

The fire was quickly out via a combination of self with small but directly to hand 1kg dry powder unit, and crew turning off gas in cockpit at the bottle.

However after the excitement we relaxed, and got on with sailing ( it was a good F6 off Eddystone and we had no liferaft, if things had gone badly with the fire it could have been a bad day ).

By the time we got into Fowey and cleared up, the woodwork around the cooker was irredeemably pitted, the only damage from the fire...
 

Bru

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To add to my earlier post ...

Seajet is spot on about DP being corrosive and it's also very sticky too! When our caravan was totalled by a sideswipe from a passing artic, the dry powder extinguisher on board went off and pebbledashed the side of my Landrover 109. It was a complete **** to clean off and left little dimples in the paintwork (not that you'd really notice, the paintwork wasn't much to write home about anyway)

The other thing I forgot to emphasise, which others have already mentioned, is the importance of isolating the fuel or heat source in the case of electrical and gas fires - in either case, turn off the power or gas at source before even tackling the fire (or better still, if possible, have one crew tasked with isolating the supply whilst others tackle the fire)

This is especially important with electrical fires which will often go out entirely without any further intervention when the current flow is stopped thus removing the source of the heat which caused the fire in the first place.

Remember the "fire triangle" - fires need three things, fuel, heat and oxygen. Remove any one of them and the fire will go out. When we had the fire on our narrowboat Badger, which was caused by an electrical fault you'd never have found in a million years due to a hidden bodge by a previous owner, isolating the supply by killing the engine (the fire was in wiring connecting the engine alternator to the electrical system) worked perfectly. We hit it, probably needlessly, with a DP extinguisher for good measure and rather wished we hadn't!

If we'd left the engine running we could have pumped as much dry powder at it as we liked and it would have done no good whatsoever - with a high current flowing up what had become a virtually incandescent filament the fire would have kept reigniting (and would probably have torched the boats wooden cabin soon enough). What still gives me the shivers is that the fire broke out as we arrived back at our mooring - just half an hour earlier we were deep underground half way through a 2 odd mile tunnel :eek:

By the way, my oppo and part owner of Brigantia Rik has just Skyped me to say that Farnell CPC have got a special offer going on fire extinguishers and fire blankets at prices somewhat below what the chandleries charge - they also do 2kg AFFF which none of the chandleries seem to offer

Bru
 

Magnum

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Brigantia, great information. Thank you.

I'm going to go for some 2KG AFFFs in the cabins with larger ones in the cockpit and galley/saloon area. On the basis of your advice I'm also going to buy several fire blankets as they are so cheap, light and effective. Would you say 1.2x1.8m is big enough?

I still may add a CO2 unit in the saloon/galley. We have quite a lot of electrical equipment and it just seems sensible to have this backup.

One other thought regarding cutting off the source of any potential electrical fire is to turn off our inverters when not required and especially at night. That way we will not have 240v routed round the boat needlessly.

We will also most definitely make sure we have a fire bucket with rope easily accessible in the cockpit.
 

Bru

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Hi Magnum,

I wouldn't go overboard with fire blankets - one, or maybe two on a larger boat, well located is plenty. You need to consider where a fire might break out (e.g. cooker) and where you want to be to be able to safely grab the blanket and deploy it. It might be worth having one near the galley and one near the engine (which idea has made me think actually, although on Brigantia nothing is going to be more than a few feet away 'cos she ain't very big!) but anything you can't deal with using one standard sized blanket (1.2x1.8 is fine) is probably too big to tackle anyway (maybe with the exception of a fuel spill but your AFFF extinguishers will deal with that just as well or better)

Another word of serious caution about CO2 - although they are good for electrical fires and as I mentioned earlier we do deploy them at gigs, this is because we are running a LOT of very high power kit (amp racks, lighting dimmer racks, 63A 3 phase distro racks etc.) that gets very hot and once in a blue moon something gets definitely toasty and we don't want to destroy £30k or £40k worth of kit putting out a fire in a single amp (or whatever) that costs maybe £1k!

On a boat, I really doubt these considerations apply. An electrical fire is much less likely to happen (the one we had on Badger was an exceptional situation) and if you have a fire on a boat you have far more important things to worry about than whether you're electronics survive - they can be replaced, you can't!

I would also be EXTREMELY reluctant to fire off a CO2 extinguisher in a confined space like a boat cabin. I don't think it would actually kill you but I suspect that it would be seriously unpleasant. If you've never seen and heard one used you probably have no idea just how noisy they are nor how much gas they pump out - remember they work primarily by replacing the air around the fire with CO2 gas thus depriving it, and potentially you as well, of oxygen!

The noise could be seriously disconcerting too - the poor lass who got lumbered with having the first crack with the CO2 had several goes and every time it scared her rigid to the extent that she was completely unable to use it effectively ... and I have to say that even having seen her struggle with it and knowing what to expect I did not find the damn thing easy to use either and that was outside in the open air!

Oh and turning off the inverters is not a bad idea - apart from anything else they'll be using standby power even when there's no load on them so fire risk aside it'll save your batteries :)
 

PaulJS

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One very important point

Some very good advice here, however one thing I would ask everyone to remember is never, ever try to fight a liquid fuel based fire with water.
If water gets into hot oil or fuel which has already been smothered or extinguished it instantly vapourises, this has the effect of throwing the nice hot oil into the air in a nicely atomised form, so then you possibly have all three elements of a fire:

Fuel

Oxygen Heat


As the fuel is effectively atomised it has a massive surface area in contact with oxygen, and if it's above it's self ignition temperature, it WILL burn. At explosive speed.

I've actually had great success fighting a fire with a DP extinguisher, but they are messy. My personal recommendation is for halon extinguishers, but unfortunately they are no longer available as "halon is a CFC and can deplete the ozone layer" - although probably not as much a burning boat would.
 
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PetiteFleur

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Brigantia's information is very soberering - thanks.
I've also converted to AFFF extinguishers last year. What prompted it was the total mess a friend had in his house after putting out a small fire with a dry powder type - they were still finding the powder for days afterwards(it did put the fire out though!) I also understand that the powder can really mess up your engine if used in the engine bay.
So I have an automatic Halon replacement in the engine bay, one 1kg AFF in the rear cabin and two in the saloon + a fire blanket.
 

Cymrogwyllt

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Thanks Brigantia.

As you have said anything more than a very basic early stage fire it's 'look for an exit time'. At home every room has a 'get out route' separate from the usual means of entry/exit. Should be the same for boats.

Wroking in a school lab the little darlings loved to set fire to things. The rule was 'If thinking about needing an extinuisher get everyone out and get the office (send a couple or three messengers) to call the big red lorries, then get neighbouring classes out and then try and tackle if safe to do so. Luckily I never had to follow that route.
 
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prv

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Wroking in a school lab the little darlings loved to set fire to things.

I once got seriously told off for setting fire to things in a Chemistry lesson. I felt very hard-done-by as I was actually trying to put out a small fire that some idiot had started. Noone had told us that the soap solution used in the experiment, which I grabbed as the first thing to hand to pour over his stack of burning splints, was actually alcohol-based and quite flammable!

Pete
 

PCUK

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I was trained on using AFFF on the railway. The instructor sprayed it onto 700 volt third rail to prove that it is OK on electrical fires. (Each droplet of foam is separate from the next so doesn't conduct electricity when being sprayed). The reason it is no longer recommended for electrics is if the nozzle gets damaged or stolen (being brass) then the foam is not formed and a stream of water is the result.

Certainly on 12 volt you would never have a health and safety issue.
 

Magnum

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Interesting PCUK.

All this advice is very useful. Thanks all.

I'm going for AFFFs throughout - 1 small in each cabin, i larger one in saloon/galley and cockpit. I'm still going to buy a small CO2 as backup. Plust 2 fire blankets and a bucket and line.

I think that's a fairly sensible setup.
 
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