Which Fire Extinguisher

[Malo37]

My boat, a Regina, is fitted with dry powder extinguishers. I have done a couple of advanced fire fighting courses in the past and was always advised never to use dry powder in an enclosed space unless wearing breathing apparatus. My personal experience which includes a house fire in which dry powder was used, is that once dry powder is released in an enclosed space it is near impossible to breath or to see. Dry powder also causes a huge amount of damage, especially to textiles (and probably to a running engine if ingested, not to mention electronics) and is extremely difficult to clean up afterwards. It also has no cooling effect on release. Another consideration is that dry powder doesen't always work 100% unless maintained correctly as the powder settles with time into a lump - they need to be inverted and shaken regularly.
My own preference for a boat is CO2 for an engine fire - with a suitable nozzel to introduce into the engine compartment, and CO2 or just plain water for the accommodation. Obviously CO2 can displace O2 and create a hazardous atmosphere, however if you are aware of this it has the advantage that it doesn't impare visibility and it does have quite a powerful cooling effect. You can fire it into the accomodation then shut the hatch and let it do its work.
I'm going to replace mine but would be interested to hear if anyone has a view on what extinguisher is best for a yacht, and meets legal and insurance requirements etc ?

 

[vyv_cox]

For an oil or fuel fire my preference is foam. It blankets the fire and provides a little cooling. I share your misgivings about powder and have personally witnessed re-ignition of an engine fire previously extinguished by it.

 

[Chris_Robb]

My boat, a Regina, is fitted with dry powder extinguishers. I have done a couple of advanced fire fighting courses in the past and was always advised never to use dry powder in an enclosed space unless wearing breathing apparatus. My personal experience which includes a house fire in which dry powder was used, is that once dry powder is released in an enclosed space it is near impossible to breath or to see. Dry powder also causes a huge amount of damage, especially to textiles (and probably to a running engine if ingested, not to mention electronics) and is extremely difficult to clean up afterwards. It also has no cooling effect on release. Another consideration is that dry powder doesen't always work 100% unless maintained correctly as the powder settles with time into a lump - they need to be inverted and shaken regularly.
My own preference for a boat is CO2 for an engine fire - with a suitable nozzel to introduce into the engine compartment, and CO2 or just plain water for the accommodation. Obviously CO2 can displace O2 and create a hazardous atmosphere, however if you are aware of this it has the advantage that it doesn't impare visibility and it does have quite a powerful cooling effect. You can fire it into the accomodation then shut the hatch and let it do its work.
I'm going to replace mine but would be interested to hear if anyone has a view on what extinguisher is best for a yacht, and meets legal and insurance requirements etc ?

CO2 is normally required in huge volumes when injected into accommodation, and even into a small engine room. So on yachts without a proper fire shutdown to exclude O2 is not really a practical solution - you would need quite large cylinders. CO2 is also extremely dangerous as you will last anly a VERY short time - not enough time to get out, in a pure C02 atmosphere.

The new engine extinguisher stuff works, but its no good if the engine is still running as it will be extracted within seconds by the exhaust system. So much thought needed in how you set up your system - an automatic one is probably not suitable unless it also stops the engine.

 

[Doug_Stormforce]

My boat, a Regina, is fitted with dry powder extinguishers. I have done a couple of advanced fire fighting courses in the past and was always advised never to use dry powder in an enclosed space unless wearing breathing apparatus. My personal experience which includes a house fire in which dry powder was used, is that once dry powder is released in an enclosed space it is near impossible to breath or to see. Dry powder also causes a huge amount of damage, especially to textiles (and probably to a running engine if ingested, not to mention electronics) and is extremely difficult to clean up afterwards. It also has no cooling effect on release. Another consideration is that dry powder doesen't always work 100% unless maintained correctly as the powder settles with time into a lump - they need to be inverted and shaken regularly.
My own preference for a boat is CO2 for an engine fire - with a suitable nozzel to introduce into the engine compartment, and CO2 or just plain water for the accommodation. Obviously CO2 can displace O2 and create a hazardous atmosphere, however if you are aware of this it has the advantage that it doesn't impare visibility and it does have quite a powerful cooling effect. You can fire it into the accomodation then shut the hatch and let it do its work.
I'm going to replace mine but would be interested to hear if anyone has a view on what extinguisher is best for a yacht, and meets legal and insurance requirements etc ?

A few thoughts

As effective as water is its pretty heavy to carry in an extinguisher- there is of course a plentiful supply nearby.

You mention the cooling effect of CO2 and then refer closing the hatch to the accommodation space. There would still be enough Oxygen in there to burn the yacht down to the water line, closing the hatch therefore increases heat and is the opposite of what you want to do. CO2's main use is in smothering the fire from Oxygen, however it will disperse quicker than powder (which also smothers).

As far as the stowage problem of the powder extinguisher goes try fitting its bracket horizontally across the vessel so the extinguisher is pointing to port and starboard, this means every time you tack the powder is being shaken up for you.

Personally I favour powder extinguishers and a couple of buckets with lanyards. (partly for weight and stability reasons). I take your point about the engine not reacting very well to powder but think the priority is to save the yacht from burning down to the waterline not to maintain use of the engine. As all ways everything on board a yacht is of course a compromise.

 

[Malo37]

There is no risk of asphyxiation in the event of discharging 2 Kg Co2 extinguisher within a space of 15 m3 volume, even assuming zero ventilation/no air change.

Volume of space = 15 m3
Density of CO2 gas NTP = 1.87 kg/m3

Volume of O2 in confined space : 0.21(15m3-(2kg/1.87kgm3)

= 0.21(15-1.0690
=0.21((13.93)
= 2.92 m3 O2

Concentration of O2 in room: (100*2.92m3)/15m3 = 19.5%

No risk of asphyxiation, especially as for you to get in the hatch will be open anyway.I agree that my comment about closing the hatch is questionable.

Foam is fine for pool fires but unless you have a pool of fuel on fire under your engine it is an unlikely event on a yacht, and 2kg of CO2 into your engine box should extinguish that immediately. I think, and correct me if I'm wrong, that most yacht fires would be likely to be initiated by some kind of electrical problem.
If you fire off a dry powder in the accomodation, you can neither breath or see - seriously it's worth trying one out in the garden shed so you know what to expect, and your boat is ruined.

 

[Alfie168]

If there is no risk of asphyxiation with Co2 then that dictates that there must still be plenty of oxygen around. There is a contradiction inherent here as the effectiveness of Co2 depends on the exclusion of oxygen. No problem in an engine compartment if you can seal it and flood it with Co2, but probably not so clear cut down below, unless it is something localised like a pan fire

I don't have a 'clever' answer to your question. I'd get advice from the RNLI and the Fire Service who must know more than most. Either way as long as you have a fire strategy you have thought through, and an escape strategy, thats more than many will have done, and its all you can do.

Some idiot let off the powder extinguisher in my daughter's car as a prank whilst they were driving along. It cleared up OK. In any event the damage from the fire would concern me more than the powder, but as you say, none of these things are risk free.

Tim

 

[Cymrogwyllt]

Anything more than the smallest fire (The type smothered by a fireblanket ) and it's probably time to step over the side. Way too many toxic fumes if anything bigger. I venture to say that a smoke mask and escape strategy is a better investment than an extinguisher.

 

[Doug_Stormforce]

.....If you fire off a dry powder in the accomodation, you can neither breath or see - ...................and your boat is ruined.

This was my earlier point- Your boat will be more ruined if you don't put the fire out!

 

[Malo37]

This was my earlier point- Your boat will be more ruined if you don't put the fire out!

I'm obviously not suggesting you don't put it out. I'm suggesting you should put it out more efectively and in a way that does the least damage.

 

[maxi77]

I have also moved away from dry powder though there are still a couple on board. The engineroom is covered with and auto halon replacement, and as a back up there is a foam in the cockpit and by the galley. I suspect CO2 is OK for the engineroom as long as you do not ventilate, but other than quick knock down of limeted fires such as electronics little value. We used CO2 in submarines but that was total flood and any one inside needed breathing kit, some how I do not see that working in a yacht. By the way 20% CO2 in the atmospher you are breathing is not good for you at all, even a small percentage increase will start to make you noticably sleepy, 20% is a h*ll of a lot.

 

[PilotWolf]

I am surprised that the fire course didn't let you try to put out a 'solids' type fire with CO2 - I think we tried it on a stack of burning wood/paper... it don't stay out!

CO2 for electrical fires. Foam or AFFF for fuel/solids. Fire blanket for galley.

Any gaseous smothering needs a good seal-able area or its not going to work and again no cooling so ideally need to consider boundary cooling and not re-enter the area for sometime. The MAIB report into the Calypso fire a couple of years ago makes interesting reading regarding CO2 systems.

We have a Pyrogen system in the engine room but it is not automatic because if the engines aren't stopped and the engine room fans stopped its all going to waste.

Most of the small extinguisher that you buy in Halfords, etc. are a waste of time - some have a 16 second or less discharge period. By the time you squeeze the lever, realise it is working and point it in the right direction it has run out. Buy the biggest that is practicable and affordable.

Tend to agree best option is often going to be the bucket of sea water and if that's not working its liferaft time.

But the best idea is good house keeping and be anally retentive towards fire prevention. In around 25 years of playing with and working on boats I have had one fire and it is not something I would like to repeat - and to this day I don't know if we put it out or it burnt itself out

W.

 

[peterb]

You mention the cooling effect of CO2 and then refer closing the hatch to the accommodation space. There would still be enough Oxygen in there to burn the yacht down to the water line, closing the hatch therefore increases heat and is the opposite of what you want to do. CO2's main use is in smothering the fire from Oxygen, however it will disperse quicker than powder (which also smothers).

I worked for 20-odd years at the Fire Research Station (and at one time was responsible for testing fire extinguishing foam). One series of tests was concerned with window breakage in fires. In work on fire resistance of modern structural materials we had found it difficult to get a big fire going unless either a door or window was open. We tried two fires in closed rooms (in a pair of semi-detached houses, so the rooms were mirror images of each other). One fire used 'traditional' furniture (horsehair stuffing, etc) while the other used modern PU foam. Both fires gave initial high temperatures, but both then died away to slow smouldering. In both fires the total amount of fuel burnt was equivalent to half an armchair, after allowing the fire to 'burn' for over an hour. The room was black with soot, but the paint on the woodwork had not blistered.

Most of the material burning in a fire will be hydrocarbon. Although it may be in long chain molecules, for simplicity it can be considered as CH2. Its burning can then be taken as

2CH2 + 3O2 = 2CO2 + 2H2O

That says that 28 gms of fuel needs 96 gms of oxygen to burn. In practice the fire will drop to slow smouldering when half the oxygen has been burnt, so those 28 gms will need an initial oxygen supply of 192 gms. But the oxygen only makes up 21% of the air, so we need 914 gms of air. At room temperature air weighs about 1300 gms per cubic metre, so one cubic metre of air can only burn about 40 gms of fuel.

How many cubic metres of air are there in your cabin? Say 2m high, 3m wide and 4m long. About 24 cubic metres. Not quite enough to burn 1 kg of fuel.

The problem, though, lies in closing the cabin. Find the washboards, fit them (with flames coming out of the hatch) then close the hatch. That's why I've always preferred hinged doors to washboards.

 

[Bru]

There was a similar thread on this subject some while ago to which I posted my experience of using various types of fire extinguisher on a fire marshall training course ...

http://www.ybw.com/forums/showpost.php?p=2860058&postcount=8

You may find it helpful ... then again you may not!

BTW, in the end, contrary to what I said in that post, we fitted Brigantia with two 2kg AFFF extinguishers and a fire blanket and didn't bother with the CO2 at all as on reflection we decided it wasn't worth the bother of having them - any fire we can't kill with either the blanket, the AFFF extinguishers or buckets of seawater is not going to be put down by CO2

 

[Malo37]

Interesting stuff. My concern was really that having some extinguishers on board does not help much unless they are the right size and type and you know how to use them. I'm just concerned that there seems to be a default to dry powder without full realisation of its performance or side effects in use. My boat has one in the forecabin, presumably to help anyone trapped in there to make an escape, another adjacent to the galley - with a fire blanket, one at the engine room and one in the cockpit. I am probably going to change them to water with CO2 for the engine, and the bigger cockpit one I'm as yet undecided but maybe water again. I believe there are new tech water mist extinguishers available somewhere but where?

 

[Doug_Stormforce]

2CH2 + 3O2 = 2CO2 + 2H2O

That says that 28 gms of fuel needs 96 gms of oxygen to burn. In practice the fire will drop to slow smouldering when half the oxygen has been burnt, so those 28 gms will need an initial oxygen supply of 192 gms. But the oxygen only makes up 21% of the air, so we need 914 gms of air. At room temperature air weighs about 1300 gms per cubic metre, so one cubic metre of air can only burn about 40 gms of fuel.

How many cubic metres of air are there in your cabin? Say 2m high, 3m wide and 4m long. About 24 cubic metres. Not quite enough to burn 1 kg of fuel.

The problem, though, lies in closing the cabin. Find the washboards, fit them (with flames coming out of the hatch) then close the hatch. That's why I've always preferred hinged doors to washboards.

I am not going to argue with your numbers, they sound great in theory but;

1/. How long does it take for the fire to burn through the hull and effectively re supply itself with oxygen after you have helped it by increasing its heat?- Not long.

2/. Is a yacht really airtight once you close the hatch? No.

3/. Can you fight the fire with anything else available (buckets of water for example) once you have closed the hatch? Besides some ineffective boundary cooling, No.

While the "close the hatch and deprive the fire of Oxygen" theory sort of makes sense for a small enclosed space such as an engine compartment I don't buy it for the whole accommodation space down below. My own preference would be to turn the yacht downwind so that cool air was blowing in the biggest opening (the hatch) while I attempted to fight the fire.

As every fire fighter learns on Day 1, a fire needs Oxygen, heat and fuel, if you can take away any of these three things you will fight the fire, if you add any of these things you will feed the fire.