Help specifying fire extinguishers (powder vs. foam/CO2/water mist)

Apologies if someone has already mentioned this and Ive missed it but when it comes to water mist its easy to fall short of the points required by the boat safety scheme (and maybe your insurance?) although I suspect this may only apply to inland waters currently? According the the person I spoke this is due to them being relatively new to the market meaning they havent been officially certified to the extent of the older types rather than them not being up to the job. They also said that if they freeze while this will obvioulsy render them useless at the time they will be fine again when they thaw so theres no need to take them home over winter.

In the end I went with water mist throughtout the boat apart from and an auto FE36 in the engine bay. I also kept an old but in date AFFF onboard to give me the necessary points should the insurance company come looking, or if working on the boat in sub zero temperatures (why?)!
 
Last edited:
Uricanejack said:
I have the typical 2.5 Kg or 5lb powder type, for insurance purposes, because they are cheep, and they work if required. On A B and C fires.
I also have the little hole into the engine compartment. Again for insurance purpose, rather than actually expecting it to work. however I expect it will work as well as any extinguisher which I can find readily available.
Why, not Co2, Co2 would work as a fixed system, as an extinguisher not so much. Why not have you ever fired one off. and seen what happens to the diffuser. which will not fit through the little hole into the engine compartment any way.
Foam, foam is just water, with foamy stuff added, it works well and is ideal for class A and B fires( NA classes) so regular stuff and oily stuff.
Unfortunately not readily available where I sail.
My choice would be water mist.
Why, I have had personal experience, using(a fixed system not an extinguisher) Fuel oil fire in an engine space, fuel line sprayed onto hot, instant flare up, water mist activated instantly out. no damage.
Unfortunately, I have not found a local supplier of water mist extinguishers.

Those who mentioned fire blankets, personal experience, fire blankets work really really well for my kind of cooking mishap.

If you want to fight a fire fit a pump and a fire hose.

If you want to be able to prevent a tiny little fire turning into a fire. use an extinguisher. If it turns into an involved fire, see above. probably should have some form of fire suite and SCBA as well.
Click to expand...


You can buy them online and have them sent to you... or a convenient address.
 
Graham_Wright said:
Having watched the video, a scary scenario came to mind.
What happens if there is a galley fire and the flexible hose was leaking/pulled off its connector? (due perhaps to some previous violent movement)
Can you reach the shut off valve?
Mine is above the galley.
By the time one had understood, with a hose spouting flame and made the cockpit to shut off the cylinder valve, things could have become very serious.
Click to expand...
we fitted a solenoid in the gas locker, very easy and quick to isolate, it also isolates it outside the boat every time you use the stove.
 
Chaktoura said:
They also said that if they freeze while this will obvioulsy render them useless at the time they will be fine again when they thaw so theres no need to take them home over winter.
Click to expand...

Is this true? If so, that's great news! I opted for a couple of water mist extinguishers to replace a CO2 and AFFF this year and have had no choice but to leave them on board (wrapped in duvets!). I had assumed that freezing would cause permanent damage (not so much to the H2O - I understand how that works! - but to the extinguisher canister) and necessitate replacement? If 'normal' indoor winter conditions are very unlikely to cause permanent damage, then that's one less thing to worry about when prepping the boat for winter!
 
There’s a fair volume of water (1.4L in the smallest size), so I would still worry a bit about damage from freezing. Thus the duvets sound sensible!

Incidentally, all the AFFF extinguishers I could find on the main UK websites specify an operating temp above 2 degrees C. Apparently AFFF is manufactured/available with antifreeze additives, but these don’t seem to be widely sold.

It might therefore be that having an in-date powder extinguisher on hand is still advisable in the (less likely!) scenario of working aboard below freezing - or when first recommissioning from a ‘cold and dark’ state?
 
I have been considering water mist as replacement for my old, powder extinguishers and so have followed this thread with interest.
Videos showing water mist in action look convincing. It's great that it is so versatile, good for A, B, C and (to some extent) F fires and that it doesn't make a mess. But a closer look at the numbers (fire ratings) makes me a bit reluctant.
One way to compare the technologies would be to start at the physical size of the extinguisher. From the UltraFire range, these three happen to be about the same size (height 520 mm, diameter 160 mm): Powder 6 kg, Foam AFFF 6 litres, Water mist 3 litres.
This is how they come out (according to the specifications):
A fires: Powder 27, Foam AFFF 21, Water mist 8.
B fires: Powder 183, Foam AFFF 144, Water mist 13.
C fires: Powder Yes, Foam AFFF No, Water mist Yes.
It would be interesting to hear the reasoning from those in favour of water mist. Perhaps the much higher ratings for powder and foam on A and B are irrelevant in practice (overkill)? Or should one compensate by going larger if choosing water mist?
 
BabaYaga said:
It would be interesting to hear the reasoning from those in favour of water mist. Perhaps the much higher ratings for powder and foam on A and B are irrelevant in practice (overkill)? Or should one compensate by going larger if choosing water mist?
Click to expand...
  1. They are simple to use ;
  2. They can be used on all classes of fire found on a boat;
  3. Your vision is not obstructed when using them;
  4. They don't make a mess;
  5. You can breath when using them; and
  6. They won't give you frostbite (C02 might).
 
Sandy said:
Has anybody left a pot filled with water on their boat and checked if it had frozen in the UK?
Click to expand...
Not a pot of water but two half filled flexible water tanks frozen solid along with the fresh water pump which blew apart as a result. This was on Hayling Island so if it can happen here I'd say it is a concern!
 
syvictoria said:
Is this true? If so, that's great news! I opted for a couple of water mist extinguishers to replace a CO2 and AFFF this year and have had no choice but to leave them on board (wrapped in duvets!). I had assumed that freezing would cause permanent damage (not so much to the H2O - I understand how that works! - but to the extinguisher canister) and necessitate replacement? If 'normal' indoor winter conditions are very unlikely to cause permanent damage, then that's one less thing to worry about when prepping the boat for winter!
Click to expand...
I was told this by one of the fire safety specialists regularly recommended on this forum but admittedly it wasnt from the manufacturer. I shall make further enquiries next week
 
BabaYaga said:
I have been considering water mist as replacement for my old, powder extinguishers and so have followed this thread with interest.
Videos showing water mist in action look convincing. It's great that it is so versatile, good for A, B, C and (to some extent) F fires and that it doesn't make a mess. But a closer look at the numbers (fire ratings) makes me a bit reluctant.
One way to compare the technologies would be to start at the physical size of the extinguisher. From the UltraFire range, these three happen to be about the same size (height 520 mm, diameter 160 mm): Powder 6 kg, Foam AFFF 6 litres, Water mist 3 litres.
This is how they come out (according to the specifications):
A fires: Powder 27, Foam AFFF 21, Water mist 8.
B fires: Powder 183, Foam AFFF 144, Water mist 13.
C fires: Powder Yes, Foam AFFF No, Water mist Yes.
It would be interesting to hear the reasoning from those in favour of water mist. Perhaps the much higher ratings for powder and foam on A and B are irrelevant in practice (overkill)? Or should one compensate by going larger if choosing water mist?
Click to expand...
This is an interesting analysis/comparison - thanks!

Another factor to consider might be discharge time. For instance, according to the spec of the ones I've ordered, the smallest '1L+' (actually 1.4L) water mist runs for 12.5 seconds. It is approximately the same physical dimensions as a 2L AFFF, but that specifies only 6 seconds.

For that reason, coupled with the bulky size of the water mist extinguishers (the 3L is already pretty large to store neatly on a boat!), I'm not sure if you do need to go much larger. I've gone for the smallest (1.4L) water mist based on the effectiveness demonstrated in the videos, suggesting you could hopefully get a fair amount of 'fire fighting' achieved within its discharge time.
 
BabaYaga said:
I have been considering water mist as replacement for my old, powder extinguishers and so have followed this thread with interest.
Videos showing water mist in action look convincing. It's great that it is so versatile, good for A, B, C and (to some extent) F fires and that it doesn't make a mess. But a closer look at the numbers (fire ratings) makes me a bit reluctant.
One way to compare the technologies would be to start at the physical size of the extinguisher. From the UltraFire range, these three happen to be about the same size (height 520 mm, diameter 160 mm): Powder 6 kg, Foam AFFF 6 litres, Water mist 3 litres.
This is how they come out (according to the specifications):
A fires: Powder 27, Foam AFFF 21, Water mist 8.
B fires: Powder 183, Foam AFFF 144, Water mist 13.
C fires: Powder Yes, Foam AFFF No, Water mist Yes.
It would be interesting to hear the reasoning from those in favour of water mist. Perhaps the much higher ratings for powder and foam on A and B are irrelevant in practice (overkill)? Or should one compensate by going larger if choosing water mist?
Click to expand...
See post #61
I suspect the ratings for water mist will improve given time
 
Sandy said:
  1. They are simple to use ;
  2. They can be used on all classes of fire found on a boat;
  3. Your vision is not obstructed when using them;
  4. They don't make a mess;
  5. You can breath when using them; and
  6. They won't give you frostbite (C02 might).
Click to expand...
I agree that water mist has many advantages.
However, do these outweigh what seems to be, from the numbers, a much lower efficiency when it comes to putting out class A (wood and other solids) and B (flammable liquids) fires?
 
BabaYaga said:
I agree that water mist has many advantages.
However, do these outweigh what seems to be, from the numbers, a much lower efficiency when it comes to putting out class A (wood and other solids) and B (flammable liquids) fires?
Click to expand...
It might also be that it is 'only' water? So perhaps per volume, strictly speaking, it has lower fire retardant/suppression qualities than AFFF additives or chemical powder. But as you suggest above, this might be overkill as fires on board are less likely to be a factor of the volume of material on fire and more of the ability to put it out quickly and with a minimum of fuss/disruption/disabling of equipment. But I'm no expert whatsoever - as evidenced my initiating this thread to confirm what I ought to order!
 
Chaktoura said:
See post #61
I suspect the ratings for water mist will improve given time
Click to expand...
Hopefully. But I understood that more as improvement from technology development over time. Or did the person you spoke to imply that the water mist extinguishers sold today are more efficient than their ratings indicate?
 
Sandy said:
D you not have any electrics aboard? I consider electrics as the primary source of ignition onboard. Once that starts a flame there is a huge amount of combustible stuff aboard, wood, paper, clothing, bedding, pyrotechnics and rope.
Click to expand...
Not really. Properly fused circuits at 12 v should present no hazzard. Of course bundles of overloaded wire spurs etc might prove problematic but we're not specifying for such a mess it seems.

PWG
 
peter gibbs said:
Not really. Properly fused circuits at 12 v should present no hazzard.
Click to expand...

If my windlass cables were to chafe or have the insulation otherwise damaged, and partially short together, I wouldn't like to rely 100% on the 100-amp breaker definitely opening before some significant sparks had been released into whichever locker or furniture void. Of course the cables are mounted so as to make that unlikely as far as possible - but extinguishers exist precisely for when unlikely events nevertheless happen. The same applies to engine cables (less-sensitive overcurrent protection, but perhaps less physical exposure on a shorter run) and is probably true on a smaller scale for some other circuits like the fridge, autopilot motor, bilge pump, and dinghy-inflator socket.

Pete
 
As someone has already mentioned earlier, take a good look at your boat and identify realistic sources of ignition and carry out a basic fire risk assessment. Consider the likelihood of these sources causing a fire and take a good look of your storage of flammables etc. You can have a whole raft of different extinguishers but consider in the heat of the moment someone trying to firstly identify what is one fire, then make a decision as to which extinguisher to use. I would advise to keep it simple and not over complicate things whether you choose water and a fire blanket or foam and a blanket.

Also take a look at where your shut off valves for fuel. gas and batteries are and consider whether you can improve access to these in an emergency situation.
 
You must log in or register to reply here.

Share this page

Top