Fire Extinguishers

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christopherc

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The RYA Boat Safety Handbook says dry powder is not recommended for accomodation areas, and that foam is recommeded by the fire service. This surprises me, as it seems dry powder is the most common on boats. Any views? I need to get 2 or 3 for recently acquired boat, 2nd hand and it doesn't have any, token fire blanket only.
 
Dry powder is very hard to clean up completely, and it will corrode any metal objects that it comes into contact with. It damaged a copper lamp of mine.

Powder is chosen because it is the cheapest to buy. Foam is certainly good for small boat use. Carbon dioxide is also good, as is the new substitue for halon. However, expensive. But what is your life and boat worth ?
 
Powder is excellent for rapidly extinguishing a fire particularly fuel fires which os why mosy engine bay automatic extinguishers are powder. Nut, as mentioned already it is very messy and does not cool down the flammable source (didn't know about the corrosive asect of the stuff). I woud guess that accomodation fires will be largely wood/fabrics etc so foam would both extinguish and cool down the flammable source. I will be fitting halon substitute extinguishers in the engine room, and hope to install a mixture of foam and CO2 for the accomodation areas. I agree with Alan, what price is your life or your boat, so spending on safety equipment should at least equal spending on gadgets!
 
Foam is by far the most reliable extinguishant for most mixed fuel fires, blanketing the fire more effectively than others. They can be found here at very reasonable prices - well worth it for saving your life! Dry powder in an enclosed space can asphyxiate in no time - AFFF allows you to be in the space with the fire to fight it.
 
Foam is a great means of extinguishing, but it works best by allowing it to create a blanket over the top of a fire, and doesnt work very well when the source of the fire is raised up, wheeas dry powder will work in that situation. Undoubtedly the most effective all round fire extinguisher is AFFF, but you dont get that in a handy little extinguisher.
 
FInd your local extinguisher specialist (Non marine) and buy AFFF at sensible prices.
(AFFF = Aqueous Foam forming film) It's plain water but using a special nozzle that causes it to separate into tiny droplets that forms a film that smothers fire.
 
Dry powder can be very effective, and inexpensive, but its a bit of a mixed blessing.

Once had a dry powder extinguisher go unintentionaly off in the back of the car. Went round a bend, heard a clunk, followed by a hissing noise, followed by a white cloud advancing on me from the back of the car. Couldn't breathe, couldn't see the windscreen. Luckily, I had the drivers window partly open, so stuck my head out & pulled off the road. It took me a full day to clean the mess out of the car - had to remove all the seats, carpets etc.

Dry powder in the engine space is not the best solution. If the engine is running, the powder can be drawn in, possibly requiring that the engine be stripped down to clean up the mess.
 
AFFF is definitely not plain water. It is a special chemical added to plain water to enable the water to cling to what it is sprayed at, and bind together with other droplets of the AFFF, thus forming a film. Great stuf, really knocks fires down superbly. IMHO plain water extinguishers are so inferior they should be banned.
 
Plymouth Telephone Exchange many years ago had a fire. It was attacked with Dry Powder .... It had to be condemned and a new one built - as the powder had completely "gummed" up the system.

Dry powder only smothers a fire and actually at the heat source can harden up forming a barrier. But it has no cooling effect at all ....

It was interesting that some years ago - an incident highlighted use of Dry-Powder along with water spray ... the two combined to make an effective cooling and extinguishing blanket ... it had occurred not by design - but by accident. But of course that was a full blown Fire Service and not as we would have extinguishers. I only mention it as interest.

Halon was hailed as the greatest thing since sliced bread .... along with other extinguishing mediums as Hi-Ex foam ... It was claimed in various fileds that you could escape via a Halon / Hi-Ex environment .... sadly that proved not the case.

During my Merchant Navy Fire Fighting Training .... late 70's - the extinguishers and systems were changing rapidly ... it was amazing to see and actually use them against real fires ... the difference in performance was truly shattering.

One item that I will always remember - the lecture and demo of Vapourising Fluid Extinguishers ..... maybe some don't remember the small extinguishers sold to put in cars / kitchens etc. ? The effect of such in a confined area is deadly.

So what do I believe acceptable to me ? I have a presurised Foam ext. and a dry-powder job just inside cabin entrance ready to use ... A Fire-Blanket at arms reach from galley ... Another Dry-powder at mid-point of accom.
You may ask why I use DP when already it has been said to create such a mess ... The mess is a long way behind saving life ..... To live and then sort out the mess is better than not living ....

It falls into the same category as the point made by Camels Head Fire Station guys to us Cadets .... "First thought should be to survive ... get the people out whichever way you have to ... life is first !"
 
I was warned that dry poweder can compact over time, caused especially by typical boat movement and slamming in rough weather, and that such compacted cylinders might just vent gas if badly compacted. Is this fact or fiction? Another myth?
 
no - not another myth. the remedy is to turn the extinguisher upside down now and again and give it a good shake up to keep the powder loose. this also applies to domestics as the powder in them tends to settle as well.
 
Re: Fire Extinguishers ..... compacting

Any powder will compact over time and is reason that at intervals a DP ext. should be vigourously shaken to disturb and break up the contents.

In one shipping co. it was policy to invert the DP ext's at intervals in their holders for that very reason. A log was kept of that.

DP has an anti-compacting additive in it - so they say !! but still should not be relied on to keep it "flowing".

As to only getting gas out ..... normally CO2 ..... would be hard as generally the powder is against the foil seal in the nozzle...... or the bottom of the exit tube buried in the powder internally.

So .... what to do ? Case of the Okie Kokies - Shake it all about !!
 
The powder is designed to flow, even though it may settle, it would only not deploy in the most extreme compacted conditions. Periodically turn it over close to your ear, you should hear it flowing to the other end of the cylinder. If not, give it a gentle tap to get it going.

Some advocate mounting them horizontaly so there is less weight of powder per unit area of the base of powder to cause the 'alleged' problem.
 
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