Choosing engine fire extinguisher

Uricanejack said:
The flash point for diesel is between 61 and 64 degrees C depending upon the grade of gas oil. Which may seem quite high compared to other flammable liquides. Even so, I would not recommend putting a match to diesel.
You only need three things for a fire. Fuel, air, (O2) and heat.
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Well if Devon and Somerset Fire Service are happy to put a lit rag to a pan of diesel on my fire warden training and it not ignite, that is good enough for me. Doing the same to a pan of petrol was quite spectacular.

Perhaps we should all so some Citizen Science and take the max temperature in the engine room/compartment next year and see what range of temperatures we have. I'd be surprised if they are anywhere near the flash point. For those with the technology we could take the temperature of the engine hourly. I think my multimeter would do that, I'll check next time I am on the boat.
 
KellysEye said:
Powder destroys the electronics so use a CO2 fire extinguisher. I didn't install and an automatic fire extinguisher in the engine room because smoke from a slipping fan belt creates smoke and needlessly sets it off. The CO2 extinguisher was installed opposite where the engine was.
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CO2 will not cool the place only starve the fire of O2. If the engine is running powder can be ingested. If Foam is used it MUST be approved for use with electrical equipment - like the Royal Navy use.
 
A correctly specified air filter should stop dry powder being ingested. If I had an engine room fire, my main concern would be putting the fire out. Engine damage, if any, can be fixed later.

I have seen a dry powder go off in an engine room, accidentally, while the engine was running. Yes it made a hell of a mess, but the engine was undamaged and there was no long term affects.
 
Sandy said:
Well if Devon and Somerset Fire Service are happy to put a lit rag to a pan of diesel on my fire warden training and it not ignite, that is good enough for me. Doing the same to a pan of petrol was quite spectacular.
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Our resident company fire officer used to give lectures and demonstration to staff. He had a closed tobacco tin containing petrol. He would apply a lighted taper once opened and the petrol burned. He then closed the tin and continued talking. He repeated the ignition which was a little more interesting. He then closed the tin again. The third time of lighting was spectacular.

The point of the demo was to illustrate the necessity for heat.

Very illuminating.
 
Sandy said:
Well if Devon and Somerset Fire Service are happy to put a lit rag to a pan of diesel on my fire warden training and it not ignite, that is good enough for me. Doing the same to a pan of petrol was quite spectacular.

Perhaps we should all so some Citizen Science and take the max temperature in the engine room/compartment next year and see what range of temperatures we have. I'd be surprised if they are anywhere near the flash point. For those with the technology we could take the temperature of the engine hourly. I think my multimeter would do that, I'll check next time I am on the boat.
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I've been monitoring the temperature of my MD2020 this year (having just replaced the heat-exchanger housing). I've been doing this with a cheap infrared thermometer. The highest (surface) temperature I measured was a little under 90C after a few hours running at 2500rpm in a warm France this summer.
 
Graham_Wright said:
I once accidentally stood on a prone CO2 extinguisher whilst wearing shorts. Straight up the divide. It is cold, very cold!
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True that is why they have a horn and when we had training were told not to touch it. You will know the physics.

How CO2 works is by O2 starvation not cooling.
 
JohnGC said:
I've been monitoring the temperature of my MD2020 this year (having just replaced the heat-exchanger housing). I've been doing this with a cheap infrared thermometer. The highest (surface) temperature I measured was a little under 90C after a few hours running at 2500rpm in a warm France this summer.
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Thanks JohnCG.

In one instance we have a temperature where diesel could be ignited on contact with a hot surface.
 
KellysEye said:
Powder destroys the electronics so use a CO2 fire extinguisher. I didn't install and an automatic fire extinguisher in the engine room because smoke from a slipping fan belt creates smoke and needlessly sets it off. The CO2 extinguisher was installed opposite where the engine was.
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What type of smoke sensor do you have that sets off your extinguisher?

www.solocoastalsailing.co.uk
 
Plum said:
What type of smoke sensor do you have that sets off your extinguisher?
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You won't get a sensible answer. He posts that sentence almost verbatim every time the subject of engine bay extinguishers comes up, I point out that the automatic extinguishers used on yachts are triggered by heat and not smoke, and he doesn't respond. I only bother because I don't want newbies to be mislead, I don't expect him to learn or stop doing it.

Pete
 
prv said:
You won't get a sensible answer. He posts that sentence almost verbatim every time the subject of engine bay extinguishers comes up, I point out that the automatic extinguishers used on yachts are triggered by heat and not smoke, and he doesn't respond. I only bother because I don't want newbies to be mislead, I don't expect him to learn or stop doing it.

Pete
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I agree with pete here that is why I has a smoke detector in the engine compartment and a manually operated extinguisher also in the engine compartment this gives me chance to shut down the engine if I can before setting the extinguisher off.
 
Sandy said:
Well if Devon and Somerset Fire Service are happy to put a lit rag to a pan of diesel on my fire warden training and it not ignite, that is good enough for me. Doing the same to a pan of petrol was quite spectacular.

Perhaps we should all so some Citizen Science and take the max temperature in the engine room/compartment next year and see what range of temperatures we have. I'd be surprised if they are anywhere near the flash point. For those with the technology we could take the temperature of the engine hourly. I think my multimeter would do that, I'll check next time I am on the boat.
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I don't know the actual normal running temp of my diesel engine. A YGM 30 but I would not be surprised if it was over 60 c even if the compartment doesn't reach 60 c.
 
Sandy said:
No experience, but guess the source of ignition would be electrical. You can put a lit match on diesel and it won't ignite, so other flammable materials would be involved....
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Not true (40 years as a refinery engineer). It is a combustible liquid that is reasonably safe at ambient temperature in a tank, but...

1. A hot surface will create vapors. I've seen 3 explosions cause by welders. One caused a 100,000 liter tanks with 40,000 liters in it to jump 3 meters in the air. I witnessed two happen, was on the other side of the plant for the third. In one case the ignition source was grinding spark.

2. A mist will explode. I saw the aftermath of a mechanic sucking out a small tank with a common shop vac. It was bad.

3. Even a small amount of gasoline or additive can lower the flash point to ambient (0.5 - 2%). I did the investigation of an explosion that involved diesel with 1% gasoline added for winter service. The ignition source was static generated by the fluid flowing through a non-conductive hose (fuel hoses are conductive and include a ground wire that should be earthed at both ends). The suction pipe was PVC, which is an insulator (CPVC is more conductive.

(When I say conductive, I do NOT mean something you can detect with a common multi-meter. It is just enough to bleed off static and is on the order of megaohms.)

One fire generated by spontaneous combustion of oil soaked rags (no petrol, only diesel and lube).

Yes, electrical will do it. I saw a tanker burn to the ground after the battery cable chafed on the frame, next to a fuel line.

You do not need flammable materials and you do not need a match. However, the flash point (60C) is NOT the temperature of ignition; that is the auto-ignition temperature, which is similar for all fuels and is much higher. 60C is the temperature at which a vapor explosion is possible, if there is a tiny spark, and there are more spark sources than you think.
 
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I had a 1l automatic halon empty itself years ago.
The first I new about it was when I checked it at the end of the season! No idea if it was heat or simply vibration. The glass 'fuse' had gone.
I'd rather not have the same thing happen with a powder extinguisher.
 
Ruffles said:
I had a 1l automatic halon empty itself years ago.
The first I new about it was when I checked it at the end of the season! No idea if it was heat or simply vibration. The glass 'fuse' had gone.
I'd rather not have the same thing happen with a powder extinguisher.
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I had that happen years ago and this is why I now fit a fire detector and a remote operated fire extinguisher.
 
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