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Old 11 August 2006, 18:05   #11
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Quote:
Originally Posted by codprawn
A console is a lot more enclosed than a car engine compartment with the bonnet up - Halon works fine - I have used it several times. Unlike CO2 it doesn't just smother - it actually interupts the combustion process. 1kg of Halon is equiv to 10kgs of CO2. You do NOT need to flood totally with Halon.
Both my (and I believe BogMonster's) consoles are alot smaller than a car engine bay with a lot less gubbins in there to (1) catch fire (2) get in the way of the extinguishant (I think I invented that word). Perhaps on the Codship you "need" Halon but not on ours. We also have (i believe) pretty basic electrics so I think an engine fire is much more likely.

Halon was banned for a reason (you might not agree with it - but get over it).

I don't think CO2 is a realistic proposition on an open boat (or possibly any boat as its an asphyxiant - so not ideal in an enclosed space). So you are looking at foam or powder. Both work. Both make a bloody mess. But burnt boats aren't too pretty either.
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Old 11 August 2006, 18:43   #12
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Stephen - does your fuel tank have a 'quick' disconnect fitting on it like connects the fuel line to your engine? almost as good as a stop cock.
dont disconnect at the engine end if its on fire-you could end up holding a burning fuel line when it spurts on disconnecting.
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Old 11 August 2006, 18:59   #13
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Originally Posted by wavelength
dont disconnect at the engine end if its on fire-you could end up holding a burning fuel line when it spurts on disconnecting.
Appologies if that is what you thought I was suggesting. I wasn't. If the engine is on fire then you wont find me trying to pull that tricky plug off the front. I was simply trying to describe the connector - as I don't know the correct name.
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Old 11 August 2006, 19:24   #14
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Stephen, I think your idea of using a central heating valve is a good one. Obviously, the sensing bulb would need to be where the fire is. In an open boat I guess you would need to give the valve a good coat of paint to protect it but, on my central heating, the capillary tube and the bulb are both copper so they would last a good while.

On my boat, I have a 2kg hand CO2 extighisher in the cabin and two of these under the engine hood. http://www.magicmarine.co.uk/fire/Ex...herOrders.html

I do believe the CO2 is useful. If the fire is large enough I feel you are unlikely to win with any smallish hand held extinguisher. I know CO2 is not recommended for materials that one might imagine may burn on a boat but I've used CO2 on smallish fires for which they are not recommended and the dousing was pretty well instant. In a fire situation that is recoverable, I'd expect the CO2 to cool it and I'd rather not have to clear up the mess of powder. In an engine compartment, filling your engine with dry powder while it is running with surely do damage.
I do think that if you get a real petrol fire it will simply be a whoomph and your best bet would be the sea, if you are able.

My understanding of C02 and Halon replacement is that they mainly work by absorbing the heat of the fire rather than by smothering it.
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Old 11 August 2006, 19:40   #15
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Halon and CO2 fire extinguishers work by removing oxygen from the local environment around the fire. They don`t cool the fire. Basically all fires have 3 ingredients, ignition source, fuel and oxygen. If you remove any ingredient you won't get a fire.

Codprawn, why the obsession with halon fire extinguishers ? Move with the times. The replacements 4 halon are just as good, if not better.

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Old 11 August 2006, 20:37   #16
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Quote:
Originally Posted by Polwart
Both my (and I believe BogMonster's) consoles are alot smaller than a car engine bay with a lot less gubbins in there to (1) catch fire (2) get in the way of the extinguishant (I think I invented that word). Perhaps on the Codship you "need" Halon but not on ours. We also have (i believe) pretty basic electrics so I think an engine fire is much more likely
Pretty much right - there is not a lot in mine really. If the whole thing goes boom then I guess I am swimming, but the real point of the exercise is that I'd hate to see it go up in smoke for the sake of a teeny little fire that could easily have been put out. Even if I lost the engine, if the rest of the boat was saved it would be worthwhile. Also, the sea isn't that hot here...
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Old 11 August 2006, 22:11   #17
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Quote:
Originally Posted by CJL

Codprawn, why the obsession with halon fire extinguishers ? Move with the times. The replacements 4 halon are just as good, if not better.

Chris
But that is the whole point - they are NOT better - or even as good for the purpose.

Or have Boeing and all other aircraft makers got it wrong? Halon is still exempt for critical use applications such as aircraft cargo holds etc.

http://www.fire.nist.gov/bfrlpubs/fire05/PDF/f05068.pdf

Many things that have been forced on us aren't always for the best.
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Old 12 August 2006, 05:23   #18
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Originally Posted by CJL
Halon and CO2 fire extinguishers work by removing oxygen from the local environment around the fire. They don`t cool the fire.
I think that is true for Co2 but at close quarters, as might be the case in a rib, the cooling effect is substantial and if you release Co2 into a small fire there is often ice on the surface where the flames have been extinguished. Whilst displacing the air (hence oxygen) is a benefit, if you do a bit of research on the Halon replacement gasses, I think you'll find they do absorb heat. If they just displaced the oxygen, it wouldn't matter which inert gas was used.

I would guess that they initially remove heat to below a point of ignition then they prevent reignition by hanging around excluding the oxygen. As I said, just guessing.
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Old 12 August 2006, 06:20   #19
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I'm a bit bored this morning so did a bit of googling for ya.
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Old 12 August 2006, 06:25   #20
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Anyway, I think Stephen's idea of shutting off the fuel supply to prevent a small fire turning into an inferno is cool. It could be especially effective for a diesel boat and it might not be long before a boat I know has a valve fitted.
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