Automatic Fire Extinguisher

richardbayle

richardbayle

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www.richardbayle.com
I have a Beneteau 323 and I would like to fit an automatic fire extinguisher in the engine room, well cupboard really. I do not want dry powder, the ones I have found are a little bigger than is needed and there's not a lot of room to house one, anyone help?
 
It's usually possible to mount an automatic extinguisher horizontally on the ceiling of the engine compartment, so there should be room for one in your boat. However, gas suppressant extinguishers normally require the diesel engine to be fitted with an automatic shutdown system, so correct installation starts to get rather expensive.
 
[ QUOTE ]
Most halon replacments do not require auto shutdown. however are still a little expencive

[/ QUOTE ]Sea-fire, one of the most popular makers of small automatic gas suppressant extinguishers, say on their website “All diesel engine applications should install an automatic engine shut-down system.”
 
“All diesel engine applications should install an automatic engine shut-down system.”

and thats a very good reason not to ever buy a boat or system from them- auto shut-down is a great idea for generators and a disaster waiting to happen on propulsion engines.
 
[ QUOTE ]
“All diesel engine applications should install an automatic engine shut-down system.”

and thats a very good reason not to ever buy a boat or system from them- auto shut-down is a great idea for generators and a disaster waiting to happen on propulsion engines.

[/ QUOTE ]Well, leaving aside the fact that they don't sell boats, the theory seems to be that having the engine running will steadily suck the fire-suppressing gas out of the engine compartment. I'd imagine this effect would be more significant in a small compartment.
 
The fire suppressing gas by definition will stop the engine- but unless you have shut all air vents to the engineroom, any fire will probably re-ignite a short time later. All commercial vessels will have the ability to close engineroom vents, but very few pleasure boats are equipped with this.
There are of course a limitless number of potential scenarios for fire on board, but heres one- 20 metres off the dock, and the fire starts, alarm sounds, and your engine management computer decides to shut down the engine- you are left to drift out to sea.....

"buy a boat or system from them"
ok, don't buy a boat with their system fitted!

The bottom line is the skipper has to make the decision on the day when to shut down the engine- another example- new mitsibushi marine diesels, sold for propulsion, will shut down and not restart until the fault has been cleared, for an overheating alarm!
Apologies for the thread drift, Sailing Poodles!
 
Why is that, then? It seems eminently sensible to not have the engine suck in all the extinguishant and squirt it out of the exhaust. Automatic engine shutdown seems to be the recommendation of ABYC and the US coastguard, other than in small engine compartments where a manual extinguisher can be used.
 
[ QUOTE ]
The fire suppressing gas by definition will stop the engine....

[/ QUOTE ]Sadly, that's not true either. It's even possible for a diesel engine to run using gas suppressant as fuel. In any case, for it to work properly, the concentration of gas suppressant needs to be maintained, and a running engine will deplete it quite quickly. There's an interesting article here.
 
You don't seem to be alone in missing the point that the fire suppressant will suppress the fire IN your engine too - ie it will stop the engine- if the air intake is inside the engine compartment.
 
I stand corrected on the new exotic fire supressants- good old CO2 would stop the engines!
The point about the ability to close air vents stands though, and I just have a long standing problem about anything that can decide to stop the main engines without consulting me first!
 
I find this difficult to beleive or understand - see data sheet Here
Possibly they mean that if you do not have sufficient concentration of suppressant then the engine will be able to induce out enough to make the system useless?
 
Well, not according to all the sites I have looked at in the past 30 minutes or so. There is loads of information out there, from cruising sites, insurance companies, fire and safety organisations, coast guard, etc. etc. to show that the engine does NOT stop. Extinguishant can be depleted and air in the engine compartment replenished, leading to an increase of fire severity.
 
"air in the engine compartment replenished"

... so you must be able to close the air vents, or its just a matter of time before the fire MIGHT restart...

apologies again to the OP!
 
[ QUOTE ]
I find this difficult to believe or understand. Do they mean that if you do not have sufficient concentration of suppressant then the engine WILL NOT BE ABLE TO INDUCE OUT ENOUGH to make the system useless?

[/ QUOTE ]

Coo, am lorst already!
 
Or shut down the engine!

I suppose it depends upon what is burning, hot surfaces that could ignite fuel, whether engine compartment is open to bilges, probably lots of other factors.

That's where foam and Halon (yes, I know we aren't allowed to have it any more) excel, as compared with CO2 and powder. With the former two, once it's out, it's out. I don't know enough about the halon replacements to say, as my time as a fire warden ended before they were introduced.
 
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