Engine bay fire extinguisher

[JeremyF]

After hearing the mayday a couple of weeks ago for an overheating / smoking engine off Hamble Spit I finally got around to filling an automatic ABC fire extinguisher in the engine bay.

The spec sheet states that it goes off at 68 C. How hot does and engine bay get in a typical new noise-insulated engine bay? I'm just wondering what the margin is between long operation on a hot day, and the thing going off. To save me buying a gardener's min-max thermometer, has anyone worked this out?

Jeremy Flynn
Dawn Chorus

 

[steve_cronin]

The healthy operating temperature of marine diesel engines is between 83c and 88C. Electronic Overheat alarms are usually factory pre-set at 90C. These are of course the ENGINE temperatures, that is to say the temperature of the water in the cooling system. The engine bay temperature should be much lower that this but it depends where the sensor is located. When I open my boat's engine compartment after a few hours running in the Med it is like opening a furnace and I reckon that it is at least 55C in there. i would have thought that your 68c might be a little low but unless your dealer is going bankrupt from paying out on a lot of damage claims due to premature activation- yes I said ACTIVATION! - he probably knows the optimum figure.

Steve Cronin

 

[Chris_Robb]

Don like Automatic fire exstinguishers

I presume ABC is powder. So if powder goes off while the engine is running, it ingests the powder, and ok - no fire, but no engine also.

Far better to have a manual trigger so that you can stop the engine, and fire the exstiguisher.

I don't like the idea of Powder on an engine, as it congeals on every hot surface, which would include the alternator etc. It also requires very accurate direction, and will be useless if the fire is at the other end of the engine compartment.

I am sticking with Halon (manually triggered ) until I get caught. There does not appear to be any satisfactory replacement to the demise of Halon. CO2 requires some pretty large heavy cylinders to ensure enough supply.

 

[JeremyF]

Re: Don like Automatic fire exstinguishers

I'd love to get hold of Halon, but of course its gone now. ABC is a powder for a variety of fires including fuel.

The extinguisher was sold to me by Jimmy Green, and they state that they are designed for engine bay installations. But, 70 deg C does not seem that high.

Jeremy Flynn
Dawn Chorus

 

[Chris_Robb]

Re: Don like Automatic fire exstinguishers

Halon is still around unoffically - I bought 3 large exstinguishers all tested - for £20.00 - these were returned unit sfrom people changing types to comply. Do some ringing round the small specialists in your area.

All the chandleries seem to sell auto powders for engine rooms. I can't help feeling that its a wrong use. Yes it will put out a fire if directed strainght at the base, but how can you be sure where the fire will start when you set up a fixed unit.

My Halons all have a metre long hose on them, so that it can be poked in through the finger hole on the engine door. It is vital you don't open it up and feed the oxygen/air supply.

 

[steve_cronin]

I buy Halons....

... from a second hand office equipment shop. They have Co2's also all at £5 each. The latter are also useful, with my home made adaptor for blowing up an inflatable if I'm in a hurry or feeling lazy!

 

[Chris_Robb]

Re: you lazy b.........

Well why not!

 

[JeremyF]

Re: Don like Automatic fire exstinguishers

The one Ive got has a rotating spreader below the exit. I presume that if it goes off, the powder hits the spreader and it goes everywhere - a bit like a fertiliser spreader.

I'd prefer Halon manually pointed through the hole into the engine bay, but all my enquiries led me nowhere. Can you PM me with the name of your supplier, Chris?

Jeremy Flynn
Dawn Chorus

 

[Chris_Robb]

Re: Don like Automatic fire exstinguishers

My guy was a local Haslemere supplier - I checked with him - I cleaned his stock out - ring round some of the small people in yellow pages, you would be suprised how many there are.

 

[pandroid]

Re: Don like Automatic fire exstinguishers

This may be a daft question, but if you dont open up the engine bay, how are you supposed to know that its on fire? Smoke coming out the air intake?

 

[Chris_Robb]

Re: daft or draught!

er.... don't know - I have a standard house smoke detector in the engine room, - don't think I would hear it if it went off. Mounting just outside would be no good, as air is sucked into the engine compartment, So how would I know there is a fire - idunno....................

Well - I tell you when I have my first fire!

Lets have some ideas.

 

[duncan]

having a sonar transducer in the engine bay, admittedly on the floor, with it's built in temperature sensor accessing only the air I can tell you that it has seen 98, but that is in F !
This is a reasonably small engine bay, pretty full of 230hp Yanmar.
Hope this helps

 

[airbubble]

Almost all engine manufacturers want to have the ER temp below 60 degC.
Not only is it more dangerous, your engine's performance will decrease enormously when it has 60 deg or more to work in. I must admit that i find the setting of 68 to set the system of looks a bit sharp to me also.