Do dry powder extinguishers wreck engines?

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burgundyben

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If an automatic dry powder extinguisher goes off in your engine room will the dry powder get sucked in and wreck the engine?

Assume that the intakes have a very coarse mesh, holes around 2 mm diameter.
 
Ideally you'll know when the engine is on fire, and cut the fuel off, stopping the engines, so if the extinguisher goes off with stopped engines you'll just be cleaning to outside for weeks, as the power corrods like crazy!

If it goes off while the engine is still turning over, then budget to take the thing apart to get it out... otherwise it will be a pile of trouble waiting to happen /forums/images/graemlins/wink.gif
 
Theres a lot of anecdotal evidence (rumour) to suggest it does, but I've never seen it happen and doubt it does, unless you get a lot of powder in there. Good air filters should stop most if not all of it, ie, smaller then 2mm!!
There is a type of powder, which melts with heat, to flow over the burning area, after the flames have been extinguished, to form a film over the embers to prevent re-ignition, that may well do a lot of harm to the internals of an engine, if it gets in there. But I do not know what its called and also dont know if it's in normal dry powder extinguishers.
The powder we used to practice with was bi-carbonate of soda, which puts out fires very well.
But I have halon replacement types in my engine space, dont want to risk it with dry powder, as my air filters are like yours, plus the Halon replacement ones are far superior for engine spaces.
 
Well the reason I ask is about 6 miles from Weymouth on Saturday, bimbling along at 20 knots and a very loud pop and huge whoosh! One had gone off, no apparent fire so we let CG know and carried on.

There did not seem to be any effect on the engines and they brought us home in good time.

I think I may have dispelled an urban myth!
 
Yes they do, and I know because it has happened to me!

Ok, I don't have the sort of massive engine(s) most of you guys have - it's only 20hp in a sailing boat - but when we were anchoring in Ila Santiago in the Cape Verdes about three years ago, the blasted powder auto-extinguisher in the engine compartment went off. I've still no idea why as there was no fire or even over-heating, but off it went.

Initially I was more concerned about the HUGE mess it caused and the enormous amount of time it took to clear up even the visible stuff - we were still finding the stuff, which seems finer than talcum powder, months later.

However, the real damage didn't become apparent until a couple of days later when the engine took simply ages to start - very unusual, but there was virtually no compression. To cut a five day 'at anchor' saga short, after checking the valves (head off etc - all ok) I had to remove the engine onto the saloon floor, invert it, strip it down to remove the pistons where, as I suspected, we found the rings jammed solid in their grooves by burnt powder.

As the engine had only been operating at tickover when we were anchoring, and then only for no more than a few minutes, we were staggered at the ammount the engine had ingested. We got it all sorted out, but it was damned hard work, in a third world country, even with an engine weighing 'only' 4cwt, so Lord knows how you guys would get on.

To summarise, and as I have preached on the PBO forum many times, only a fool or a wealthy man would even consider a powder system in their engine room. In my opinion it is bordering on the criminal to even advertise them for such use. I have since, of course, changed to the Halon replacement stuff.

I VERY strongly advise others to do the same, or be pretty competent, well equipped or wealthy mariners!!!!
 
Jerry, thanks for that, interesting how it affected your engine, mine ran fine the following day for a couple of hours and restarted again later when I ran to warm them up to dry off the water after I hosed them down.

I'm popping down to the boat tonight, I'll run them up.
 
Yikes !

I covered about 14000 NM bouncing around at 25 knots with two of these above my engines.

Apart from the two reports above I have only herd of one other powder Fire Extinguisher going off, as far as I know it was hovered up and that was it.

I have been told by an expert if Halon go off, you need to change the Oil asap.

If you want to change your mind Ben after reading Jerry's post, you are more than welcome to do so, just PM me and I will return your cheque.

Cheers
Pete
 
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I'm popping down to the boat tonight, I'll run them up.

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Perhaps an oil and filter change + air filter prior to start up may be prudent, due at the end of season anyway ?????
 
I asked my insurance company about this a while ago, and their response was that if you had a fire on board, the extent of the damage would most likely be great enough not to worry about engine damage so they were happy to issue cover with dry powder extinguishers. We got FM200 in the end, and having read about extinguishers going off for no reason, I'm glad we did...
 
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Air filter? We're talking a perforated metal sheet!



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My Cumins have a perforated metal cylinder, which then has a 1 inch washable foam filter around it.

Could someone have disguarded your foam ?
 
If I had dry powder in my engine room I would have foam filters. But I havent I've got halon replacement stuff.
 
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