Dry powder fire extinguishers going off

[asteven221]

On my return today after a fine weekends cruising without any problems, I lifted the engine hatch to everything covered in a grey powder. I didn't have time to investigate it fully but I will tomorrow. Has anyone every heard of auto fire extinguishers going off by themselves? Certainly there was no evidence of a fire although I don't suppose it can be ruled out just yet. I've got one over each engine and as far as I can tell, only one has gone off. I will have to clean up the mess and I guess replace the air filters as a precaution. Does anyone know if there are any other precautions I should take to make sure everything is okay engine wise? Also, what is the powder i.e. is it safe to clean up or should I wear a survival suit? Any advice given will be very much appreciated. Thanks.

 

[Talbot]

Even more important than cleaning up thoroughly is the question of why you didnt know that the extinguisher had discharged - is there no audible warning system, what will happen if you had a real fire , and were not aware of it.

 

[jerryat]

Hi,

I hope your problem is ONLY the cleaning up. We had an automatic powder extinguisher discharge when in the Cape Verdes, without warning, and with no fire or over-heating. It took about 5-6 hours of very hard work to clear up, partly because it had got virtually everywhere, and because the powder was so fine that it passed through the vacuum cleaner bag, so ruling out that method.

In the end, I used a dustpan and brush, VERY gently sweeping it up and dumping it o/b. We were still finding the odd patch of the stuff weeks later.

BUT, that was by far the easiest part. Our engine was running on tickover when the damned thing went off as we were (fortunately) anchoring. To cut a long and very difficult story short, the powder was ingested by the engine which seized up the piston rings and left us with no compression and so, of course, no engine!

We didn't realise this huge problem until after the second day, when starting the engine for a battery charge, when it took quite a few more seconds to start than normal. Puzzled, I turned it off after a couple of minutes, then started it again after much trouble.

The third time - no chance, nothing would make it start, and then followed 5 days of incredibly difficult work, removing the engine onto the saloon floor, stripping it down, releasing the piston rings which were seized solid in their grooves, and re-building. All this done in a fourth world situation and at anchor in a swell!!

IMHO, and as I've preached on these forums several times before, dry powder extinguishers should NEVER be used in an engine room and should NEVER be advertised as suitable for such positions! Yet you'll still see so-called responsible chandleries still doing precisely that.

I really hope you're engne(s) are ok, but do check things out very carefully before venturing too far. It is highly unlikely that the filters will have stopped any powder entering the engine if they were running when it discharged, but that depends to some extent on how large the extinguisher was, how close to the engine and how fine the filter(s) is.

In our case, we had a 1.5kg unit in a relatively small engine compartment, so the concentration was fairly high.

To all Forumites who have these things installed, or are contemplating doing so, I urge you to consider changing to the Halon replacement type so that, whatever other damage may be done, at least the chance of powder damage is reduced or eliminated.

Cheers Jerry

 

[[2068]]

Umm, I think Halon extinguishers were banned around 2003 unless on aircraft or the military (or the channel tunnel). FM200 (HFC-227ea) is a substitute...

dv.

 

[asteven221]

Your point regarding an audible warning is cewrtainly very valid. It certainly make you think about these ethings when something like this happems. I am not sure if audible warning system are fitted on any boats as far as I know, other than the biggest of boats and proabably the newest of boats. I can't recall anyone every mentioning an audible system in any of the conversations I have had with other motor boat owners. Our boat has an exhaust alarm, fire blanklets, extinguishers and of course the engine bay auto extinguishers. An audible system is definately something I will look into fitting as I can see the potential for disaster without it.

 

[asteven221]

That's a scary story Jerry! That must have been a nightmare for you and I can only imagine the horror if trying to fix an engine in such circumstances. From what you have said the fact that your engines got progressively worse until the broke down completely is a concern. I will go down to the boat tonight to examin the whole area for fire evidence or any other causes. If nothing is untoward, I will start the clean up process and get the oil and filters changed at the very least. Other than that I don't suppose there is much else anyone can do other than keep an eye on it over the next few hours use. You mentioned yours went off whilst anchoring at tickover. I have not got a clue when my extinguisher went off and I just completed two journeys (there and back, funnily enough!) of two hours each way travelling at an average of about 15 knots. The engines are 306hp volvo turbo diesels so I imagine that there would be a a lot of sucking going on in the engine bay, so I assume that the engines must have digested significant amounbts of the powder. Out of interest why do you think the powder caused so much damage to your engine? If it's really fine would it not go through the engine oil undetected or is it a case of the stuff infects the oil and gums up or something like that? Am I correct to say that the powder isn't toxic and can be cleaned without worrying about getting horrible diseases... or should I wear some protection just in case? I hope your boats going fine now and that your enjoying some trouble free cruising. You deserve that after your troubles! Thanks. Once I get a picture of what happened tonight I will post my findings as it might help other in avoiding the same thing.

 

[ccscott49]

He said halon replacement, these are similar to halon, but without the ozone layer damage, exactly what I am fitting to my engine room, but of course they are very expensive (profiteering again) because we have to have them. Never use a powder extinguisher on an engine fire when the engine is running, unless you have no other choice, it's death to engines!! Messy stuff at the best of times! The powder is benign, so you dont need protective gear, apart from a face mask, any powder in the lungs is not a good thing.

 

[jerryat]

Yep, to the best of my knowledge Scotty is correct re the benign nature of the powder, however, as soon as you even look at it, the damned stuff billows up just like steam, and is a real bas***d to remove completely, so do use a mask.

I know ours only went off as we anchored and was therefore 'only' for a short time, so I'm not sure the fitting of an alarm would have saved the situation. I mean, we DIDN'T have a fire, or even any over-heating, the blasted thing just decided to go off!!

The powder didn't get into the oil. What appears to have happened is that it was ingested with the air to the cylinder. On the firing stroke, the mixture fired, but also 'pushed' some of the powder down onto the top piston ring. That then seized up, allowing the next ring to be affected and so on until virtually ALL compression had gone. I mean really gone! I could easily turn the engine over by hand with the compression levers off.

Let me clarify one point, my engine is only a 20hp Bukh diesel in a 32 foot sailing boat, not one of you MoBo's massive twin engine set-ups. I mention this, because you guys often have engine room blowers/extractors and things don't you, so there is a good possiblilty that this may have reduced the amount of powder actually ingested.

On a similar brighter note, your air filters may well be MUCH finer than ours (which is very coarse) so again, the prevention may well have been there.

If may offer one bit of advice. Do NOT start your engine(s) until you have removed every single bit of the powder, and that'll take a long time in our experience. Obviously you'll change the filters etc. That way you'll prevent ant further risk of damage.

I sincerely hope all will be well for you, but do let us know how things go.

Cheers Jerry

 

[zeros]

If an automatic dry powder goes off you may not notice until you look down below at the engines but if a halon or similar goes off how do you know??
How many people actually check there extinguishers regulary?

 

[jerryat]

Hi zeros!

I agree, you can't tell, but then neither the halon replacement nor carbon dioxide types do any damage to the engine, so to some extent, it doesn't matter. Ok, a faulty discharge will cost you a few squid to replace, but that'll be absolute peanuts compared to an engine rebuild or far, far worse.

My concern with dry powder units in the engine room is that, sooner or later, one is going to go off, stop someone's engine and cause what may end up as a fatal accident.

I don't see how you CAN check automatic extinguishers. After all, unless there is a way of measuring the temperature at which YOUR glass phial's GOING to shatter, what can you do?!

To me the solution is simple - don't use the powder type anywhere near your engine. As always, it's one's personal choice, but I've been there, had the major problems, and am definitely NOT going there again!!

Cheers

 

[enterprise]

The powder I believe is "Bakeing Soda" & the easiest way of getting shot of it is to wash out the engine bay.

No damage to environment & lot less hassle to yourself.

If you want to collect it use a "Vax" vacume after washing to the bilge.

Obviously a full can of WD for the engine after washing it would be a good idea.

Change air filters as mentioned in previous posts.

FM200 replaced Halon, they are expensive but sometimes turn up on EBay (where I Bought mine).

SEAFIRE offer various sizes to cater for all craft & have the facillity to give remote warning of activation & current state of charge.

 

[foxgoose]

Oh Sh*t

Having just spent a couple of hours in the engine room in 36deg and no shade fitting two bloody dry powder auto jobs (the only type I could find in Gozo) - I've now read the above and spent another half hour stripping them out and chucking them away!

As a matter of interest- how many people generally use auto dry powder in engine rooms and has anyone any idea what the failure mode is when they discharge accidentally?

Does the little capsule melt or shatter?

Is this a common failure or a once in a lifetime job?

I s'pose if it buggers the engines - once a lifetime would be too often.

 

[ccscott49]

Sorry, dont know how often they go off, but as you say once is enough, I still have halon in my engine room, but about to replace them with the halon replacement, I will leave the halons in there until the pressure gauges show they are duff! It's difficuklt to dispose of halon down here in Spain. They are not quite at the fridge recycle stage yet. I also have a few more nadheld Halons and will keep those until I find somewhere to dispose of them correctly.

 

[Dave_Snelson]

Struth!!! - I\'m getting rid of mine

Thanks for the advice jerryat. There is no way that I could lift out 2 x 4.3L V6's to rid them of powder. I had never heard of one of these things going off accidentaly before. /forums/images/graemlins/shocked.gif

 

[zeros]

[ QUOTE ]
Hi zeros!

I agree, you can't tell, but then neither the halon replacement nor carbon dioxide types do any damage to the engine, so to some extent, it doesn't matter. Ok, a faulty discharge will cost you a few squid to replace, but that'll be absolute peanuts compared to an engine rebuild or far, far worse.



[/ QUOTE ]

Sorry, my point was once it has gone off you can't tell - no visible signs- without actually checking the canisters and consequently when 'god forbid' you actually need it they are empty.

 

[jerryat]

Hi zeros,

Oh, I see what you mean. Yes I agree. The ONLY reason we changed the auto-halon we'd had for years was because, during the winter lay-up, I'd unclipped it to check something -- and realised it was empty!!!! As you say, nothing to show that, so weighing them occasionally is probably the best way.

I didn't want a dry powder replacement but the halon-replacement type weren't available then, so we bought two DP's. It was one of those that discharged causing all the problems. Still got the other brand new one!!!!

Cheers Jerry

 

[ccscott49]

You should check your extiguishers everytime you check your oil water, engine room checks. Which you do everytime you go out, dont you???

 

[asteven221]

Thanks for the info everyone. I went on holiday to Spain just after making the original posting. I got down to ther boat and dismantled the saloon floor to see the damage. One extinguisher has gone off and in the main covered the starboard side of the engine bay. I started to hoover it all up which for the big bits is fairly easy, but getting everything out between all the nooks and crannies is much more difficult. I will do that when I get back. I loosened an air filter cover (there are 4) and found evidence of the powder there but it doesn't seem too bad. A Volvo dealer suggested removing the housing to see evidence of what has got past the filters. I think I know the cause of the extingiusher going off. The exhaust elbow bend cracked and although it wasn't broken off completeley, it is about 10 inches from the extinguisher. I can only assume that more heat than usual was in the engine bay than normal around the extinguisher hence boom! At 650 plus vat for a bend I will try and get it fixed!! Money is about to run out so I will update the forum when I get back.

 

[asteven221]

Having returned from holiday I have cleared up the mess and washed down the engines. Everything appears fine and from what I can tell after inspecting the filters no powder seems to have got passed and into the engines. From my investigation it would appear that if you aim the extinguishers away from the air intakes then it will minimise the exposure to engine contamination. Obviously that has to be balanced with getting the powder to the best place if a fire breaks out. I discussed this whole issue with our local chandlers who seem quite knowledgeable about this issue. They told me that they have had dry powder extinguishers going off whilst sitting on the shelf. Seriously! These things going off does not seem uncommon. Another person told me that they had one in an office that went off for no reason and just last night I heard of a boat being towed into a Clyde marina within the last weak due to engine damage caused by a dry powder extinguisher. I have not had confirmation about this incident, but I was told that their was £12k of damage! Ouch! As soon as I get confirmation of the details I will let everyone know as it would appear that this is a more serious issue than simply an isolated incident. I priced a halon replacement at £300 which a bit steep. Has anyone thought about contacting their insurance people to see if we are covered if the engine gets wrecked. I suspect thet will just say fit halon replacement extinguishers if your concerned about dry powder. Fortunately I seem to have got off lightly with this incident and if I hear anything that I think is worth posting, I will post it for the benefit of everyone.