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Old 25-03-2015, 05:08   #1
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Location: land in Sydney, boat in Canaries and soon to cross via Cape Verde Islands
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Effective CO2 Extinguisher

I would like feedback on whether the idea below for a CO2 fire extinguisher installation would be effective. I got the idea from an installation on a Hallberg Rassey.

I have a Lagoon 400S2 and currently have 4 x 1kg powder extinguishers. If, however, there was a fire in my engine bay, I would not like to open the engine hatch and the plywood cover above the engine. That seems a bit scary. What I would like to do in this situation is, in order:

  1. Invoke a CO2 extinguisher set up to flood the engine compartment.
  2. Turn off the fuel supply. This is easy because there is a fuel cock on top of the fuel tank in the rear cabin.
  3. Turn off all batteries. This is easy to do too. The switches are in the rear cabins.
So the idea is to have a 5kg CO2 extinguisher installed in each rear cabin. Then route a delivery hose through the bulk head up high (there is already a hole there for fire fighting). The trumpet (or whatever it is called) would be directed at the engine. I could flood the compartment with CO2 without opening the engine hatch.



Do you think this would be effective? And is a 5kg extinguisher about the right size? I think it is the largest size in the portable extinguishers.



Thanks
Brian
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Old 25-03-2015, 05:28   #2
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Re: Effective CO2 Extinguisher

You can buy ready made automatic engine room fire extinguishers with electrical contacts to shut down the engine, etc. Check the West Marine catalog or website.


Much easier than building your own and the design has already been tested and approved.
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Old 25-03-2015, 06:01   #3
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Re: Effective CO2 Extinguisher

I agree, a pre designed system would probably be easier.

For your procedures your first step should be electrical isolation. No sense in killing the fuel and putting out the fire if your ignition source is still present.

My next comment is on your choice of extinguishing agents. CO2 smother's the fire by displacing the oxygen in the compartment. This means you need a relatively large volume of CO2 to effectively smother the fire.

If you go with something like FM200, you can save a ton of space because FM200 interferes with the chemical chain reaction that allows fire to exist. A much smaller volume of FM200 is required to acheive the same results. FM200 has the added bonus of not depleting your on board oxygen making it impossible to breath.

Something like the Sea-Fire fire stop can be used as a complete system to shut down electricity, fuel and ventilation, as well as discharge extinguishing agent automatically.

My boat is equipped with a much simpler old heat activated Halon (no longer commercially available) system. This system discharges extinguishing agent only- no automatic shut off. Newer systems similar to mine using FM200 are available for a reasonable cost from WM.

Sent from my SGH-I547C using Cruisers Sailing Forum mobile app
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Old 25-03-2015, 07:05   #4
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Re: Effective CO2 Extinguisher

The CO2 system you have envisioned will work OK. I don't know how large your engine space is, but a 5-kg (11-lb) CO2 would probably be big enough. You can also get 6.8-kg (15-lb) and 9-kg (20-lb) aluminum cylinder CO2 units.

Instead of trying to modify the discharge horn, they make a discharge nozzle for mounting in paint lockers and other enclosed spaces. A fire extinguisher service store should have them, or be able to get them for you.

A couple of other thoughts. With the proper plumbing and a 2-position valve, you could use a single CO2 tank to protect the 2 spaces. You would have to move the selector valve handle to the correct engineroom space (the one with the fire!) before discharging. You can then mount the tank in a central location (main salon?) that is a safe distance away from the smoke and possible flames.

You could also use an aluminum C02 tank with a "twist to open" valve as used for beer kegs, paint guns, etc. This has the advantage that you can just open the valve and walk away and the cylinder will discharge all of the CO2 without you having to hold a valve open. In the old days CO2 extinguishers use to have a metal clip that you could flip that would hold the handles together to allow for a "hands free discharge".

These types of systems are "manual", not fully automatic, and someone must be onboard to activate them.

Check with the people at SOTEC. They are a world wide fire protection company that are used to making up special extinguishing systems. There are lots of different ways to do what you want to do.

In the end, it may just be cheaper to install one of the pre-engineered fully automatic systems that are sold at marine stores. They will definitely be faster to install.
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Old 25-03-2015, 07:23   #5
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Re: Effective CO2 Extinguisher

Thanks for your comments to date. It makes sense to isolate the batteries first and it can be done very quickly. Thanks for that advice.

I don't mind the system not being automatic. I realize that nothing will happen if I am not on the boat. However I would be fine.

Cost is an issue for me. The automated systems that I have looked at are a lot more expensive than a standard portable CO2 extinguisher.

Brian
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Old 25-03-2015, 08:26   #6
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Re: Effective CO2 Extinguisher

Quote:
Originally Posted by FamilyVan View Post
I agree, a pre designed system would probably be easier.

For your procedures your first step should be electrical isolation. No sense in killing the fuel and putting out the fire if your ignition source is still present.

My next comment is on your choice of extinguishing agents. CO2 smother's the fire by displacing the oxygen in the compartment. This means you need a relatively large volume of CO2 to effectively smother the fire.

If you go with something like FM200, you can save a ton of space because FM200 interferes with the chemical chain reaction that allows fire to exist. A much smaller volume of FM200 is required to acheive the same results. FM200 has the added bonus of not depleting your on board oxygen making it impossible to breath.

Something like the Sea-Fire fire stop can be used as a complete system to shut down electricity, fuel and ventilation, as well as discharge extinguishing agent automatically.

My boat is equipped with a much simpler old heat activated Halon (no longer commercially available) system. This system discharges extinguishing agent only- no automatic shut off. Newer systems similar to mine using FM200 are available for a reasonable cost from WM.

Sent from my SGH-I547C using Cruisers Sailing Forum mobile app
Halon is good stuff and leaves no mess. CO2 is ok but really needs to be directed to the base of the fire. My wife has a fire protection business and they reclaim the Halon. we use it in our boat as well. Haven't needed it yet fortunately but once on our Catalina 30 we had a fire in our alcohol stove/oven cooking chicken. Halon put it out and the chicken was still good.
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