CO2 fire extinguisher?

[sailak]

Originally Posted by MedSailor

Can you explain the differences in the mechanism of action further? I am especially interested in hearing more about the underlined section.

CO2 displaces the O2.

Halon and Dry Chemical interrupt the chemical chain reaction, they do not "blanket" the fire preventing O2 from getting to it -- common misconception. Instead they work at the molecular level to "turn the fire off".

It used to be called a "fire triangle" -- heat, fuel, oxygen. For many years now it has been the "fire tetrahedron" -- heat, fuel, oxygen, chemical chain reaction.

A quick link

[LinekinBayCD]

I thought Halon and now Halatron are preferred for engine compartments over CO2 because of the potential for thermal shock damage to the hot engine caused by the cold CO2.

I installed a fire port in the engine compartment to use with a Halatron extinguisher. I called the local Coast Guard Station in BBH Maine when investigating the correct type of extinguisher to use and was told that dry chemical extinguishers should be aimed at the base of the fire, impossible with a fire port.

[Brewgyver]

Originally Posted by downeast450

Brewgyver,

Ignition, as in starting a fire. Open sparking electric motor.

Thanks, Down, that's what I would have assumed. Hylyte was talking about having the blower(s) killed by an engine cutoff, wanted to be sure you weren't talking about that. Your existing blower most likely is ignition protected, even though it's not located in the engine compartment, many boats are set up this way. And most sailboats don't have continuous duty blowers, anyway, so wiring it to an emergency engine cutoff would just complicate matters unnecessarily.

[downeast450]

Brew,

You are probably right about the blower. It sits in an inconvenient place. I would rather it were out of the way as an in-line and there are much better places. Being able to shut it off during a fire is important. If I can find one that is quiet enough I might start running it whenever the engine is running. Either way I am going to move it. It currently makes a useful space under the quarter birth inconvenient.

Down

[svHyLyte]

Originally Posted by downeast450

Brew,

You are probably right about the blower. It sits in an inconvenient place. I would rather it were out of the way as an in-line and there are much better places. Being able to shut it off during a fire is important. If I can find one that is quiet enough I might start running it whenever the engine is running. Either way I am going to move it. It currently makes a useful space under the quarter birth inconvenient.

Down

Down--

In our case, our bilge blower runs continuously when the engine ignition is activated. The blower is mounted on the inside face of the transom, discharging through a clam-shell vent with a 3" vent tube positioned to the top of the engine compartment. Three 3" static tubes are connected to similar clam-shell vents in the transom and positioned to the bottom of the engine compartment to provide cool, fresh air to the engine compartment.

Our Bilge Blower

When our automatic fire extinguisher discharges, the activation trips a visual and audible alarm and a solenoid that shuts down the motor and the bilge blower.

Our fire extinguisher: Fireboy

If you will be dealing with an external (to the engine compartment) manually activated fire suppression system, all you'll need will be a temperature sensor in the engine compartment connected to an audible alarm/alarm warning light. You'll will need a "cable stop" for the engine, and an interrupter switch for the power circuit to the blower.

FWIW...

[chucklesR]

Just a side note on Co2 extinguishers - in the Navy we did a routine monthly weight check to make sure they were still full and ready for use.

They do leak, but the primary reason for the monthly check was to make sure sailors had not used them to cool off a six pack.

Downeast, I suggest you weigh yours and make sure it's full since it's been sitting in a shed. You should be able to find spec's for it on the manufactures web site.

[downeast450]

Chuckles,

Thanks, It is headed to the shop that fills and maintains fire equipment around here. It will be full.

Down

[downeast450]

FWIW,

Good advice and information. Keeping the bilge blower running makes sense to me.

Your summary of the situation is right on. It will be comforting to have done a few things as prep and prevention. The prospect of a fire is very disturbing. Knowing there are specific systems and procedures ready to help me deal with it is helpful.

Down

[hellosailor]

"Halon is no longer available due to its ozone depleting effects. "
AFAIK it is still being recycled from older equipment and available to refill older equipment--but more expensive because it is no longer being manufactured new.

The downside to Halon is that apparently once it combusts it becomes carcinogenic, so even though it is "breathable" the advice is if you've used it, get out until it has been exhausted. With CO2, you still need to get out to find air to breath but at least CO2 won't mutate you.

The dry powders typically are corrosive and they get into everything, but Kidde now sell a special "kitchen" extinguisher, the typical "liter bottle" size. It is unrated because it falls outside the rating tests, using a lower pressure and wider pattern with the intent of putting out kitchen oil fires in a way that spreads the burning oil less, and using baking soda instead of the conventional chemicals so it won't corrode metals and electrics. Something else to consider. Can't be rated or USCG approved (yet) but I sure like the concept of less damage and less cleanup.

[downeast450]

I will install a 20 pound CO2 bottle under the 1/4 birth, under a shelf that leaves an irregular space perfect to cradle the bottle. Moving the blower fan out of that space will give me all the room I need. CO2 it is!

Down