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Fire Extinguisher Query

Dear Steve:

I recently looked at a new boat at a boat show.  I noticed something that caught my attention and I wondered if you could comment on it to let me know whether I should be concerned if I were to consider buying this boat.

There’s a large, permanent fire extinguisher in the engine compartment.  It has a wire attached to it and a pilot light at the dasboard.  Does this mean it can be discharged manually?  If it discharges will it shut down the engine automatically?

Tom from New York


This is a great question, thanks for sharing it with me and the other blog readers.

The fixed fire extingusiher you saw sounds as if it’s passive.  That is, it will discharge on its own when the temperature within the engine room reaches 175 F.  The wire simply completes a circuit that enables the pilot light, telling the operator that the system is charged and ready top use.  Unless you also saw a red T-shaped handle, it’s usually at the helm or outside the engine room door, that was attached to the fire extinguisher through a jacketed control cable, then no, the system probably cannot be discharged manually.  Which means, you would have to wait for the temperature to reach 175F before the system discharged itself.  Not necessarily a good thing.  There’s no way to know whether the system would also shut down the engine (and preferably the other “air breathing” equipment such as generators, blowers etc) unless you determined if it was equipped with a control relay that’s designed for this purpose.  It’s essentially a paperback book-sized black box with a number of wires attached to it.  This is a worthwhile function because, unless it’s installed, it’s possible for this equipment to consume and exhaust the fire extinguishing agent, thereby limiting its effectiveness and possibly preventing it from smothering the fire.  With the relay system, you don’t have to remember to shut anything off, the system does it all for you automatically.  By the way, if the pilot light is not on, then the system is either discharged, the circuit is not energized or there’s an electrical fualt in this circuit, all of which warrants immediate attention.



A manual T handle discharge along with the pilot light panel and override switch.

052706002reduce_1205892779 A manual T handle discharge along with the pilot light panel and override switch.

A manual T handle discharge along with the pilot light panel and override switch.