Engine compartment fire alarm

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Miker

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I raised the question of fire extinguishers on a previous thread. Has anyone any views on the most suitable fire alarm for the engine compartment with an automatic halon replacement extinguisher fitted? Would a bog standard smoke alarm suffice?
 
Would you hear it above the engine/boat noise?

Would think in an engine space that a heat detector designed for the specific area of risk would be better.

Maybe try contacting someone like (?) SeaFire for advice.

PW
 
Miker - pilotwolf is absolutely correct and without doubt the only fire detection device appropriate for your engine bay is a heat detector. Ideally a fixed temperature device at least 20 degrees C warmer than the hottest temperature you are ever likely to achieve under stable operating conditions in the location selected. You may also consider one which is a combined rate-of-rise unit too. These units as fitted to commercial fire alarm systems (of the conventional variety) are simple bimetallic units leaving the connectors provided as simple switches. You could incorporate these into any circuit that you choose to create at 12 or 24Vdc thus enabling you to operate a remote light or sounder unit without any form of complex control panel.
 
I am going to try a standard smoke alarm on the basis that there is no smoke without fire.
To get over the noise factor, I will fit the alarm outside the engine compartment, but detach the sensor and fit it on an extended wire inside the compartment.
If this works, it will be a very cheap solution to fire detection and will mean that in the event of an alarm, I can cut the engine before using a hand held powder extinguisher.
 
Thanks everyone. A heat detector sounds better. I agree "No smoke withoit fire" but can you have "Fire without Smoke"? I take the point about being able to hear the aural warning.
 
Chrisr - good luck my friend. 12 years in the fire detection and extinguishing industry says ya gonna have plenty of heartache ahead of you. Oh and the correct device might cost you IRO £30 that's all........ /forums/images/graemlins/confused.gif
 
Re:WAIT just a minute

i was one of those who raised the issue of an alarm in engineroom.

The point of the alarm is that if you're down there and the auto system goes off then you may not even make it out of the engineroom- cos of the auto gas stuff asphyxiating you.

Hence the alarm (or at least, an important alarm perhas THE MOST IMPORTANT alarm) must be part of the same system that sets off the automatic system and warns "auto system about to set off- everyone out now! "

Otherwise, with a sepret smoke alarm, you mite heyho nip down to investigate only praps to be whacked by the autosystem as soon as you arrived?
 
How does the Halon replacement compare with the performance of the BCF we used to have? I was going to fit CO2 with bottle, valve and delivery pipe til it was pointed out that the gas would freeze in the pipe, so in limbo at the moment. Atomized water spray only.
 
Large ships engine rooms and machinery spaces have been protected by CO2 for over fifty years now and freezing up of the CO2 within the pipes has not presented a problem. You will see freezing up on the outside of the pipes in humid conditions but this will not hamper the operation of the system. CO2 is most definitely an option for you however you will need much more CO2 than Halon or even it's latest near equivalent - FM200. This quantity often makes it inhibitive in a pleasure boat. The CO2 system will ideally be connected to pipework terminating in at least one 4 port nozzle.

Fine water mist is an option.

TCM - indeed care must be taken with ALL gaseous extinguishing systems and the British Standards together with the DOT code of practice very clearly sets out safeguards for just this event. Systems vary from having a predetermined time period during which the pre-emtive alarm will sound through to a method of isolation of the system prior to entering the space. Be very careful guys.

Since I'm rattling out a lengthy reply here, here's a little more for Chrisr on the subject of smoke alarms. Smoke alarms do not always need visible particles to set them off and often a hot "smell" as a result of free radicles will trigger them. Indeed the more sensetive ionising radiation sensors will often be triggered by hot gasses, just as you may find in abundance within your engine compartment. Optical detectors will require obscuration of the sensors to trigger them off. The only sensible choice for your average small boat compartment is heat. Now if you have a very large engine room within which you can walk around freely with standing headroom then you may get along with smoke detection but if your engine room is THAT big then I suggest you wouldn't be tight @arsed enough to look at the route you are! (No offence intended).
 
I'm thinking KISS: suitable sized CO2/fm200 bottle in a cabinet on the wheelhouse back with a handwheel valve and pipe, about three metres. No alarms, and no engine damage from foam/powder/water ingestion. We had cable operated BCF and the cables were bad for seizing up through lack of use.
 
It seems that there are two issues.
- The automatic goes off during the night when there is no fire. What are the chances of that and would an LPG detector sound an alarm as the gas seeps out of the engine bay?
- The automatic goes off when there is a fire. A heat detector connected to an external alarm would sound, but all the ones that I have found on the WEB go off at 54 - 62 degrees C. I am wondering whether under normal running the heat emitted from the engine would trigger off the alarm. But I would have thought that I could site the detector in a suitable position. Trial and Error?
Has anyone any recommendations on a suitable heat detector?
 
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