other considerations for fire detection - I work in the aviation industry, quite a few aircraft are fitted with a special kind of wire (we call them fire wire sensors) and a fire amplifier - if any point on the wire gets above a certain threshold, the amplifier triggers the alarm (can also be rigged to cut fuel, electric
and fire the extinguishers) if the "average temperature" of the wire gets above a (much lower) threshold, the amplifier triggers the alarm (usually leaving the aircrew with the choice of action to take, but can be rigged as before)
another extinguisher option I've just become aware about is called the "elide fire ball" - its a self contained, self triggering device, about the size of a cantaloupe - filled with dry chemical.
there are a number of differing types of handheld extinguishers available, they are all good for different types of fire, with "AB(E) dry chemical" tending to be the most versatile - it works in 2 ways, one, it seperates the fuel from the air with a blanket of powder, but two (and more importantly) it attacks the chemistry of the fire..... much older types of dry chemical dont have the second action.... also, some types of dry chemical can harden in the bottom of the extinguisher if left to sit for long periods, so give them all a jolly good shake every month or so...
I have used hand held extinguishers "in anger" 3 times..... what I can tell you is this - they DO NOT, on their own, extinguish a fire totally. depending on where you are, and how big the fire is before you get the extinguisher to it, they are best used to knock the fire back enough to evacuate. (in one case -fire in a bed
in an accommodation building- (2x 1.5Kg DCP bottles used), it knocked the fire down enough, we evacuated the building, called fireies...they arrived in under 2 minutes and finished the job (with large amounts of water))(second case -later turned out to be attempted murder by fire, idiot scored an own goal, I saved him and his partner and most of the house - (1x 1.5Kg DCP) the fire was large amounts of accelerant spread throughout the house, DCP knocked out about 80% of the flames.... fireies came and finished the job... with large amounts of water...)(third time, trailer boat with a fuel leak (1x 1lb DCP) knocked out the fire totally (was a very small fire as I got to it extremely fast), dumbass complained about the white powdery mess I'd made, re started his engine (complete with fuel leak) and drove off down the river......
when I bought a new boat, I took the 3 DCP extinguishers out of the old one and for a confidence test (3x 1lb units) ages 3 5 and 15 years, all showed green on the pressure guages. ALL FAILED the three year old unit spat maybe 1/4 of its contents a short distance, the 5 year old one shot maybe a teaspoonful a few inches, the 15 year one did absolutely nothing - was after this I learned about the different types of powder and to give them all a jolly good shake every month or so, and to replace (or at least have professionally serviced) every few years.
on your boat, have a very good critical think about how many extinguishers you need, and where they will be mounted.... my latest boat (only a few weeks ago) came with the only handheld extinguisher mounted in a cupboard under the sink.... most likely origin of a fire will be the spirit burner stove (between where the exit door is and where the extinguisher is mounted...) so, IMNSHO, whoever mounted the extinguisher is an idiot - if a fire starts, you have to go past it to get the extinguisher... I'm going to move it to the wall next to the companionway hatch
, and I'm going to mount a number more up in the cockpit
- in plain sight. first thoughts from the admiral - that wont look nice. after explaining the above, she has accepted my plan. PLEASE, do not let aesthetics rule
over functionality of emergency equipment