Gas alarm!! But no LPG leak.

Sans Bateau

Sans Bateau

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Motoring from Chichester to Newtown Creek on Saturday, wind bang on the nose and against the tide, 2500 revs and only making slow progress. After some time, past Cowes the gas alarm goes off. I go below, cooker is off, we have an electric solenoid which you activate to turn the gas on, this was off. I get down on all fours, sniffing the cabin floor, no smell of any gas, the alarm goes off on its own. Curious I think. It happens again and the third time, it does not reset, the gas was turned off at the bottle at the first alarm, so it must be a fault.

Later I go below and smell a curious smell, just like the mud at low water in Chi harbour??? Mmmm, strange. Batteries gassing? I check them, they are all cold, but the smell is defiantly in that area, I take a look at the battery meter, voltage is 15.6v!!! Is that right? The batteries have been charging for several hours, should the voltage be that high, does this mean there is a problem with the Advec controller?

But the interesting thing here, unless someone more knowledgeable tells me other wise, it seems that the gas alarm is also activated by the batteries gassing, if thats what it was. But is this gas heavier or lighter than atmosphere? If lighter, how did it get down to cabin floor level to set off the alarm, I could not smell it when having a sniff? Sorry, lots of questions.
 
The sensor elements do have some sensitivity to hydrogen, but as you say, it should rise.

The sensor elements can also fail over time with exposure to water/moisture [yes, not ideal for yots]. So it may just be a failure of this kind, rather than correlating with other events. One of my sensors went this way and had to be replaced. [See recent PBO about home-made detectors, the non-calibrated sensor elements themselves are only a few pounds on eBay]

I can't help you with the voltage levels, etc, but it sounds worth looking for some further advice about that.
 
15.6 definitely sounds too high to me. 14.8 is the most I've ever seen recommended, and I'd expect some gassing at that level.

Pete
 
15.6V is pretty high, I would not like to see that applied for long periods. I would check the Adverc manual.
It could also be rather high for other connected equipment.
Battery gas is hydrogen and oxygen, the hydrogen definitely rises, I think oxygen would be pretty neutral buoyancy.

Could the gas alarm have got splashed? Mine sometimes goes off when switched on after a period off, apparently it's dampness and you cancel it two or thre times giving it time to dry out.
 
I once had gas alarm going off. It was crud from the bilge decomposing - heavily used sail training yacht. Anyway, once it was cleaned out that was that. Your avatar suggests your not a manky bugger, so I would go for the batteries or duff sensor.

Batteries: I once had a battery boil dry and it was the smell that alerted me to it - rotting eggs, like H2S (hydrogen sulphide) smell, something I am very familiar with in my line on work. Anyway, I have no idea if H2S can be produced by really duff batteries but that gas is heavier than air and at very low levels you wont smell it either. Just a thought, it could be well wide of the mark.
 
galadriel said:
Batteries gassing? I check them, they are all cold, but the smell is defiantly in that area, I take a look at the battery meter, voltage is 15.6v!!! Is that right? The batteries have been charging for several hours, should the voltage be that high, does this mean there is a problem with the Advec controller?
Click to expand...

Is it possible that the Adverc's sensing lead has become disconnected? This will lead to excess charge voltage.
 
pvb said:
Is it possible that the Adverc's sensing lead has become disconnected? This will lead to excess charge voltage.
Click to expand...

TA, I'll check the manual for that.

In reply to others:

Pilot gas alarm is about 3 years old.
Sensor is at cabin sole level.
Batteries are also 3 - 4 years old, sealed.
There was no evidence of water on the cabin sole, although we had taken a fair amount of spray and some lumps of green over the spray hood, which Errr, gave SWMBO a bit of a soaking.
 
I fitted a new Pilot gas alarm with 2 sensors to my last boat. After 3 years it kept giving random alarms. By swapping sensor connections around I established one sensor was duff. Cost about 30 squids to replace.
 
A boat I was on had its gas alarm triggered by bananas becoming ripe. I kid you not. Don't know why.

I would not like my batteries to be charged at over 15V either.
 
sometime ago I discover that the use of sun blocker aerosol can trigger the gaz alarm;it took me a while to find the problem it was on a charter boat
 
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