Pilot Mini Gas Alarm went off last night

[DavidJ]

I have a PILOT Mini gas alarm fitted to my S37 (in the med) and a couple of nights ago it went off 3 times. My gas is switched off, there is no smell or diesel in the bilge and fanning the sensor switched it off which indicates that it was picking up something and is not the cause of an electrical fault.
Last night it went off again.
I antisipate it doing the same tonight.
The nights are cool here now and there are mosqitoes so tend to sleep with all windows shut.
The sensor is placed just behind the AirCon inlet grill.
What can the sensor be picking up??

 

[dragoon]

Hi David,
I had a similar thing with our Plastimo alarm some time back. Suddenly it started going off after being on for 3 hours or so....this normally meant that it would go off in the early hours since the circuit would have been switched on after returning from the pub.

It took me quite some time to figure it out, but some oily bilge water had got onto the sensor, and since the sensor heats up whilst operating it would generate fumes that would then set itself off.

I "blew" the sensor out in the end to get rid of the offending substance. It's been okay since.

Hopefully that might give you some clues as to where your problem lies.

Cheers,
Paul

 

[DavidJ]

Thanks Paul
I'll try a good clean up before going to bed tonight and let you know (dependant on whether I can 'wag' onto this wifi connection again)
My sensor is quite warm also, but it's on all day not just at night.
Tomorrow I might move the sensor further away from the (generally damp with condensation) AC unit.

 

[nanofkyle]

Had the same problem with this equipment on a prolonged offshore passage. Reckoned it was sensitive to low battery voltage!

 

[DavidJ]

Thanks Ronald
I don't think it's that because other devices working from the same battery (toilet and bow thruster) are working full power. No repeat of problem last night. I repositioned the sensor this morning and noticed that when I blew gently into it, it set off the alarm. So is it responding to Carbon Dioxide?? I'm a non smoker so there's no CO in me.
If it responds to a concentration of Carbon Dioxide then maybe we were just deoxygenating ourselves overnight with all the windows closed !! although this is the first problem in over two years of fitting the gas alarm.
hmmmmm!
I have sent off a query to Technisol who make the Pilot Mini Alarm and will post their reply.

 

[ps1]

I've had the same problem, gets you out of bed fast when it goes off. Trying to turn it off when in a befuddled state is enlightening.
I believe the heads have a finite life so I replaced it, no problems since. Google for 'TGS 813, Conrads in Bedford' for suppliers.
Technical aspects web page

 

[Robin]

Ours has gone off in the past for fumes from contact adhesive, about 30 minutes after I fixed a bit of lining back, and for battery gassing when I turned the (then) manual charger rate up too high. Friends have had theirs go off for refrigerant gas loss, so if yours is near the aircon unit, could that be a culprit?

 

[pheran]

Chuck it over the side - lack of reliability means that most of them are worse than useless. Ours, when we had one, would be set off by all sorts of 'non-gas' things - including ripe blue cheese!

 

[Tim777]

Changed the sensor on mine after suffering two months of intermittant alarms with no apparant cause. I moved mine from under the cooker to the bottom of the door frame at the entrance to the Fwd cabin. Having installed it I tested it did go off if cooker was left on for 2 mins unlighted. No problems since. You must have one IMHO if you sleep on board and leave the gas on.

 

[pheran]

We had two sensor heads, one above floor, one beneath. I'm all for maximum safety where gas is concerned but felt that spurious alarms served only to frustrate this. So instead, we have adopted a regime where the gas is turned on only when an appliance is in use. Otherwise it is off, certainly when under way and always at night. To avoid any inconvenience, we had a extra isolator installed just outside the gas locker so its open a little trapdoor, flick a switch and its all done. And a bubble tester which is checked regulrly to ensure we are remain leak-free.

 

[SimonA]

Just turn off the gas at the bottle when you are finished with it and get a handheld detector to check the fittings once in a while. That's what I do. I have an electric fridge, obviously you can't do the above if you have a gas fridge.

 

[DavidJ]

Thanks for all your replies, it seems I'm not alone. Papa_Sierra, are the details you gave, for the Pilot Mini gas Alarm?
By the way, another good uninterrupted night last night after repositioning the sensor.

 

[ps1]

No, mine was a Plastimo gas alarm. The sensing head was a Figaro TGS 813 - yours may be the same. It is marked around the face on the head. I had thought of fitting a switch in the power supply line to the unit to give some respite from the screeching (not SWMBO) while the problem was located. Haven't.