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Lpg 'sniffer' alarms. Lifespan and effectiveness

magnetman

By magnetman
in Boat Equipment

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magnetman Veteran II

magnetman

Posted
Posted

Rather than hijack Blackrose's thread about CO alarms I thought a new one would be better :)

 

I have been considering getting an LPG alarm. I know its probably not actually needed as the LPG system is sound but I've noticed that a lot of barges for sale on european waterways have them. Not sure if its a regulation requirement or just 'good practice' but anyway.

 

What I am interested in is the life span of an lpg detector. There are fairly cheap and quite impressive looking units available on internet the auction / buy now site but I have a suspicion they may be basically useless. I don't actually know this though which is the reason I have chosen to start this thread about lpg sniffers.

 

Anyway

 

Any opinions on this thing would be most welcome. Anything funny anyone has to say or any 'poo-pooing' of the whole thing also more than welcome. ta

 

http://www.ebay.co.uk/itm/GAS-CO-LPG-DETECTOR-COMBINED-12V-230V-WITH-LCD-DISPLAY-/191449510001?pt=UK_Safety_Alarms&hash=item2c9347b071


In case you don't want to click the link it is an LPG alarm system with an LED digital readout and a CO alarm also built in. Its not dropshipped from China and its about 35 quid.

 

just wondering if its a bit old

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Detling Rising Star

Detling

Posted
Posted

Mine states life of 5 years in the manual, It's to do with the gas sensor having a current through it all the time (which is why they are not 9v battery powered). Mine has only gone off twice, once when her indoors was using an aerosol polish (butane propellant) and most odd when I spilt some beer next to it.

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Radiomariner Rising Star

Radiomariner

Posted
Posted (edited)

The OP's link depicts a combined LPG and CO detector/alarm. Probably does what it says. However, it does not mention anything about LPG sensor being remote. LPG being heavier than air sinks to the bottom of the boat, a sensor therefore should be down near or under the bottom boards (Yes, bilges). By comparison a CO detector should be considerably higher, nearer face height. If LPG is detected at that level it could be too late. Good LPG detectors have a control/alarm unit and two or more sensors low down connected by cable. Some have a single sensor inside the control/alarm unit with a vacuum pump sampling air via tubing to various locations low down in the vessel. Two downfalls 1. Considerably more expensive. 2. Because of the remote location of the sensors and their vulnerability to damage frequent testing/maintenance may be required. Such testing usually requires release of a small quantity of a test gas near the sensor.

 

Edited to add:- Found a Suitable, and inexpensive, LPG alarm only device as an example that fits my description. See link below

 

http://www.marinescene.co.uk/product/1851/pilot-dual-gas-alarm/?gclid=CK6g7IWrycICFfQatAod6GQAiQ

 

Without sufficient information I am neither recommending or castigating this particular device

Edited by Radiomariner
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magnetman Veteran II

magnetman

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Posted

Thanks for the replies

 

It would be feasible to use a fixed position LPG sensor in my situation as I am looking for a unit to mount at a low level in the engine bay :) The LED display appeals to me as it can be viewed through a little window in the engine bay covers without needing to be lit up with a torch.

 

I have 3 normal LCD CO detectors in the living quarters but was thinking it might be worth putting one in the engine room as well as that is where I have the Mikuni heater although I'm not sure if they generate CO or not if leaking :unsure: the LPG detection capability would be a 'bonus' on top in the product I linked to.

 

 

Strange that they go off with spilled beer !!

 

 

 

 

 

 

 


Mine states life of 5 years in the manual, It's to do with the gas sensor having a current through it all the time (which is why they are not 9v battery powered). Mine has only gone off twice, once when her indoors was using an aerosol polish (butane propellant) and most odd when I spilt some beer next to it.

 

Thats interesting. I suppose that means that it wouldn't degrade over time without being powered up ?

 

I know nobody can say for sure but I was wondering if just having one sitting round on a shelf for ages would basically mean it was more or less useless after 5 years or whatever...

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Keeping Up Veteran II

Keeping UpDonate to Canal World

Posted
Posted (edited)

I asked the same question of my LPG alarm supplier (Seath Instruments). They responded that the sensors normally have a life that is well in excess of 10 years, and do not degrade in the same way that CO alarm sensors do, but they recommend they should be tested at least annually by holding an unlit cigarette-lighter in front of them.

 

 

ETA I asked only about working life, not shelf life.

Edited by Keeping Up
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Proper Job Veteran

Proper Job

Posted
Posted

An interesting topic

 

The 'new' boat has got a LPG leak detector fitted and I was looking at it at the weekend

 

The installation is a bit strange. The alarm unit (inc sounder) is fitted in a cupboard under the sink and the wires to the detector head go under the floor in to the bilges

 

Given that the floor is fairly well sealed with floor boards and carpet etc, and that all of the gas pipe work is above said floor boards and carpet, I wonder how effective it would be in the event of a leak?

 

How much gas would build up in the cabin space before enough seeped under the floor to set off the alarm?

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wiltshirewonderer Collaborator

wiltshirewonderer

Posted
Posted

I've got one of these. Leaky gas and aerosol cans both tested and set it off.

 

http://www.ebay.co.uk/itm/Mercury-350-134-Natural-Household-Gas-Leak-Detector-Alarms-Mains-Powered-White-/351236843588

 

Requires inverter but I tend to have it on or be on hookup (Upgrade to 12v job is on the todo list)

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trackman Proficient

trackman

Posted
Posted

We have had an LPG detector for over 8 years and it still appears to work. The detector is just above floor level in our case, as recommended in the instruction manual.

It gave us an early sign of alternator problems, if only I'd recognised it! It began to go off fairly regularly as the batteries approached full charge when the engine was running.

It was only after finding that the alternator regulator had begun to run at much too high a voltage that I realised that the alarm was detecting methane from the gases emitted by the batteries.

Methane is of course in the same family of gases as butane, propane etc.

Ethane is another, which may explain the spilt beer alarm incident mentioned earlier. Ethane is very closely related to ethanol (alcohol), so maybe alcohol vapour triggers the alarm the same as ethane would?

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blackrose Veteran II

blackrose

Posted
Posted (edited)

I think there is a PBO gas alarms on test article pinned somewhere on the forum? If you Google Practical boat owner gas alarms on test, you should be able to find it. I think it's also listed under the Jeanneau owners forum.

 

Anyway, I may be wrong, and the technology may have moved on since the article, but my understanding is that the sensors in the cheaper alarms are adversely affected by moisture and do degrade over time. And, since the alarm sensor should be located in the bilges this issue is not insignificant.

Edited by blackrose
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