Gas detection

[Graham_Wright]

A gas sensor head should be placed in the bilge where spilled gas will collect. Unfortunately, this is where water also collects and sensors do not like water.

One solution may be to sense the output of a bilge blower (in suck mode). Situated away from the bilge it should suck only gases and not water.

However, if it is not spark free, it could turn into a flame thrower.

Can anybody advise if, for instance, the Rule bilge blowers are spark free?

 

[VicS]

If you down load the instruction manual ( called datasheet) from the website you will see them installed as vapour extractors rather than as air blowers!

Don't forget to also fit gas sensor heads below the most likely sources of gas escapes ... namely the gas appliances themselves. A properly fitted installation should not be at all likely to allow gas to escape into the bilges.
.

 

[Mrnotming]

Gas sensor

put your sensor head over the cabin sole and drill a hole under it to allow any lurking gas to set it off! If you have loads of bilgewater set about finding out where it is coming from and eliminate this problem and then arrange to have nice clean dry bilges On one boat I owned I found 13 separate leaky areas, some from the time of factory building (wood screw in toe rail instead of machine screw and bolt).If your boat is getting wet during racing, forget the sensor and leave the gas bottle in the garden shed!
There is a device I believe which fits on the gas bottle and warns of any leakage in the system whilst gas is turned on.

Good sailing and boating to all.

 

[Graham_Wright]

If you down load the instruction manual ( called datasheet) from the website you will see them installed as vapour extractors rather than as air blowers!

Don't forget to also fit gas sensor heads below the most likely sources of gas escapes ... namely the gas appliances themselves. A properly fitted installation should not be at all likely to allow gas to escape into the bilges.
.

Thanks Vic, first off the mark as usual!

I struggled to find their website but forgot they all belong to ITT. They quote "ignition protected to USCG 183.410".

The word "below" when applied to gimballed cookers is a variable quantity!

 

[VicS]

Out of interest what type/make of gas detector are you planning to use.

I am committed to fitting one ... I should have fitted it last winter... because my gas cooker ( hob and grill, no oven) does not have flame failure devices. I would have fitted a "Pilot" one but was put off by peoples' experience of them sounding for so long when first switched on .... at least one forumite even removed his! (then the cheeky s0d tried to sell it to me)

Thinking about the Nasa one.

 

[Ex-SolentBoy]

Out of interest what type/make of gas detector are you planning to use.

I am committed to fitting one ... I should have fitted it last winter... because my gas cooker ( hob and grill, no oven) does not have flame failure devices. I would have fitted a "Pilot" one but was put off by peoples' experience of them sounding for so long when first switched on .... at least one forumite even removed his! (then the cheeky s0d tried to sell it to me)

Thinking about the Nasa one.

Vic,

I have recently switched from Pilot to Dualwatch and I much prefer the new one. The control panel is not unattractive, and the sensor lead terminates in a plug which you fit into the sensor. This means that you can easily change sensors if you have to. The sensor also has plug sockets both ends so you can daisy chain them for multiple locations.

 

[emandvee44]

Gas Detectors

There are marine gas detectors with waterproof sensors - I am planning to change to this type because my Pilot gas alarm is always going off (without a gas leak) and also the sensors can get damp/wet under the floorboards. A google search will find the waterproof type, or try nereusalarms (MCA compliant)

Cheers,

Michael.

 

[Pasarell]

Gas Alarm

I fitted a Nereus alarm earlier this year. They are expensive but as said above the sensor head can get wet without damage. They also make no noise on start up unless they find a fault - or gas.

 

[lw395]

Out of interest what type/make of gas detector are you planning to use.

I am committed to fitting one ... I should have fitted it last winter... because my gas cooker ( hob and grill, no oven) does not have flame failure devices. I would have fitted a "Pilot" one but was put off by peoples' experience of them sounding for so long when first switched on .... at least one forumite even removed his! (then the cheeky s0d tried to sell it to me)

Thinking about the Nasa one.

Would it not be better to address the problem at source, by fitting a cooker with flame failure devices?

A gas detector should be viewed as an additional warning device. If you have an explosive gas mixture in the bilge/cabin, it may explode before you act on the alarm.
Your current cooker must be ancient and a new, safer one would add value to the boat?
It may be possible to retrofit the valves?

My view is that the detector would best be placed in a fairly open position, near the cooker and at a lower level, but need not be at floor level.
Although the gas is denser than air, it will diffuse in all directions, with a downward tendency. It does not pour downward like a liquid, it mixes with the air and goes in all directions, just a bit more goes down than up. And a lot of that is because the escaping gas is cooled by expansion.
The sensor should therefore be in the main flow of air/gas from the cooker, rather than tucked away in a bilge.
IMHO.
If you have a gas sensor, you need to test it regularly other wise you may trust it falsely.

 

[prv]

Would it not be better to address the problem at source, by fitting a cooker with flame failure devices?

We went round this loop earlier in the year - Vic's cooker is an obsolete one of an obscure size, and no modern version will fit in its place.

Pete