Gas in bilge

[Graham_Wright]

The ones that overheat if run dry?
And if there is a bit of water trapped in the outlet hose, it will stop much gas being pumped.

Mine doesn't and there isn't any trapped water (there can't be can there?)

 

[jwilson]

This thread reminds me of an incident to a friend some years ago. We were at Dartmouth and my friend's wife accidentally turned on a burner on the gas cooker with her hip (before the advent of safety valves) as she was passing. It was several minutes before my friend realised what had happened and turned off the gas. It must have seemed strange to the neighbours as he was seen apparently bailing "nothing" out of the boat with a bucket. He was of course bailing butane out of the bilge. Needless to say I stayed well away until the task was complete (being the coward that I am).

I've done that, bucketed 'nothing' from the bilges, after a gas leak on a chartered boat in Salcombe in the 1980s. My own boats all had paraffin cooking at that time. OK most of the gas probably spilled out of the bucket en-route, but at least it stirred it up into airflow between fore and main hatches.

 

[pmagowan]

I've done that, bucketed 'nothing' from the bilges, after a gas leak on a chartered boat in Salcombe in the 1980s. My own boats all had paraffin cooking at that time. OK most of the gas probably spilled out of the bucket en-route, but at least it stirred it up into airflow between fore and main hatches.

But is that not the major risk, stirring it up to a level where it may come in contact with an ignition source. I would have thought that if there is such an amount of gas that bucketing might be an option (if it ever is) then the last thing you should be doing is standing in the bilges with it. You should get out. Highly concentrated gas in the bilge is unlikely to do any harm unless you light a match, but even a few percent in the air near electronics and switches could go boom.

 

[Lon nan Gruagach]

A good old Davey miners lamp is what you want, the flame stays on the inside and burns any gas that enters.

 

[pmagowan]

A good old Davey miners lamp is what you want, the flame stays on the inside and burns any gas that enters.

All my lamps on board are of that nature because they are small and look cool. They also seem less likely to set fire to stuff. Not sure I would like to test it out though!

 

[KevB]

A vacuum cleaner outside the boat with the nozzle in the bilge and vacuum it out.

 

[Lon nan Gruagach]

A vacuum cleaner outside the boat with the nozzle in the bilge and vacuum it out.

Not too sure about that... I saw someone service a vac with WD40... the gout of flame that came out was quite impressive.

 

[lw395]

A vacuum cleaner outside the boat with the nozzle in the bilge and vacuum it out.

Is this another A22/Sound Barrier suggestion?
My last vacuum cleaner caught fire without any added gas!

 

[pmagowan]

If an elephant passes by he might assist

 

[lpdsn]

If an elephant passes by he might assist

They generate a lot of methane though.

 

[lpdsn]

I accidentally release a small quantity of calor into my bilges, and the gas alarm went off. I was quite pleased that such a small amount triggered it.
However I do not have a bilge blower, will the gas degrade and disperse over time and if so how long. If it doesn't how do you get rid of it without a blower

Open all the hatches and companionway and put an electric bar fire on board with a timer switch. Stand well back with video camera. There is almost certainly not enough gas to be a problem, but if it all goes wrong you'll have an interesting video to post on YouTube. Make sure you make an arrangement for a cut of advertising revenue before posting.

The hydrogen from charging my batteries sets off my gas alarm, so the alarms are very sensitive. And there's not a prob with the batteries as I check the level regularly.

 

[pmagowan]

They generate a lot of methane though.

Yes, you need to use the correct end!

 

[LadyInBed]

The gas might have diffused to 'well above the bilge'.
Gases do that.

LPG sinks
If it has defused that high, then you might also have trouble breathing
We still don't know if the alarm is still sounding.

 

[Daydream believer]

I wonder if this works. It would be interesting to do some kind of experiment. Pumping water and pumping gas are two very different things. I suppose it depends on the bilge pump.

Best thing to do is discharge some gas into the bilge. Try pumping it out with bilge pump. (Do not do anything silly with the electric pump in case there is a spark)
When you are done lob a match into the bilge & see if it glows
Please let us all know how it goes

 

[GrahamHR]

Why on earth would someone have a flammable gas on board with a chance it could get into anywhere on the boat, let alone the bilge, not have a bilge blower ? They are cheap and reliable ; all the USCG approved ones are spark protected.

 

[lw395]

LPG sinks
If it has defused that high, then you might also have trouble breathing
.....

Wrong on both counts.
Gases mix, but not instantly.
Otherwise, you'd find all the oxygen on the floor, because it's a bit heavier than the nitrogen in the air.
A few % of another gas won't affect your breathing unless it's either CO2 which your breathing reflex reacts to, or CO or some other gas that has an effect on the body.

Escaping gas will initially sink, because it is cold from expanding and boiling off the liquid butane or whatever.
Try carrying some gas around in an open top bucket, it won't be enough to light after a few minutes.

 

[rogerthebodger]

Propane is only explosive when the concentration is between about 2 % and 10 %. and so venting with open windows hatches etc and vacate for an hour or two is the best way.

 

[VicS]

Propane is only explosive when the concentration is between about 2 % and 10 %. and so venting with open windows hatches etc and vacate for an hour or two is the best way.

and butane between 1.5% and 8.5%

 

[rogerthebodger]

and butane between 1.5% and 8.5%

Thks Vic

Have you any idea what kind of percentage concentration the average Mk nose might detect. I seem to smell gas befor my hand held Omnitron gas detector does ?

 

[VicS]

Thks Vic

Have you any idea what kind of percentage concentration the average Mk nose might detect. I seem to smell gas befor my hand held Omnitron gas detector does ?

Lpg gases have very little smell so a stenching agent , ethyl mercaptan, is added.

I belive so that the gas can be detected at 1/5 of the LEL ........ I think thats the same as the alarm setting for the Omnitron but people's sense of small varies enormously. Mine is like yours, quite sensitive.