Gas in a bag?

[pugwash]

I have read the earlier post about gas bottles but I have a slight different question.

Finding room in my cockpit locker for one bottle in an airtight box with vent to overboard is not hard, but storing the second or spare bottle is a real headache.

What do you think about keeping the spare (either full or empty) in an air-tight bag and carefully secured in the locker? Or even in something like one of those big plastic storage bottles? There are no joints to leak except the cylinder's main valve, and if that were leaking the bottle would now be empty.

I want to do this gas stuff properly with everything safe. Would this be safe enough?

 

[Malcb]

No, definitely not. The sealed container would have to be able to withstand the pressure of the gas if it escaped from the gas bottle. Venting to atmosphere, in a gas locker, enables the pressurised gas to escape to atmosphere, while the pressure in the gas locker remains at atmospheric pressure.

 

[LORDNELSON]

Many people carry their spare gas bottle outside the gas tight locker and I cannot see why it should be a problem; after all the spare bottle has a tightly screwed cap in it to stop the gas coming out! I think the reason for putting your service gas bottle in an gas tight locker is because it is turned on and it may leak at the joint/s, regulator etc.,

 

[Thistle]

Hm! How long would a bag with a lump of metal rattling about inside it remain air-tight? Or imagine a gas bottle leaking in an air-tight bag. Wouldn't the bag inflate until either the bottle was empty or - more likely - the bag burst like a balloon. Similarly with a plastic bottle unless it were as strong as the cylinder itself.

The bottle must be stored where there is no possibility of a leak into the bilges or any other space where the gas can't drain from the lowest point.

Any space round the deck or transom for a suitable container for the cylinder? Or in the anchor locker?

 

[Sans Bateau]

Keep my spare bottle in the anchor well, it has plenty of room and drains over board. No good of course if you have one that drains into the bilges!

 

[Kilter]

Did you see the Dad's Army episode or film where they convert jonesy's van to gas with a big bag?

 

[LORDNELSON]

Interested in your point about "where the gas can't drain from the lowest point". About a month ago I was shot down in flames by a contributor because I recommended leaving one's log through-hull hole open during the winter so that any gas mixture could drain out (from above the level of the through-hull, of course); the contributor said the gas would mix with air and thus not drain. Whilst I accept that gas mixes with air it does result in a heavier gas/air mix which, I believe will tend to drain to the lowest point.

On the point about where to store the spare gas cylinder, the anchor locker is a good choice if there if plenty of room and the chain running out will not catch the gas bottle and maybe jerk at the stopper? Are we all becoming a little paranoid about this matter? I cannot see that a properly stoppered spare gas bottle is a risk. What about the small cruisers who rely on a gas ring screwed into a gas bottle?

 

[Thistle]

As with any gases, there will be mixing so, as VicS told you in the earlier thread, expecting it all to flow out of a hole at the lowest point won't get rid of the whole problem. However the mixing will occur slowly in still air conditions (as in a closed boat) and until mixing occurs the denser gas will tend to flow to the bottom of the space so a hole there will help to reduce the amount of gas in the boat. I reckon that anything which reduces the risk of an explosion afloat is worth considering.

 

[snowleopard]

Several contributors think there is no risk of leakage with a full bottle not connected to the pipework.

I once saw a truck carrying several hundred bottles driving through central London. I smelled gas and noticed that one of the bottles was covered in frost so was obviously in the process of emptying itself. He drove off before I could flag him down and I didn't hear of any major explosions at the time so presume it just vented without igniting. So yes, the valve can be opened by vibration.

 

[Superstrath]

Yes, I found a bottle floating in the marina last year. Once I'd fished it out, I realised it was leaking from the top. I wasn't about to chuck it back in, but I couldn't stop the flow. In the end I put it in a breezy place and guarded it until it was empty!

 

[bills4us]

Gas, propane or calor must be vented overside NOT stored in board, unless in a vented locker.
Air consists of 78% niitrogen 21% oxygen and 1% noble gasses it supports life in that state and is not dangerous. Add any of Calor/propane through a leak, it being heavier than air will settle at the lowest point, the bilges. The air then becomes enriched and Very Dangerous a spark is all that is needed any where in that area and you are in deep s**t.
Bilge blowers are not always the answer,good ventilation is ,common sense is better.
Do Not Store any gas or petrol in unvented lockers

 

[Malcb]

New gas cylinders can leak. That is why suppliers of new cylinders have to store them in a ventilated cage outside. Therefore, even on a boat, gas cylinders should be stored in a draining, to the outside atmosphere, locker. A draining anchor locker would also work.

The same applies to petrol.

 

[sailorman]

as is the same with petrol

 

[webcraft]

We keep our spare bottle in a plastic bucket with a sealed gastight lid. In the event of a leak it would of course blow the top off the bucket, so it is a bit of a compromise . . . at least we would know it had leaked if we spotted it before it blew us up.

One possible solution we are looking at would be to put a vent in the bottom of the sealed bucket and store it on the transom. Ideally the vent would be in the form of a length of hose that went overboard.

I wouldn't get too paranoid though . . . gas explosions are truly horrible, but I imagine they account for a very small percentage of boating accidents. Does anyone have the statistics?

A reliable gas alarm in the bilges is a sound idea though . . .

- Nick

 

[tome]

[ QUOTE ]
A reliable gas alarm in the bilges is a sound idea

[/ QUOTE ]

Find me such a beast. Gas detectors just hate damp

 

[William_H]

If you really don't have room in the vented locker for a spare gas bottle and must have a spare then your best bet would be to put it in a large plastic bottle. This should have a vent hole. The bottle can be stored near the transom in open air with hopefully no access to the bilges but only overboard via cockpit drains. The plastic bottle of course protects the gas bottle from the elements.
olewill

 

[LORDNELSON]

Well mine seems to check out OK each time it is tested (once a year when the whole system is pressure tested), but our bilges are generally dry (and I hope they continue to be!).

 

[BSSOffice]

[ QUOTE ]
We keep our spare bottle in a plastic bucket with a sealed gastight lid. In the event of a leak it would of course blow the top off the bucket, so it is a bit of a compromise . . . at least we would know it had leaked if we spotted it before it blew us up.

[/ QUOTE ]

LPG one known as a searching gas, that means it could find its way out of some forms of container otherwise considered sealed. An uncontrolled escape may be prevented by a drain that controls the destination of the gas...
[ QUOTE ]
One possible solution we are looking at would be to put a vent in the bottom of the sealed bucket and store it on the transom. Ideally the vent would be in the form of a length of hose that went overboard.

[/ QUOTE ]

[ QUOTE ]
I wouldn't get too paranoid though . . . gas explosions are truly horrible, but I imagine they account for a very small percentage of boating accidents. Does anyone have the statistics?
- Nick

[/ QUOTE ]

I believe, without trawling through our spread sheet (time pressures) we have perhaps, a couple of confirmed gas explosions on boats recorded last year - out of around 50 fires and explosions. However in just under a thrid of the total the cause is 'unknown'. We also believe that our data does not form a complete record of all fires and explosions on boats in the UK.

When I have some time, I will go through our records and test a hypothesis that there is always someone onboard when there is a gas explosion on a boat, ie providing the ignition trigger and sometimes the gas escape, but that is for another time.

 

[BSSOffice]

[ QUOTE ]
[ QUOTE ]
A reliable gas alarm in the bilges is a sound idea

[/ QUOTE ]

Find me such a beast. Gas detectors just hate damp

[/ QUOTE ]

At the London Boat Show, one of the visitors to our stand was a manufacturer of a detector with a new sensor that he claimed could withstand the odd immersion in the bilges. I predict that if you keep reading the magazines the product info will be published in due course.

I'm afraid I have no details.