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Gas bottle storage


IanR

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Hi folks. On our soon to be fitted out boat, we intend to store the gas bottles under the wooden 'back end planks' in front of the engine room. There is a steel floor under them now and I'm wondering if we can make up a steel (lidless) box with a flange around the top that we can drop it into a hole in the steel, sealed and bolted or perhaps it needs to be welded? I understand it would need a vent to outside at the bottom of the box, what does this vent need to be made from? Could it simply be a suitable sized hose onto two fittings, one on the box and the other on the hull, thus giving the ventilation? Or does it need to be a steel tube with no removable couplings etc? Perhaps there are fittings available that allow the tube to protrude through them so there are then no joins 'inside' the boat? The space under the planks, where the vent will be will be taken up by the fresh water tank and would be inside the 'converted' boat. I could post a pic of the proposed position if my description is non too clear!

We are just gathering info for our fitout which we'll be starting when we get round to it!

Cheers, Ian.

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33 minutes ago, IanR said:

Could it simply be a suitable sized hose onto two fittings, one on the box and the other on the hull, thus giving the ventilation?

Yes. Note that it’s not ‘ventilation’. It’s a drain and must run downhill from the locker to the outside. It can be a hose and must be of the correct size and securely clamped. It’s all there in the guide. 

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Thanks for the link Wotever. It would seem possible though the issue that crops up immediately would be the 1m proximity to an aperture into the boat. The triangular bulkhead from the planks into the hold would be within this 1m and will have a window and escape hatch in the middle of it. This seems from my reading of the rules to only apply for 'open air' storage. Our set up, although basically open air, has a drain well below this aperture so it may comply as is, though putting a lid on the box and turning it into a locker would seem to make it compliant anyhoo, unless I've read things on the squiff?

painted side.jpg

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I dont understand what your plan is but for an open top locker, cant see things but for in the real.

 

But a locker as i see it needs a drain out from it below the top open edge. So i would fill around the cylinder/s with a light weight concrete, mix if cement and vermiculite to the level of a drain hole above watr level to feed the leak of the LPG to out of the hull side by a 15mm copper pipe to a bulkhead fitting. , i assume you are using 13kg calor size.  

 

 

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I think that the thinking goes...

1. Gas is heavier than air so they’re not too bothered about the top of the container as long as it’s above any high pressure components. 

2. The container/locker must be gas tight. 

3. If any gas does leak it will flow to the bottom of the locker, so must be vented from the bottom to the outside with no chance of it going anywhere else. 

All the text appears to just cover all the eventualities of covering those three points. 

Unless I’ve missed something?

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I don't know him apart from he was a nice enough bloke when he did our inspection!! He did say that it'd be fine to run through ideas with him, but for the moment we are just running through ideas. Once we get more I'll pester him with the lot at once!! I have a copy of the BSS booklet rule book too and will certainly be following it and the inspectors wise words thoroughly!

Many thanks again, Ian.

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3 minutes ago, W+T said:

i would fill around the cylinder/s with a lightweight concrete, mix of cement and vermiculite to the level of a drain hole above water level...

I’m not sure that would be acceptable. If the cylinder valve leaked you’d have gas surrounding the bottle in the thin gap, with no way for it to escape. 

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3 minutes ago, WotEver said:

I think that the thinking goes...

1. Gas is heavier than air so they’re not too bothered about the top of the container as long as it’s above any high pressure components. 

2. The container/locker must be gas tight. 

3. If any gas does leak it will flow to the bottom of the locker, so must be vented from the bottom to the outside with no chance of it going anywhere else. 

All the text appears to just cover all the eventualities of covering those three points. 

Unless I’ve missed something?

nope all is good to measwell. reason i said the fill the locker around the cylinders with a lightweight cement to get the floor level up.   

Just now, WotEver said:

I’m not sure that would be acceptable. If the cylinder valve leaked you’d have gas surrounding the bottle in the thin gap, with no way for it to escape. 

from my inspector many years ago and the BSS it says it is ok.

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Just now, W+T said:

nope all is good to measwell. reason i said the fill the locker around the cylinders with a lightweight cement to get the floor level up.   

Yeah, I realised that but it’s not really the floor, is it? It’s more like a cement jacket. 

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1 minute ago, WotEver said:

Yeah, I realised that but it’s not really the floor, is it? It’s more like a cement jacket. 

i remember seeing a diagram on the BSS file, cant find it know...bear with ;)

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1 minute ago, IanR said:

We are planning on making the locker big enough for two bottles, smaller than the 13kg jobsters. This way the locker bottom would be well above the waterline and therefore drainable.

So that the 6kg/7kg or less then the 3.9kg or 4.5kg then its simple, all you need is it made from the correct material as in the BSS and a drain as stated from the floor level. the better down slope then the better it is.

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8 minutes ago, W+T said:

i remember seeing a diagram on the BSS file, cant find it know...bear with ;)

Yes, the older guides had pretty pictures. I think the part of the current guide that relates is this:

Any area in the cylinder locker below the drain that could retain leaked LPG must be filled with LPG‐resistant material.

However, it appears that it’s not relevant in this case anyhow. 

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10 hours ago, WotEver said:

Yes, the older guides had pretty pictures. I think the part of the current guide that relates is this:

 

 

However, it appears that it’s not relevant in this case anyhow. 

All sorted then, that was easy :)

 

 

 

 

 

Air tight box upto the lid, copper pipe to keep it straight for the drain to get from the bottom on the locker to the hull fitting. 

Make the box deep enough so then the exit pipe from the bubble tester or what ever is being used is above the cylinder. 

Cabinet hose will be fine as long as it has a good straight fall, fatsen it to a batton or something.

 

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3 hours ago, W+T said:

All sorted then, that was easy :)

 

That was easily sorted wasn't it!!?? Don't worry, there'll be far more for you all to ponder over soon enough!! Just need to check on the sizes of the bottle, regulators etc etc and then knock up a steel box to suit. It would seem that the box doesn't need a steel, sealed lid, just one that will protect the internals from damage from falling things, so the timber back end planks will do that admirably. The cabinet will be fairly close to the hull with a welded tube on the hull for the hose connection, ground off flush on the outside. There doesn't seem to be a definite height above waterline for this hull fitting, though the rest of the hull fittings in the bss booklet seem to indicate between 10" and 12" as ideal?

Ian. 

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23 minutes ago, IanR said:

There doesn't seem to be a definite height above waterline for this hull fitting, though the rest of the hull fittings in the bss booklet seem to indicate between 10" and 12" as ideal?

Yeah, they get all upset if openings aren’t (I think) 250mm above water level. But it’s only an advisory for private boats. If you are able to achieve 300mm then there’ll be no questions. 

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16 minutes ago, WotEver said:

Yeah, they get all upset if openings aren’t (I think) 250mm above water level. But it’s only an advisory for private boats. If you are able to achieve 300mm then there’ll be no questions. 

They shouldn't on a private boat. Lots of gas lockers are at water level  with the cut sloshing in and out

 

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15 hours ago, IanR said:

We are planning on making the locker big enough for two bottles, smaller than the 13kg jobsters. This way the locker bottom would be well above the waterline and therefore drainable.

 Here are some sizes, Not a lot of difference between the 6kg and 13kg but the price of the smaller one is only a little less than the 13. Some other gas companies sell an 11kg which is lower in height but not easy to obtain in all areas. 

 

Cylinder Type/Size Height Diameter
Butane 4.5kg 340 mm 240 mm
Butane 6kg BBQ Gas 314 mm 306 mm
Butane 7kg 495 mm 256 mm
Butane 15kg 580 mm 318 mm
Propane 3.9kg 340 mm 240 mm
Propane 5kg Patio Gas 314 mm 306 mm
Propane 6kg 495 mm. 256 mm
     
Propane 13kg 580 mm 315 mm
     
   

 

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42 minutes ago, ditchcrawler said:

They shouldn't on a private boat. Lots of gas lockers are at water level  with the cut sloshing in and out

 

 

29 minutes ago, WotEver said:

Yeah, you’re right :)

Under these circs, painting the base and a little way up the sides with Comastic or similar is an extremely good idea, as is doing the same with the stern bilge under the stern gland.

(I know that's all been said before, but this thread will be of interest to all those designing their own boats.)

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15 hours ago, W+T said:

But a locker as i see it needs a drain out from it below the top open edge. So i would fill around the cylinder/s with a light weight concrete, mix if cement and vermiculite to the level of a drain hole above watr level to feed the leak of the LPG to out of the hull side by a 15mm copper pipe to a bulkhead fitting. , i assume you are using 13kg calor size. 

It's highly unlikely that would be compliant.

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1 hour ago, IanR said:

It would seem that the box doesn't need a steel, sealed lid, just one that will protect the internals from damage from falling things, so the timber back end planks will do that admirably.

I shall probably get shouted down again by certain members for stating risks perceived to be non -existent or near non-existent, but here goes anyway......

Firstly, I think what you are proposing will be OK BSS wise - no issue there I think.

But if it were mine I might be a bit worried that if there was some failure that resulted in more than a small leak, that maybe not all fast escaping gas would pour out through the drain(s), and that some might actually flow over the lid of the box.

The same of course is  true if the gas is in a bow locker, (as ours is), but it has always seemed to me that if the worst occurred, most gas that over-topped a bow locker would roll across the deck, and over the sides of the boat.

If your box is inside the boat, then in the same siltation the gas would over-top the box, and fill the bilges.

I'm not saying "don't do this", just be aware that it may not be as fail-safe arrangement as what exists on many boats.  Think about split hoses, or bubble testers that could (some say!) get damaged. (Hoses worry me more than a bubble tester, which I think are actually adequately robust, even if bashed when getting cylinders in and out).

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1 hour ago, alan_fincher said:

I shall probably get shouted down again by certain members for stating risks perceived to be non -existent or near non-existent, but here goes anyway......

Firstly, I think what you are proposing will be OK BSS wise - no issue there I think.

But if it were mine I might be a bit worried that if there was some failure that resulted in more than a small leak, that maybe not all fast escaping gas would pour out through the drain(s), and that some might actually flow over the lid of the box.

The same of course is  true if the gas is in a bow locker, (as ours is), but it has always seemed to me that if the worst occurred, most gas that over-topped a bow locker would roll across the deck, and over the sides of the boat.

If your box is inside the boat, then in the same siltation the gas would over-top the box, and fill the bilges.

I'm not saying "don't do this", just be aware that it may not be as fail-safe arrangement as what exists on many boats.  Think about split hoses, or bubble testers that could (some say!) get damaged. (Hoses worry me more than a bubble tester, which I think are actually adequately robust, even if bashed when getting cylinders in and out).

My boat has the gas locker in the semi-trad stern (a far more sensible place than in the bow locker) and this is far from unusual. I suppose you could say that in the situation described above it would be possible for some gas to get into the bilge, especially if the rear doors were closed.  The difference probably is that the locker drain is fairly large. If I was building a gas locker inside the boat as the OP is suggesting, I would want a bit more than a piece of rubber tube acting as the locker drain.

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