Lpg

[Clyde_Wanderer]

I have been reading through the BSS LPG installations regs for boats, and cant quite fathom something out.
Bottles should be kept in a locker which is sealed from the hull of the boat, yet in another part it says, " locker lids dont have to be LPG tight, as a air vent will allow air in and the drain will let any escape drain out. So how can the locker be sealed from the hull if the lid is not LPG tight?,
I had made a gass locker last year from 12mm ply, and completly glassed inside and outside, but my challange was to make a good seal between it and the lid, which I havent managed to do yet.
So does this mean I maybe wont have to get it air/gas tight?
Any good advice appreciated.

 

[Searush]

Usual caveats - I'm no expert, but my opinion is;-

You are supposed to stop the gas (heavier than air) from getting into the bilges/ cabin/ hull areas. There needs to be a drain overboard from the locker and the lid should open into the open air so it doesn't need to be sealed. LPG escaping into the cockpit area is not ideal, but there should be enough air circulating to disperse it, preventing a build-up to explosive levels (very low - approx 1:20 or less I think) or asphyxiation (very high levels).

So, provided the locker is accessed from the cockpit you don't need to seal the lid - and I suspect it would not be permitted to have access from inside the boat.

 

[oldsaltoz]

G'day Eamonn ,

LPG is heavier than air, so the box must be gas and air tight from the lid down but the lid itself, because any leakage will go to the bottom of the box and drain outside the hull through the drain pipe that must also be fitted, it is very important that the connection between box and pipe and pipe and overboard drain to hull are air tight.

It's simple on a Cat, just drill a hole on the bottom of one of the forward hatches and make up a frame to hold the bottles.

Hope this helps.

Avagoodweekend......

 

[morgandlm]

I don't think there is any contradiction here if the locker can only drain outside the hull and that any gas escapes from the locker have no direct route into the hull. The gas locker in my boat is under a cockpit seat and has a lift up, unsealed lid. The locker drains into the cockpit, not the hull. The answer to your question will depend on where you have located the new gas locker.
Morgan

 

[Clyde_Wanderer]

Thanks guys, Hi Brian.
I want to fit my gas locker into the lazerette, which is the only place I can put it, but the lazerette has a sealed lid, (to outside the boat, ie water tight) but it its internal space is not sealed to the inside of the boat.
So does my gas locker lid need to be air/gas tight now.
Also where can I buy them?
Cheers.

 

[oldsaltoz]

<<I want to fit my gas locker into the lazerette, but the lazerette has a sealed lid, (to outside the boat, ie water tight) but it its internal space is not sealed to the inside of the boat. So does my gas locker lid need to be air/gas tight now.
Also where can I buy them?>>

No, as long as you have a drain hose/pipe fixed to the bottom that runs to the outside of the hull above the water line (including when heeled).

As headroom can be limited in the Lazerett you could look a using the box you made and use the underside of the deck as a lid, clip the box under the deck and run the hose to the middle of the transom below the box in it's secured position. If you have enough room to mount the box on the transom and still be able to lift a bottle into it from the top, you can dill a hole through the transom and box after glassing it to the transom.

Go for sloping bottom on the gas locker, this will help keep it well drained of gas and moisture.

If you think of the gas as water and the need to drain it overboard rather than into the hull you should be fine.

Hope this helps.

Avagoodweekend......

 

[Robin2]

Also, bear in mind that if the lid is airtight then fresh air will not be able to get in to "flush" any gas out through the vent at the bottom - so you could have a dangerous build up of gas in the gas locker itself.

 

[Maree]

Current regs require a high level as well as a low level drain to promote the air flows through the locker.

 

[Clyde_Wanderer]

Sorry to sound stupid here, but does this mean that if I fit it in the lazerette and ,as Oldsaltoz says have the drain through the transom and an air intake at, or above level of the regulator, that I wont have to have a airtight lid specifically for the locker itself?
Thanks guys.

 

[oldharry]

LPG is only slightly heavier than air, so can be blown around. An airtight lid is a useful precaution so that draughts do not blow escaped gas into the boat. In a major leak situation - such as a fractured pipe, the rate of escape could exceed the drains capacity, also the upper vent would also act as a means of carrying gas clear of the hull. If the lid was not airtight the gas could go anywhere.

 

[MrCramp]

My lpg is in a lazarette which has a very close fitting lid so if water was taken over it , it is unlikely any would enter the locker. Inside is a stainless steel box, like a giant biscuit tin which has a stainless lid which fits on top . The top of the gas cylinder is about 3 inches below the top of the tin. There are two pipes that go into the box. One goes out at the bottom of the box (It is fixed with a skin fitting to the box), through the lazarette and then through the hull, all the time it leads down so gas would vent. The other pipe fixes to near the top of the box and then runs about horizontal through the lazarette and again through the hull.

So I have a low-down drain and a high level air intake.

CLYDE, your post at 09.49 is correct.

 

[oldsaltoz]

Eamonn,

You do not need an air tight lid, a simple a space saving install is a sliding box, this box with bottle and regulator inside, with line appliance coming out and the drain line from the bottom connected to the transom, making sure the line has no loop that will hold water in the low section like an 'S' bend.

The box has a small inverted "L" shape on each side and the underside of the deck has 2 more "L" shaped slides, (the right way up, but turned the other way so you have one set of slides (on the box sides) and another set Fixed to the underside of the cockpit, By setting them both at a slight angle the box will get closer to the underside of the cockpit as it's pushed toward the transom, this will close the gap at the top to prevent gas spillage or wind blowing it out, but still leaving enough gap for fresh air via the slot the feed hose exits the box.

I will send you an e-mail with a rough drawing, you might want to post it for others info.

Avagoodweekend......

 

[Birdseye]

[ QUOTE ]
Thanks guys, Hi Brian.
I want to fit my gas locker into the lazerette, which is the only place I can put it, but the lazerette has a sealed lid, (to outside the boat, ie water tight) but it its internal space is not sealed to the inside of the boat.
So does my gas locker lid need to be air/gas tight now.
Also where can I buy them?
Cheers.

[/ QUOTE ]

Way I understand the rules, you cannot fit your gas locker inside another locker in the boat. Indeed, when I bought my boat (a bog standard 1991 Moody) the surveyor explained that the gas installation (bottles insice a cockpit locker with a drain for the gas) was no longer legal. So I checked up on what was required and have a longish doc I can send you be e mail if you pm me your address. What it seems to boil down to is an entirely seperate locker that must have a gas tight lid, a drain exiting above the waterline and the lid of the locker must have a certain relationship to the height of the bridgedeck. havent re-read the document so dont rely on the above for absolute accuracy.

TBH I havent yet done anything about the problem and having seen the results of two gas explosions on board, that leaves me nervous. But the requirements arent really feasible in my boat. /forums/images/graemlins/confused.gif

 

[Searush]

Quote
I want to fit my gas locker into the lazerette, which is the only place I can put it, but the lazerette has a sealed lid, (to outside the boat, ie water tight) but it its internal space is not sealed to the inside of the boat. unquote

It MUST be sealed from the interior of your boat and drained outboard. It gas can get into your boat, it will tend to collect in the bilge & could explode or if there is a lot of it, suffocate you!

 

[Clyde_Wanderer]

Thanks everyone again for the latest replies.
Because of the shape of my hull and the very low free board at the transom/cockpit area, even using the smaller camping gaz bottles and a locker to suit is becoming a real challange to design, taking into consideration locker height allowing for a continues fall for the drain pipe, accessability, and sealing from boat interior.
There is infact not one part of the boats interior which is sealed from any other part, except the cockpit well which is watertight from the rest if the boat, once the cockpit sole is clamped down.
Cheers, Eamonn,

 

[VicS]

Perhaps the you should be considering a locker with a lid that does seal. That will mean though that the locker will need a vent pipe.

The problems of a shallow hull and getting a continuous fall in the drain pipe can be over come by making the drain connection to the locker above the very bottom of it and filling the space around the bottle up to its level. The BSS does describe that possibility.

BTW if using a bulkhead fitting to take the gas connection out of the locker drill the land out of the centre of the fitting so that a continuous length of pipe can be passsed through it so eliminating two joints and two possible leakage points. If you are using a bottle mounted regulator use a bulkhead hose connection at the exit point. Then you have the hose from the regulator to the fitting inside the locker and the copper pipe leading away from it outside the locker.

 

[pappaecho]

Follow the US system. Put the gas bottle in metal cage and put it on the pushpit, so it is in the free air, and does not have any possibility of heavier than air gas getting into the bilges.