LPG bottles - laying on side
Submitted: Wednesday, Oct 08, 2003 at 22:01
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rodeoowner
I haven't visited for quite a while and just read an old post on laying LPG bottles on their side.
This is a major no-no. It has nothing at all to do with the rubber seals etc. The PRV (pressure relief valve) is at the top of the cylinder. In the event that there is a major pressure build up (usually from over filling or extreme heat) the PRV will release and gas vapour will come out until the pressure has dropped back down to an acceptable level. If the bottle is laying on it's side the PRV is in the liquid section, not the vapour. If there is a major pressure build up the vapour cannot escape through the PRV. The PRV will not activate and the only way out for the vapour is through the side of the cylinder, that is, it will explode. This is known as a BLEVE.
Legally the amount of LPG that can be stored in the passenger compartment of a vehicle is 25.4 litres. There are approximately 2 litres to every kg of LPG. This is set out by the Australian Dangerous Goods Code. There used to be a ruling in AS1596- Storage and Handling of LPG which stated (from memory) 2kg. This was taken out in 1996 (from memory). To me, personally 25.4 litres seems crazy. I wouldn't carry any inside a vehicle if I could help it. You can buy plastic plugs to screw into the cylinder valves from camping shops.
Hope this helps.
Reply By: Truckster (Vic) - Thursday, Oct 09, 2003 at 10:09
Thursday, Oct 09, 2003 at 10:09
Actually a BLEVE is a Boiling Liquid Expanding Vapour Explosion usually caused by heat. Excess pressure and excess heat are 2 different things with this. There are some good vids available on BLEVEs, done by NSW Fire Service, we used to use these for training courses we ran.
Basically they both rely on the Relief Valve to vent, but are actually different. As it says one is caused by heat expansion, one is caused overfilling pressure.
Also knows as Bloody Loud Explosion Very Exciting, specially if you have been there when one happens. :)
Also in reality carrying a 24 ltr gas cyl inside or out (Roof Rack) of your car is going to almost certainly end in the same result...
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Follow Up By: rodeoowner - Sunday, Oct 12, 2003 at 16:26
Sunday, Oct 12, 2003 at 16:26
Not trying to be a smart alec Truckster, but when LPG is in the cylinder it is boiling. When you raise the pressure, the boiling point lowers. Excess pressure and excess heat may be different things, but they are closely related. When LPG is heated, the pressure rises, in turn causing a BLEVE.
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Follow Up By: Truckster (Vic) - Monday, Oct 13, 2003 at 22:30
Monday, Oct 13, 2003 at 22:30
You can have excess pressure without heat though... Which isnt a BLEVE.
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Reply By: Member - Wherethehellawi - Thursday, Oct 09, 2003 at 18:30
Thursday, Oct 09, 2003 at 18:30
If I am not mistaken the pressure relief valve should relieve excess pressure wether it be vapour or liquid. the prv is to stop an explosion and it does matter if the cylinder is upside down on its side or standing up. It has to be fail safe to prevent the explosion due to excessive presures.
If they had to be standing up it would be marked all over the cylinder and also clearly marked. It scrap that a cylinder must stand up to allow the safety valve to operate.
They use similar prv valves in refrigerant cylinders and I have seen one go off when on its side due to over filling.
Boc gases do not use the bleed method of refilling cylinders but rather they weigh. If a cylinder is cold it can accept more liquid gas without being immediate dangerous. But when the cylider warms up its a different story. If over filled the contents are fully saturated and can be considered to be all liquid. The prv will release at the presure it is designed to go off at. It does not matter if its vapour or gas.
I may stand to be corrected but I think its baloney that the cylinder must be upright to allow the SAFETY valve to go at its designed setpoint!.Wow! am I cute
If yer ain't fishing, Yer ain't livin
Richard
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Follow Up By: rodeoowner - Sunday, Oct 12, 2003 at 16:31
Sunday, Oct 12, 2003 at 16:31
Hey. Gas cylinders are filled by two different ways. Bottles 9kg and lower are filled using the bleeder valve. When the cylinder reaches 85% capacity the liquid will come out of the bleeder valve. Then you know it is full. Cylinders over 9kg are filled by weight.
If the PRV opens and liquid comes out, you will get 270 times the amount of gas out, rather than if it was vapour.
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Follow Up By: Member - Wherethehellawi - Monday, Oct 13, 2003 at 08:11
Monday, Oct 13, 2003 at 08:11
non the less,
the prv will open at the set pressure and relieve the the presure on the cylinder.....Whether its upside down or not!!
(BOC only use the weigh method as their cylinders Do Not have a bleed valve.)
And the contents of a static liquified gas cylinder is not boiling. It only boils when the presure is reduced in some way. Wow! am I cute
If yer ain't fishing, Yer ain't livin
Richard
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