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Quote: Originally posted by Acting_strange on 20/5/2007

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Its actually caused by the evaporation of the gas....Try wrapping the cyl in some layers of bubble wrap

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You might not be able to do that if the canister fits into a compartment on the stove. All gas canisters and cylinders get cold and the longer they are used the colder they get...which can be a help in determining how much gas you have left in the larger bottles by the condensation on the outside.

I used to use a stove with canisters and never found a problem with them getting too cold and losing pressure though.

The vaporisation process absorbs heat from the liquid, so by wrapping bubble wrap around the canister you would prevent this heat from being replaced and would actually make the problem worse.

Just to clarify - when a gas evaporates, it needs energy/heat.  The 'gas' in the canister is a liquid because it is under high pressure (which is why you can hear it sloshing around).  When you open the valve, the pressure drops, allowing some of liquid to change to a gas.  The energy/heat needed to evaporate the gas is drawn from the surroundings - which is why the cannister feels so cold. The same principle is used in the back of a fridge/freezer to draw heat from inside it.  That's also how evaporating sweat cools you down (and is even colder in the wind because it evaporates faster).  The reason why the flame goes down is because a drop in temperature also causes a drop in pressure.  Sorry to be a bore, but I'm a science teacher - I can't help myself!

I sometimes have to resort to warming cylinders with my hands, which definitely works, though it's obviously not much fun, but to be honest that's only really when I'm getting the last few drops out of cylinder, when the pressure drops anyway.

On a vaguely related note, a friend who did lots of motorbike touring/camping had an Eastern European stove that ran on petrol.  The cannister containing the petrol actually sat in the flame  which warmed the petrol up to make it evaporate!!  Not quite sure that would get though UK safety regs!!

Propane would be ok at much lower temperatures; I have a little stove that uses a screw-on cartridge, they are usually a butane-propane mix.

I guess if you can't get propane for your stove then all you can do is try to keep the cartridge warm, or try not using it at full power if it's cold.

But here is a good lesson about cooling through evaporation www.asciimation.co.nz/beer/