Filling a gas bottle from another

[yourguitarhero]

I have a big gas bottle (500g) with lots of gas in it, a small gas bottle (230g) with not very much gas in it and a widget that both screw in to and then you can open the valve. Both say they are propane/butane mixes and are for screw on camping stoves.

Any tips on how to do this? Will the larger bottle be at a higher pressure? Or should I rely on Charles' Law and put the little bottle in the freezer first?

[Bearbonesnorm]

Little one in freezer big one in a little warm water. Do weigh the small one as you're filling it, it's quite easy to overfill.

[Wotsits]

Put the big one on top (& upsidedown) so liquid passes over rather than gas..

[thenorthwind]

Put the big one on top (& upsidedown) so liquid passes over rather than gas..

This (and what Stu said), liquid being the gas, and the gas air, though the gas (air) is passing the other way to make room for the liquid (gas). Clear?

[yourguitarhero]

Yeah, I know what you mean! Liquified gas etc

[yourguitarhero]

OK, all seems good! My 166g bottle (160g bottle tare weight according to Primus' website, 6g of liquid gas) is now sitting at 390g which is 230g of liquid gas and a 160g bottle which is spot on.