Re: [A/S] One more Propane answer

[Jim Dunmyer <jdunmyer@xxxxxxxxxxx>]

Tom,
  That's not the way LPG works at all:

All LPG is a mixture of gases, as someone else pointed out; it's mostly 
propane and butane. What we're calling "propane" is more properly called 
LPG.

The LPG in your tanks turns from a liquid to a vapor, (think "boiling") 
causing pressure. The pressure will vary with the ambient temperature, 
going from zero at -40 degrees F or thereabouts to 100 PSI or more on a 
hot day. As you draw gas from the top, the remaining liquid boils to 
replace that gas, cooling the bottle in the process. Remember, you must 
add heat to make any liquid boil; witness your teakettle.

Because of the vairable pressure, a regulator is required to "step down" 
the pressure to something useable by your appliances. That's the little 
gadget between your cylinders, and it takes the incoming gas, at 
whatever the pressure is according to ambient temperature, and steps it 
down to 11" WC, or just a few ounces/square inch.

Shaking a propane tank to generate pressure is sometimes done, but 
what's happening is that the liquid is exposed to more surface that's 
(hopefully) warmer. The shaking itself has little to do with it.

                               <<Jim>>