Entity pensioner spoke thus:

> I think the vapor pressure of Propane/LP gas depends only on temperature and
> not on volume of liquid in the tank.
Blah blah blah...

But when you buy "propane" it as actually a blend of hydrocarbons depending
on the quality of refining. Of course the first to boil off are the lighter
molecules (ethane, propane) and what you are left with on the bottom are the
heavy ones (butane, pentane), then in cold weather you are cursing because
you need to warm up the tank to get the flame out of the gas! That is about
when you put the tank ON TOP of the flame!

Rachel http://www.gnarlodious.com