On refilling your own propane bottles:  Propane, unlike water, has a
moderately high coefficient of expansion in it's liquid state. This means
that the liquid expands a lot with temperature and can rupture bottles or
fuel lines easily unless there is head room within the bottle or
container.  Basically, liquids do not compress!! The 1 pound cylinders
have a pressure release valve built in which will release propane unless
the bottle has the required 20% head room space. And this assumes that
the bottle will not get excessive hot.  Larger, outside propane cylinders
are painted white for a reason, Coleman's are dark green. If you are
pulling up on the pressure release on the 1 pound bottles until a liquid
appears, you are not leaving room for liquid expansion and the bottle will
vent gas (providing the safety valve is working correctly).

FWI - It vaporizes at -44 degF (that's why it freezes your fingers),
weights 4.24 pounds per gallon (temperature unknown, 60 degF I think), and
contains 91,650 BTUs per gallon.  A liquid gallon produces 270 gallons of
vapor, which is heavier than air. All at a home delivered rate approaching
$1.50 per gallon for 4-500 gallons.

Sorry for the lecture, but I want our Westies (and their owners) to stick
around a while longer.

Tom Goff - 1984 full Westy - original ower, 88K miles - Highland, MD