"Scott Rogahn" wrote in message
...
CO2 becomes a liquid at about 800 psi. At less then 800 psi the liquid will
boil off until the pressure in the bottle reaches 800. So as long as there
is liquid in the bottle the pressure will read 800. Regardless of weather
the bottle has just a little liquid CO2 or is completely full. You can tell
how full the bottle is by weighing it. Off course you will need to know the
empty weight first.

The tare weight (empty weight) is normally stamped on the cylinder, so
you can find out fairly easily how much CO2 is left by weighing the
cylinder. (The tare weight doesn't include the weight of the regulator,
but you can adjust for that at least roughly.)

Cheers,

Michi.

--
Michi Henning Ph: +61 4 1118-2700
ZeroC, Inc. http://www.zeroc.com