Originally Posted by Gunfighter04
Even when considered full, the CO2 in liquid form in your tank is only about 40%. Most won't go above that due to liability from rupture.
not exactly, but it the point is moot because they go by weight of CO2 and not volume. 5lb in a big tank is the same as 5lb in a small tank; only the small tank would have a greater % of liquid in it. doesnt have anything to do with rupturing, as its all the same pressure. you cant overpressurize a CO2 tank unless you either; forcibly pump more liquid CO2 in then it can hold, or heat the tank so that the gas-to-liquid transition pressure gets to a point that will rupture the tank.
CO2 will convert to liquid, at room temperature, when its around 1000 PSI, +/-. when the pressure of the gas drops, the liquid will gassify to maintain the same pressure. when the pressure goes up, some gas will liquify to maintain that pressure.
when you refrigerate the whole tank, that gas-to-liquid transition point will get lower according to gas laws mentioned above.
this is the reason that your high pressure gauge will read almost the same for a very long time, and then suddenly start to fall to "E". that is because the liquid CO2 maintains a constant pressure until it runs out of liquid, then the pressure rapidly falls when all that remains is gas.