Shadyapex
Senior Member
This is the safety warning from Outback Air, and I think it's worth reading as summer cab temps can reach 160F and it also addresses the phase change differences at different temps/pressures.Wallowa said:ntsqd,
Very interesting. You are you saying that when his CO2 tank is filled to the 100 psi rated pressure it goes from a gas to a liquid inside the cylinder? Wow, I had no idea that such a low pressure could transform CO2 gas into a liquid. Very interesting.
Thanks for insight,
Ps...I just re-read the Outback specs on the cylinder charging...they fill to 100psi 'cold' [no mention of temp] and then state that at 70 F the pressure is 837 psi....not certain how all this folds into the possible phase change for gas to liquid.
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CAUTION! – Please Read This Carefully!
A CO2 cylinder is filled with liquid CO2 by weight. At the time of fill the temperature of the charge is extremely cold and the pressure is around 100 psi.
When a fully charged CO2 cylinder warms up to room temperature (70 F), the pressure inside the cylinder increases to 837 psi.
When the same cylinder reaches 87.9 F the entire charge becomes a gas no matter what the pressure. A fully charged CO2 cylinder at 87.9 F will have an internal pressure of approximately 1100 psi.
At 120 F the same cylinder will have an internal pressure of nearly 2000 psi. This cylinder at 120 oF now has an internal pressure greater than the marked service pressure of a cylinder that is properly filled, not overfilled.
At 155 F the same cylinder will reach a pressure of 3000 psi, a pressure great enough activate the safety vent on the valve, venting the CO2 charge.
I fill mine in the fall when ambient temps are low so that by summer when I've been exploring the desert all winter the charge is lower. Hopefully this will avoid filling my cab with CO2 on a hot day, it has so far and I've been doing this for about 5 years. Your mileage may vary.