Can Pressure Affect Temperature?

[chefschipull]

I read somewhere that the colder co2 gets, the lower the pressure will read on the regulator. If that is true, is there any way to tell how much co2 I have left in my tank? When it is filled up, it only reads at 500 psi, which is low considering the gauge goes up to 3000 psi.



- ChefSchipull

[topgun3208]

It is true, a cold co2 tank will yield a lower reading. I have a 5# internal tank which will read 500psi after filling, and you can get quite a few 1/4 barrels out of it. when the needle starts dipping into the red, it is time to replace it, it goes rather quickly. being a welder, I know high pressure cylinders are NEVER filled to "gauge" capacity.

"If I had to live my life over, I'd live over a saloon"

[Scott Zuhse]

A correctly filled CO2 cylinder @ 70 degrees F environment has approx. 850 PSIG gas pressure. This CO2 consists of 68% liquid with the head space gas. The cylinder will exert this pressure until all of the liquid is gone. This is when the high pressure will begin to drop and when it reads below 500 PSIG the cylinder is almost empty. Good practice is to change the cylinder at this time to prevent the regulator from self adjusting.

If the environment changes such as placing the cylinder inside the kegerator, the cylinder PSIG will be lower and read below 500 until again the liquid CO2 is displaced. Same amount of gas but more difficult to determine when the cylinder is empty. A tip on adjusting the regulator on a cylinder placed in a kegerator is to allow the cylinder to acclimate first prior to adjusting.

Scott Zuhse, Instructor Micro Matic Dispense Institute