Originally Posted by DeerHunter
It's reading 500+ PSI which is at least half full. Although I noticed that if I loosen the regulator of the CO2 tank just a bit, pressure on the high side reading goes up again (with no leaks).
Get your point with the small tanks, just wanted to try kegging before I open the wallet for a big tank.
A couple things:
1) At room temperature CO2 goes from liquid to gas at 870 psi. A reading of 500 PSI does not mean you are ~~ half full, it means you have no more liquid in the tank, that is just gas pressure, which indicates you are almost empty. IOW, the pressure will remain ~ 870 PSI, and the liquid level will go down as it changes to gas, until no liquid is left. Only then does the pressure drop. This is why CO2 tanks are filled by weight.
2) Tell us more about the adapter. I suspect that it isn't fully opening the valve to the tank (IIRC, SodaStream tanks have some proprietary fitting and built in one-way valve), So you just have some gas in the regulator, and a s soon as you open the output, that gas is 'used up', and if the gas from the tank isn't flowing, the pressure will drop.
You see basically the same thing on a regular tank set up if you open and then close the tank valve. You can draw off CO2 at the output side, but in a short time the high side pressure falls, as it isn't being re-filled from the tank. I bet you get some CO2 out of your bottle when you put the adapter on, but then the valve isn't staying open, so that's all the gas you get.