Less volume with a cold CO2 tank?

Just refilled my co2 tank and put it in the fridge with my keg, now it's showing less volume than before, is it just because it's cold and the molecules are not moving as fast, because I know gasses expand when warmer. If not I have a leak.


Thanks

The pressure will be lower when it's cold as more of the CO2 stays in the liquid phase and doesn't contribute as much pressure. That's why the high pressure gauge is relatively useless when you keep the tank in the fridge.

pressure is directly proportional to temprature

at 36degrees i get about 550psi
at 70degrees i get about 800psi
at 90degrees i get about 1000psi

It's not a volume guage. It's a pressure guage. It's measuring the amount of pressure of the co2 gas in the container. There is also liquid co2 in the tank. When you use the some of the gas, some of the liquid evaporates to take it's place. When all the liquid is gone, only then will you see the high pressure guage begin to drop. That means your tank is nearly empty, and you need to refill soon.

The high pressure guage is just as effective inside the kegerator as it is outside the kegerator. Either way, it tells you that you have co2 left. The only way to determine how much co2 you have left is to weigh the tank.

Put the tank on a scale and you can find out how much is in there. As all the other guys already mentioned ... it doesn't show the right numbers due to the cold

As the others have stated, CO2 in a liquid/vapor state has a direct pressure/temperature relationship, as can be seen in the chart below. The pressure will stay the same, at a given temperature, until all the liquid has been vaporized. Once only vapor exists, the pressure in the tank will drop rapidly.

yermej said:

The pressure will be lower when it's cold as more of the CO2 stays in the liquid phase and doesn't contribute as much pressure. That's why the high pressure gauge is relatively useless when you keep the tank in the fridge.

Click to expand...

Then ss the low pressure gauge not accurate either if the tank is in the fridge? I just kegged my first batch and keep my tank in the fridge, so im wondering when I keg my next batch if I will need to take the co2 tank (I have two low pressure gauges for two separate kegs) and let it warm up to room temp in order to set the volume of co2 to where I want it for the new keg?

Beerme01 said:

Then ss the low pressure gauge not accurate either if the tank is in the fridge? I just kegged my first batch and keep my tank in the fridge, so im wondering when I keg my next batch if I will need to take the co2 tank (I have two low pressure gauges for two separate kegs) and let it warm up to room temp in order to set the volume of co2 to where I want it for the new keg?

Click to expand...

Actually, I haven't thought about that. From my experience (I keep my tank in the fridge), the low pressure gauge seems to work fine. I'm guessing that it's accurate because it's dealing with CO2 gas and not the gas/liquid combination that's in the tank. Maybe somebody else knows more about what actually goes on?