CO2 Bottle PSI drop in Keezer?

[BendBrewer]

I am dealing with a leak in my CO2 system in my keezer. After blowing through a bottle after 4 corny kegs and another 1 keg later, I brought out the old soapy water and found a leak in one of the lines and fixed it.

I checked all other connections and didn't notice any other leaks, so I placed the new CO2 tank in the keezer and hooked it up to the only keg that is ready to drink.

After racking another batch into a keg, I checked the regulator and noticed that the pressure seemed to be dropping a little. Checked it again a little later and yeah, the pressure did drop from 700ish PSI to close to 600.

Frustrated, I poured myself a beer and shut the bottle off assuming I still have a leak even though I feel I had checked everything.

But, would the fact that I was cooling the CO2 tank down by moving it from room temp to the inside of the keezer effect the PSI reading?

Has anyone else noticed a perceived drop in PSI by chilling their new CO2 bottle or do I still have a leak somewhere?

 

[wildwest450]

But, would the fact that I was cooling the CO2 tank down by moving it from room temp to the inside of the keezer effect the PSI reading?

Ding, ding, we have a winner. The psi will drop dramatically when chilled. If the leak is fixed, you should be fine.


.

 

[Special Hops]

PV=nRT

P - pressure
V - Volume
n - amount of actual gas
R - gas constant
T - Temperatur
V, n, and R are constant in your cylinder,

which means that pressure is related to temperature. So when you drop the temperature, your pressure will go down, even with the same amount of actual gas.

 

[Ohio-Ed]

Its actually more complicated than that... co2 is in liquid form so your pressure gauge will read almost the same until basically the liquid in the tank is gone. You can't really use the pressure as a sliding scale of how much co2 is in the tank. It will drop very quickly when the liquid is gone. The only way to really know how much co2 is left is by weight.

 

[Special Hops]

Its actually more complicated than that... co2 is in liquid form so your pressure gauge will read almost the same until basically the liquid in the tank is gone. You can't really use the pressure as a sliding scale of how much co2 is in the tank. It will drop very quickly when the liquid is gone. The only way to really know how much co2 is left is by weight.

good point.

 

[senorswiss]

I couldn't find the table I was looking for, but this vapor pressure chart is more informative anyway. http://www.teamonslaught.fsnet.co.uk/co2pv.gif

Taken from the page: http://www.teamonslaught.fsnet.co.uk/co2_info.htm

You can see the gauge pressure remains constant (for a given temperature) while there is still some liquid CO2 left.

 

[Bubba_Mustafa]

I've seen a bottle or two leak at the bottle's valve. Its best to open then fully and 'backseat' them.

(its rare, but happens, like getting a bottle of bad gas or miss-labeled gas)