Keg Leak -- without Leaks?

[Johnny5]

Hi,

I've got a vexing kegging situation I was hoping someone might be able to diagnose:

Basically, I just got my two-corny kegging system back up and running after (too long) of a delay. I exchanged my old 10lb CO2 tank that was almost empty, replaced the lines, poppets, etc. I did an initial test before racking beer into the kegs. Did the soapy water test on all the fittings. Fine. No bubbles.

So, I racked my beer last night and on the advice of a local brew shop, pumped the system to 30PSI to do a force carbonation process over a few days to bring it down to about 6PSI. After doing this last night, I did another soap test, no hisses or bubbles. Great.

So, this morning I get up and my brand new CO2 tank has dropped from about 800PSI to about 300-400PSI on the gauge. So, I figured I must have a leak. I did a third round of soap tests and listened for leaks. Nothing. I tested CO2 canister fittings, poppets, dispenser ends, everything.

Now the only thing that I wonder about is about the accuracy of the tank readings. I thought I'd heard that it's not the absolute best to put the CO2 tank in with the kegs into the refridgerator, but could it affect the pressure or readings that much? I didn't have a scale to weigh the tank when I got it, but it still seems pretty heavy as far as I can tell. Also, the pressure actually went up from 30PSI I set on the gauge last to about 32 this morning, so it's remaining pretty steady there and not losing pressure. And the beer kegs seemed to have good pressure when I tried the release valves, although I could hear the beer sloshing around when I moved the kegs. Isn't it supposed to pressurize the beer so you shouldn't hear it swishing?

Anyhow, any input? I don't know what else to do.

Thanks!

John

 

[Funkenjaeger]

When you put a co2 tank in the fridge, its gas pressure will drop dramatically, to about the pressures you are seeing. This in no way affects the operation of the regulator as it's still more than high enough input pressure, and in no way affects the amount of CO2 you will get out of the tank.

In short, CO2 is mostly liquid in the tank, with a small amount of it as high-pressure gas. The pressure of the gas is determined by the temperature (partial pressure) so it changes dramatically. It's also unimportant, because the tank pressure will remain constant (for a given temperature) until ALL of the liquid CO2 has been used up, at which point the tank is VERY close to being empty, and then the gauge will drop rapidly within a handful of pints - so really, the gauge serves no purpose other than as a possible last-minute warning when your tank is almost empty.
You're not the first person to get paranoid about it, if you do a search you'll see lots of threads with the same thing.

New dual-gauge regulators ought to come with a little sticker covering up the tank pressure gauge, with a disclaimer along the lines of "do not remove this sticker until you understand that tank pressure will dramatically fluctuate with temperature"

 

[Johnny5]

Hey, Funkenjäger,

Wow, thanks so much for the reply. That certainly is a load off my mind. Yeah, someone told me once not to pay too much attention to the main pressure gauge as far as how much CO2 is left, but this kind of sudden drop off seemed pretty drastic since it was skirting the red level.

Thanks again for the help. I'll be sure raise a toast to you when I bust out my altbier soon!

John