CO2 question

[joe_r_harvie]

Hi, I just kegged 15L into a 20L corny keg. When the gas started going in the keg, beer started running in one of my other gas lines??? I have 3 air lines running off one regulator. Not sure what happened as this has never happened before. FYI: 15 L is the smallest batch I've ever put in a keg; My CO2 is getting low but not empty; this happened once when I had the gas going in the out side (not the case this time). Any idea what happened?

Thanks - Joe

[chalmers]

Hi Joe, so as you were pressurizing keg #1, beer from keg#2 was flowing up its Gas In line, back towards to regulator?

It's probably because there was a temporary pressure differential, as keg#1 was at atmospheric pressure, whereas keg#2 was at a higher press, and flow goes from high to low pressure.

A few things you can do to avoid this:
1) Cut the "diptube" of your Gas In line shorter
2) Do not fill your kegs above the Gas In line
3) Lean keg#2 so that the beer is not near the diptube while you work on keg#1. After the pressure has settled a bit, you can set it back down.

All three of these situations are not ideal, as it proves that there is some sharing of gas (and possibly liquid!) between kegs, which can mean an infected beer could ruin others hooked up at the same time.

Better ways to deal with this:

4) Use checkvalves (one way valves) on your gas lines, so the CO2 (and beer!) can only flow one way: regulator to keg Gas In line.
5) Use shutoff valves on your gas lines: when first filling a keg (and then purging it), turn off the other kegs, so they are isolated from the temporary big pressure fluctuations
6) Remove other kegs from the CO2 temporarily while you purge/fill your kegs with CO2

Of course, only #4 fixes the gas mixing issue, but 5&6 avoid the beer flowing the wrong way.

Hopefully the beer didn't get too far up and gummed up your regulator.

[joe_r_harvie]

Thanks very much Chalmers. That answers my question. Much appreciated. - Joe