Leaking CO2 from liquid post via tube. Is this possible? Is it the cause of all-foam pours?

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Awnry Abe

Feb 3, 2022
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Nube kegger here. I am onto my second keg, and have been battling over foamy/under carbonated beer for a little over a week on it. I am still building out my system and have yet to make permanent taps. My system is extremely simple at the moment: Just the C02 tank, regulator, 1 line, 1 keg, 1 picnic dispenser, all in the keezer. The first keg is still in the fridge. It's almost empty, and I had no carbonation or dispensing issues with the exact same set of hoses. The dispensing hose was only a foot long with a picnic tap on the end. Beer from the second keg is coming out like shaving cream. Many google searches suggested my tiny dispensing hose was possibly the cause of the foamy pours, so I made one 12.5 feet long--this time using duotight fittings. I learned a very important first lesson on duotight fittings as the new dispensing hose drained my CO2 tank overnight. I check the gauge every time I open the door because I've been paranoid about leaks. It really hasn't budged much since first use. Literally all I did to go from full(ish) tank to empty overnight was that new poorly-constructed dispensing line.

My question: Could the beer post on the keg be leaking C02 internally from the head directly into the dispensing line? Bad or poorly seated O-ring on the inside tube perhaps? Or did I knock something loose from tank to keg when banging around in the keezer and not realize it? I would have expected a freezer floor of beer, but there was only a small drip. Could this also be the cause of the full glass of foam on pour?

(For the curious, going from 1 ft to 12 ft half-solved the foam problem. I could get a half a glass of beer.)


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Aug 3, 2006
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Whitehouse Station, NJ
Yes, if you're getting aggressive foam in the line right out of the keg and you're sure you didn't grossly overcarbonate the beer, I would look at CO2 getting in to the liquid path. There are two ways this happens. One is a pinhole in the keg's long draw diptube. I've seen this twice in 15 years. The other is something to do with the drawtube oring under the post. It's also quite rare to have an issue with this oring that lets co2 into the liquid path but doesn't allow gas to leak out of the keg. It would be due to a piece of debris, hair, etc or a nick in the oring in just the right place.

The way you diagnose if you have one of those situations is to lay the keg on its side with the liquid post closer to the floor. If the foam stops, one of those two things is your problem.