Corny Keg Fermentation Leak

[John Spiegel]

Fermenting under pressure in a corny keg. Filled up to the weld, pressurized to 10 psi, attached spunding valve, and let sit overnight. By morning, pressure was at 0. I checked for leaks with star san and there were no bubbles. Tightened gas and liquid post, re-seated the lid, even went through and reconnected all the hoses to the butterfly spunding valve. Couldn't find anything wrong, but I seem to be losing about 2 psi an hour. I've re-pressurized from my CO2 tank, but I don't want to keep doing that, and I'm also worried about a long, slow leak losing a lot of gas.

Any clues where the leak could be/how to find it? Eventually, when fermentation kicks in, will it be putting out enough pressure to counteract that leak? I'm only 12 hours since pitching right now.

 

[Golddiggie]

The CO2 you pushed in is getting absorbed by the liquid inside the keg. IMO, stop doing that. Let the yeast CO2 production pressurize the keg.

 

[John Spiegel]

The CO2 you pushed in is getting absorbed by the liquid inside the keg. IMO, stop doing that. Let the yeast CO2 production pressurize the keg.

Ok. I was wondering if that was a possibility. I knew yeast would use oxygen, but wasn't sure about CO2 getting absorbed, especially at such a warm temp.

 

[Golddiggie]

Liquids absorb CO2 when it's put in under pressure, which you've been doing. Same as for when you carbonate in keg. Having it warmer just means you need MORE CO2 pressure to get the same carbonation level you would at a lower temperature. Doesn't change the physics of things.

 

[odie]

what is happening is the wort is absorbing the headspace pressure and then the lid o-ring can sometimes "un-seat" once psi drops to just a point or two.

Just don't mess with pressurizing the keg. fill, pitch yeast, set spund valve, walk away.

Once fermentation starts up, the wort will absorb the CO2 being created and any excess will get gassed off into the head space. Soon it will gas off faster than an un-seated lid o-ring can vent it and then the o-ring will seat if it wasn't seated already. psi will climb until the spund valve setting is reached and the excess will spund out.

some lid o-rings will seal without any pressure. some won't. just how it is. keg lube is your friend.