Foamy pours can be an incredibly frustrating experience, and trying to figure out (and fix) what's causing them can be just as infuriating. This is something we went through recently so read on to find out the steps we took to troubleshoot and fix the foamy pours that suddenly started happening with our kegerator system.
Introduction
We recently faced a situation with our Hard Seltzer that had been working perfectly in our kegerator system for a couple of months. In a previous post, we outlined the setup we used to adjust for the increased carbonation level of the seltzer, with significantly more carbonation and serving pressure being used compared to beer.
The Problem
All of a sudden, the seltzer started pouring as nothing but foam. Not foaming as it left the tap and arrived in the glass, but rather coming out of the tap already as foam. Looking at the line itself coiled within the kegerator, we could see foaming, or gas escaping out of solution in there before it had even reached the tap. This was a first clue as to what the problem was.
This was puzzling as nothing had changed within the kegerator at all when it started happening. We hadn't adjusted anything, or even changed a keg over, it literally started happening completely out of nowhere.
Not a Line Balancing Issue
If you start researching beer (or seltzer) foaming issues from a kegerator, you'll come across the same solutions repeatedly - over carbonation and not having your system or lines "balanced", which means having enough resistance in the serving line to avoid the carbonated CO2 gas coming out solution rapidly which causes foaming.
We knew that these solutions didn't apply for this particular scenario as it had been pouring perfectly for several months with our increased line length and flow control disconnect.
Initial Troubleshooting
We spent more time than we'd care to admit changing disconnects, lines and attaching different things to different kegs to try and isolate the problem. We eventually settled on the problem being with something related to the keg itself, and after much researching we finally found a thread on a homebrewing forum from someone who experienced a similar problem.
In their case it ended up being caused by a faulty dip tube seal on the keg ball lock liquid post. This seemed like a plausible scenario for us, and would explain the bubbles/foaming we're seeing in the beer line itself. A faulty seal can lead to air being let into the gas lines at the keg post or disconnect which can cause this foaming to occur.
Our kegs are a couple of years old now and we've never changed the seals so we figured this was a worthwhile thing to try - after all, o-rings for keg dip tubes and ball lock posts are pretty cheap and easy to come by from most homebrewing shops so we figured it was worth a shot.
Changing Ball Lock Post Seals on a Corny Keg
Undoing the ball lock post from the keg is thankfully a really simple process - with a 17mm spanner being all that's required to undo the post. Here are the steps.
1. Make sure you de-pressurise the keg by pulling the PRV to vent all the gas in the headspace. Removing a post with the keg under pressure will turn the post and dip tube into a missile that could cause serious injury.
2. Unscrew the post using the 17mm spanner and remove it. Be careful not to let the spring and poppet fall out once you remove it.
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| Liquid ball lock post o-ring |
3. The dip tube can now be pulled out so the O-ring is accessible.
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| Dip tube o-ring with dip tube slightly lifted |
4. You can now remove the O-ring by sliding it down and off the end of the dip tube.
5. Install the new O-ring by sliding it down from the end of the dip tube back to the top.
6. Re-insert the dip tube back into the keg, be sure to orient the slight bend towards the end of the tube so it's angled in towards the centre of the keg.
7. While you're at it, it's a good opportunity to replace the seal on the ball lock post as well.
A Note on O-Rings
We carefully inspected both of the used seals after replacing them, and to our eye they looked fine, but there was obviously a defect in there somewhere that caused this problem to occur. It just goes to show that even the slightest of imperfections or defects in the seal itself can have a significant impact on the pours from the keg, so a visual inspection isn't always going to tell the full story.
Conclusion
We suspect that the O-ring on the post itself is the more likely culprit here, rather than the one on the dip tube as this is more susceptible to damage and wear and tear from the repeated connecting and disconnecting of ball lock disconnects.
In any case, it was apparent that a leak in one of the O-rings was letting air into the beer lines which was causing the foaming to occur.
It's important to be patient when putting things back together and testing. Since we obviously had to purge the keg of all pressure prior to removing the ball lock post and dip tube, this would have caused some foaming within the keg, so after reconnecting everything and pressurising the keg again, we waited a couple of hours for things to settle before doing some test pours which were thankfully foam free!
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