Keg liquid dip tube losing siphon

[TSMill]

I assumed nobody would look at "help my beer is foamy!", so gone with a slightly speculative title. So here's the deal.

I have one key that consistently pours foam. When it has been sitting idle for a while, there is gas evolving in the beer line, for perhaps a 10cm length. I run 3 taps in a fridge with 4 kegs, so I've swapped around keg location, taps etc. and everything else works fine. I carbonate slowly at serving pressure, so know the keg is not over carbonated (that is, it is carbonated to the same level as all other kegs).
There is not an external leak from the keg post, I've checked with starsan spray, plus the pressure has been holding up for a couple of months. I'd say this has happened with this keg as least the last 2 times, so it is not specific to this batch of beer.

I've narrowed it down to 2 possible options, but am open to others.

1. There is some point of roughness/nucleation on the keg outlet post, which is causing the gas to come out of solution faster than desirable as poured, or:

2. There is a leak on the keg liquid post/dip tube internal to the keg, which is breaking the siphon when sitting idle (hence, gas sitting in beer line), and allowing excess gas to enter the beer stream when pouring.

Personally, I'm leaning to option #2, as I do not think #1 would cause that much gas break out in the beer lines. Just wondering if this is a problem anyone has come across in the past, and any thoughts on a possible solution?

Oh...and yes I have pulled the keg apart and could not see anything untoward.

Cheers

 

[pcqypcqy]

Re point 1 - i've had this happen with poorly filtered hoppy beers, a bit of hop matter got stuck in the poppets and caused nothing but foam.

Point 2 should be easy enough to check, pull the keg apart, put your finger over one end, blow on the other. See if it holds pressure or whether you can hear a leak.


I too have been having some issues where I can see gas accumulating in the beer lines, not quite sure what is happening here but haven't looked into it too much. Will be keen to see what your solution is.

 

[malt junkie]

Re kit, caustic clean

 

[damoninja]

I have this happen with a particular beer that I brew, I put it down to the proteins in it or something as it's done it over more than one brew but the same keg / lines and so on have been otherwise OK.

If I don't want a glass full of foam I have to drop the pouring pressure right back, even when the carbonation is relatively mild.

 

[TSMill]

It is a hoppy beer so will look into the poppet theory. As I said keg is a repeat offender but maybe I got unlucky twice.

Tried blowing down the dip tube but don't think I generate enough pressure for that to be a definitive test.

 

[mofox1]

I've had this twice for two different reasons. First one was the seal at the top of the dip tube wasn't quite perfect... Can't remember if it was a slightly too long dip tube, or out of round at the top, both seem to stick in my mind... The other was the spring in the post was far too stiff vs the spring in the disconnect, meaning the poppet wasn't depressed fully.

 

[mstrelan]

Did you try swapping the post and dip tube with another keg? If that fixed it replacement posts are cheap and dip tubes are about $20.

 

[contrarian]

I've had a keg that did this but it would always start blowing foam after pouring some beers that were fine. Turned out there was a small hole in the beer dip tube that was the culprit but that was fairly evident from a visual inspection.

 

[pcqypcqy]

It is a hoppy beer so will look into the poppet theory. As I said keg is a repeat offender but maybe I got unlucky twice.

Tried blowing down the dip tube but don't think I generate enough pressure for that to be a definitive test.

Maybe try using it as a straw. Beer would work best, for you know, accuracy reasons :chug:

 

[user 37368]

Over carbonating can cause this too, the top of the keezer is slightly warmer than the bottom and some nucleation occurs at the keg end of the beer line.

 

[Cosh]

Had this happen ages ago. Add another o-ring to the top of the dip tube.

 

[TSMill]

Ok, partial credit for the hop pellet in the poppet. Cleaned that out plus replaced the dip tube o ring. Still not a great pour but vastry improved. Thanks guys.

 

[pcqypcqy]

Ok, partial credit for the hop pellet in the poppet. Cleaned that out plus replaced the dip tube o ring. Still not a great pour but vastry improved. Thanks guys.

Yep. It happens.