Head scratching keg issue

[Dmaudsley34]

Hi peeps, I’ve recently run into a foaming issue with one keg/beer.
It’s been fine till about halfway down, now just foam.
1. I’ve stripped and cleaned the tap
2. Liquid out post has been replaced
3. Line checked and rechecked for leaks
4. Offending keg continues to offend on the thetap
5. Behaved keg works on the offending keg line
6. Gas at 12-15psi for both beers
7. Kegerator temperature at 7c
When connected up and the tap is open there are noticeable large bubbles in the line which periodically change to a sudden rushing sound. Could there be a seal failure on the keg? Once tipped upside down there are no liquid leaks.
My apologies for the long post, hopefully I’ve covered most things. I’ve been searching google for hours now so hopefully someone can shed a little light

 

[GilSwillBasementBrews]

Did you try replacing the o rings on the beer out diptube? They’ve been known to go bad and allow co2 into the serving beer from the headspace of the keg?

 

[grampamark]

^^^^^
What he said. Also, check the flare at the top of the liquid out tube, against which the o-ring seals, to see if it is deformed.

 

[Vale71]

Sounds like one keg is overcarbed. Do you by chance have a dual body regulator?

 

[GilSwillBasementBrews]

I would think if that was the case it would’ve been foamy pouring from the start not halfway through the keg.

 

[Vale71]

I would think if that was the case it would’ve been foamy pouring from the start not halfway through the keg.

If the beer is properly carbed and is then attached to a regulator whose manometer shows a much lower pressure than what is actually being pushed into the keg you would expect the beer to increase carbonation as time passess until you're only serving foam, which is exactly the behavior that is being described by the OP.
Those mechanical manometers are worthless, all it takes is a relatively small shock to throw them off permanently.

 

[NitrogenWidget]

^^^^^
What he said. Also, check the flare at the top of the liquid out tube, against which the o-ring seals, to see if it is deformed.

what these guys said.
bubbles in the beer line to the tap was almost always a bad o-ring.
the only other time was when some blueberry got caught in the poppit on my blueberry wheat.

 

[IslandLizard]

When connected up and the tap is open there are noticeable large bubbles in the line which periodically change to a sudden rushing sound.

As mentioned before, that sounds like a leak on the diptube o-ring, allowing headspace CO2 to directly enter the post and line.

 

[grampamark]

If the beer is properly carbed and is then attached to a regulator whose manometer shows a much lower pressure than what is actually being pushed into the keg you would expect the beer to increase carbonation as time passess until you're only serving foam, which is exactly the behavior that is being described by the OP.
Those mechanical manometers are worthless, all it takes is a relatively small shock to throw them off permanently.

Don’t overthink this. I have a single regulator on a 3 tap kegerator. Occasionally, I will find a keg exhibiting the behavior described in the OP. The cause is always a leak at the liquid out seal. Always.

Start with the easy and obvious and work towards the more difficult or uncommon. Saves a lot of time.

 

[Dmaudsley34]

Many thanks for all your responses, I’m going to order some replacement seals for all my kegs as they have all been on for a couple of years. Currently I have a single regulator on with a line splitter so I am aware it’s not exact.

If the beer is properly carbed and is then attached to a regulator whose manometer shows a much lower pressure than what is actually being pushed into the keg you would expect the beer to increase carbonation as time passess until you're only serving foam, which is exactly the behavior that is being described by the OP.
Those mechanical manometers are worthless, all it takes is a relatively small shock to throw them off permanently.

This is what I experience on almost every beer! Any recommendations on an upgrade?

 

[day_trippr]

fwiw, this phenomenon could be explained by a pin hole breach of the long dip tube at the level the foam was first encountered.

Compared to the other possible causes (carbonation creep, damaged out dip tube O-ring, etc) it's a long shot, but there have been at least two instances of this failure mechanism related on this site in the last 10 years...

Cheers!

 

[Vale71]

This is what I experience on almost every beer! Any recommendations on an upgrade?

Then maybe you're just setting the serving pressure too high, regardless of how accurate your reg is. How do you carb your beer in the first place?

 

[Dmaudsley34]

Then maybe you're just setting the serving pressure too high, regardless of how accurate your reg is. How do you carb your beer in the first place?

The gas stays at 12-15 psi the whole time, I just wait longer before first drinking a beer that’s freshly kegged. So initial carbing and serving are handled by the same canister/ regulator and line

 

[seatazzz]

+1 to what somebody said above, replace your o-rings. Especially on the dip tube; if you have at some point ratcheted down too hard getting the post in, that o-ring may be compromised. Even if not, a bit of judicious keg-lubing might help as well.

 

[moreb33rplz]

I bought 4 used kegs a few months back and have had to deal with 2-3 leak issues when they are full of beer. No bueno. I just bought 4 more, and all of these are getting new rubber, poppets, and prv's.

 

[Jim R]

Keg lube is also your friend on your new o-rings.

 

[TheBluePhantom]

Sometimes if the keg is hard against the side it will freeze a bit, the ice in the line rips carbonation out of the liquid. similar results.

 

[k-daddy]

I had a similar problem. I found hop debris in the outpost popit and once I cleared it, everything returned to normal. I always check my o-rings and use keg lube prior to kegging which led me to believe it was the the hop debris causing the problem.

 

[Dmaudsley34]

I had a similar problem. I found hop debris in the outpost popit and once I cleared it, everything returned to normal. I always check my o-rings and use keg lube prior to kegging which led me to believe it was the the hop debris causing the problem.

I’ve just managed to dismantle the outpost and found a fair bit of hop debris, so hopefully that’s solved it! Will be trying again later this evening so fingers crossed.
Also ordered a full set of new o-rings for all my kegs so they are all getting treated to a service.

 

[Dmaudsley34]

Many thanks for all of your thoughts!

 

[TheBluePhantom]

If you pick up debris often you may want to get a screen, or shorten the dip tube. There are also flexible floating dip tubes now.

 

[MikeCo]

If you're using a floating dip tube, the end of the tube may have come out of the beer.