Author Topic: Strange draft problem: Foam/Gas pocket forming in line  (Read 2227 times)

Offline beer_crafter

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Strange draft problem: Foam/Gas pocket forming in line
« on: August 14, 2017, 03:04:14 AM »
I'm dealing with an issue with one of my draft lines that I've never seen before in all my years of using corny kegs.

When you pour the beer, the first ounce or so is normal*, followed by a gas pocket, followed by a bunch of foam as the line clears.  Once the beer pours from the keg itself, it seems to be fine. 

- It's a ball lock keg that has been in service for a while.

- CO2 seems to be coming out in solution in the lines.  If I pour two pints within a few minutes, the second one doesn't have a gas pocket, but it still does have a good shot of foam. 

- This has happened to me on 2 batches in a row, although I did use the same keg and same lines and faucet each time.

- The beer in question is a brett saison, and I do carbonate it highly.  I don't think this is simply a situation where CO2 is coming out of solution due to some sort of balancing thing.  If I disconnect the line from the keg, the line doesn't foam. 

- I've changed out the black liquid disconnect with no difference.

- I've tried a picnic tap with the same results.

- I keep the beer (as all beers) at 45F.  I keep this one at 14 PSI, on the high side. 

- There don't appear to be any gas leaks and there are definitely no liquid leaks.

Anyone ever see anything like this?  I'm going to take apart the keg and replace the seals if I can't figure out the deal before the keg kicks.

Offline Stevie

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Re: Strange draft problem: Foam/Gas pocket forming in line
« Reply #1 on: August 14, 2017, 03:18:26 AM »
What vol of co2?

Offline beer_crafter

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Re: Strange draft problem: Foam/Gas pocket forming in line
« Reply #2 on: August 14, 2017, 02:20:52 PM »
2.3-2.5. 

Offline Stevie

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Strange draft problem: Foam/Gas pocket forming in line
« Reply #3 on: August 14, 2017, 02:30:09 PM »
You said highly carbed, that CO2 volume is pretty much normal. Could be something stuck in your poppet or in the QD.

Offline kramerog

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Re: Strange draft problem: Foam/Gas pocket forming in line
« Reply #4 on: August 14, 2017, 06:00:12 PM »
Did you previously fast carb the beer at high pressure?

Offline beer_crafter

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Re: Strange draft problem: Foam/Gas pocket forming in line
« Reply #5 on: August 15, 2017, 01:07:27 AM »
Re: Something stuck in the poppet-- Possible.  I do take my poppets apart after each beer while I'm cleaning the keg.  Still, it's possible (and one of the more likely explanations) that there is something wrong here... possibly with the gasket.

Re: Fast force carb:  Yes, but I've done that a couple hundred times and never had this problem, and now have had it in back-to-back kegs.

I guess one thing I hadn't considered until now is a problem with the regulator or gas pressure guage.  Perhaps I have a lot more CO2 in solution than it appears. 
« Last Edit: August 15, 2017, 01:30:38 AM by beer_crafter »

Offline Stevie

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Re: Strange draft problem: Foam/Gas pocket forming in line
« Reply #6 on: August 15, 2017, 01:36:02 AM »
Best bet is unbalanced pressure.

Offline beer_crafter

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Re: Strange draft problem: Foam/Gas pocket forming in line
« Reply #7 on: August 15, 2017, 02:47:25 AM »
In theory, shutting the gas and degassing this over time should then correct the problem  (or at least indicate that overcarbed was the cause).  Let's see. 

Offline el_capitan

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Re: Strange draft problem: Foam/Gas pocket forming in line
« Reply #8 on: August 15, 2017, 04:14:32 AM »
Best bet is unbalanced pressure.

+1  That was my initial thought, too. 

Offline beer_crafter

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Re: Strange draft problem: Foam/Gas pocket forming in line
« Reply #9 on: August 17, 2017, 11:13:01 AM »
Seems like the problem was somewhere between the poppet, the gasket on the dip tube, and the keg itself.  I used Keg lube all over these connections.. I really lubed it up   8) and seems to have fixed the problem.  I think the system was sucking some CO2 out of the headspace in the keg. 

Offline beer_crafter

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Re: Strange draft problem: Foam/Gas pocket forming in line
« Reply #10 on: April 08, 2018, 02:17:10 AM »
Just to follow up, I haven't quite licked this problem.

It's with only one of my taps-- I've replaced the faucet to no avail.  It has happened with 2 different kegs. 

This tap does get my funky and sour beers, and I like to serve them at high pressure.  I think I've been overcarbonating the beer and then lowering the gas as the keg gets lower and then I'm unbalanced.  The keg pours fine for the first 1/3 to 1/2 of keg... once the level gets low, I start getting CO2 in my lines. 


Offline Phil_M

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Re: Strange draft problem: Foam/Gas pocket forming in line
« Reply #11 on: April 08, 2018, 02:28:54 AM »
One of my taps just did this on the beer I'm currently pouring. First time I'd seen that. Pouring foam, then nothing, then foam, then beer.

My guess is there's a warm section of line, and enough CO2 comes out of solution to create an air pocket. I've always had issues with warm lines pouring foam for a bit, but this was the first time that there was a noticeable stop in flow, then it started again from a bubble.

Don't know if you've got the same issue or not, but it would pass occam's razor more easily than something stuck in a poppet valve.

Kinda similar to how a vapor pocket can form in a warm fuel line.
Corn is a fine adjunct in beer.

And don't buy stale beer.

Offline beer_crafter

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Re: Strange draft problem: Foam/Gas pocket forming in line
« Reply #12 on: April 12, 2018, 06:03:21 PM »
My lines are in the fridge... there would have to be quite a gradient in temps for that to be the cause... haven’t ruled it out though.

Offline Phil_M

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Re: Strange draft problem: Foam/Gas pocket forming in line
« Reply #13 on: April 13, 2018, 02:46:26 AM »
My lines are inside the fridge as well, but despite the tower being insulated I've long suspected the lines are getting warm in it.
Corn is a fine adjunct in beer.

And don't buy stale beer.