Foam, foam, foam

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jas0420

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Hi all, I hit the bottom of a keg of brown ale last Friday. I had another keg of it from the same batch that has been living outside of the kegerator (in a 72 degree room) since they were originally carbonated (together in the kegerator for several weeks at 10psi).

I pulled out the empty keg, put the full one in the exact same place (kegerator at 36 degrees), hooked it up to the exact same gas line (10 PSI coming from a manifold with other kegs that are pouring just fine), the exact same beer line (5’6” of 4mm EVABarrier), and the exact same faucet Perlick 630SS). The keg and the beer in it are the only thing that changed from what was previously pouring just fine.

I let it sit overnight to cool down and pulled the first pint Saturday afternoon. From the moment it first hits the beer line after leaving the keg, it is foam. It pours a full pint of foam. Over and over. I don’t get it.

Had friends over Saturday and fought with it the best I could. I fully bled off the pressure a few times in case it was somehow high. No change. I tried a randomly longer piece of beer line (probably about 15’) and it barely made it to the end of the line. Barely poured.

I let it acclimate a couple of days and came back out just now to find the same situation. It is probably a little under carbonated when I sample it, but I don’t know if that is from it foaming or if the keg did wind up a little under carbonated back when it was legged (that shouldn’t be the case, but clearly something is somehow different).

Ideas? I can play around with some other lengths of tubing to maybe find a balance, but would like to understand what may have gone wrong... never had this happen before.
 

Jtvann

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When it sat warm, CO2 came out of solution. That CO2 caused the head space pressure to rise significantly. Your beer has to reabsorb the CO2. It will take time … more than 1 night. It will likely take the better part of a week to fully equalize.

By bleeding pressure off, you will have to add more.

Set it and forget it. For sure by 2 weeks time it will be fine.
 

day_trippr

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Alternative explanation: the second keg is allowing CO2 to mix into the beer stream at the Out post. This happens if the small O-ring under the long Out dip tube flange is missing or damaged - and even a nick will do it if it's in the right place. That little O-ring prevents CO2 in the head space from being injected into the beer stream at the Out post, and the classic failure symptom is exactly what is related above...

Cheers!
 
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jas0420

jas0420

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That makes sense, thank you.

So, in theory, had I just moved the keg into the kegerator several weeks ago (detached from CO2 and faucet) the high head pressure would have been absorbed again from the drop in temp and I could have moved the lines over to it without the fuss.
 

SonomaBrewer

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Same batch, same gas line, same draft parameters raises a few questions:

1. Was it fully fermented when you put it in the keg? If not, higher temperature probably roused the yeast to produce more CO2.

2. I assume both kegs were initially carbonated cold in the kegerator -- when you stored it at 72 degrees, physics says several things happened:

a. Volume of beer in the keg went up (liquid expands as it heats)

b. Pressure in the keg went up (pressure and temperature are directly proportional)

c. CO2 equilibrium changed (as per @Jtvann), probably the most important -- the amount of CO2 that can be dissolved in liquid decreases as temperature rises (think about that bottle of soda that burst in the hot car).
 
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jas0420

jas0420

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Alternative explanation: the second keg is allowing CO2 to mix into the beer stream at the Out post. This happens if the small O-ring under the long Out dip tube flange is missing or damaged - and even a nick will do it if it's in the right place. That little O-ring prevents CO2 in the head space from being injected into the beer stream at the Out post, and the classic failure symptom is exactly what is related above...

Cheers!
Also interesting…. I could swap out the post fairly easily to test that. Thank you as well!
 

day_trippr

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Well, not the post - the O-ring is under the long dip tube flange.
So you'd have to swap dip tubes after removing Out posts...

Cheers!
 
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jas0420

jas0420

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Same batch, same gas line, same draft parameters raises a few questions:

1. Was it fully fermented when you put it in the keg? If not, higher temperature probably roused the yeast to produce more CO2.

2. I assume both kegs were initially carbonated cold in the kegerator -- when you stored it at 72 degrees, physics says several things happened:

a. Volume of beer in the keg went up (liquid expands as it heats)

b. Pressure in the keg went up (pressure and temperature are directly proportional)

c. CO2 equilibrium changed (as per @Jtvann), probably the most important -- the amount of CO2 that can be dissolved in liquid decreases as temperature rises (think about that bottle of soda that burst in the hot car).
I am pretty lazy about moving out of the fermenter. I watch it with a tilt hydrometer and, at best, it will be in there a couple of weeks after in flat lines.

Yes, at the time, I had enough space in the kegerator to carbonate cold. They stayed in there a few months before more real estate had to be made and the untapped came out.

thank you for the reply!
 
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jas0420

jas0420

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Well, not the post - the O-ring is under the long dip tube flange.
So you'd have to swap dip tubes after removing Out posts...

Cheers!
Crud…. Yes it is! (I was staring at a pile of posts on the table when I wrote that and didn't think that one all the way through.) I will sanitize another dip tube/o-ring and try a quick swap.
 
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jas0420

jas0420

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@day_trippr I wanted you to be the winner... I swapped out the dip tube and o-ring with a sanitized surrogate and, unfortunately, still wound up with the same results. Definitely making a mental note of that though. I'd never considered that before and it made a lot of sense!

Looks like this time it is a sin that only time will heal. Gotta admit that I still don't fullllllly grasp the science behind it. I get the warmer temp causing CO2 to come out of suspension and build up pressure in the headspace. I get that it wouldn't be magically reabsorbed with one one night of cool-down. So that leaves me with cold, slight-to-moderately under-carbonated beer.

I for-sure completely bled off the entire head pressure Friday night (and again when I pulled the dip tube just now), and reattached 10psi. I can't quite wrap my head around why I'm not just getting under-carbonated 36 degree beer pushed out. Who can dumb down the science for me? (I ask out of genuine curiosity, not doubt!)
 

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It's a good idea to check a kegs pressure before hooking it up. Would warn you if further ferment had occurred to increase psi and therefore vols.

A keg at 20 celsius and 24.51 psi has 2.3 vols of CO2 in it, cooling that keg to say 5 celsius you would see the pressure drop to 10.59 psi but the same amount of gas is in the keg just more in the liquid. But as mentioned above that equilibrium does take a bit of time. However the beer is not overcarbed due to the higher pressure in the headspace as you haven't got that extra CO2 back into the beer yet most likely had more vols in the beer anyway from before cooling started. Much like leaving a keg too long whilst force carbing.

Unless of course you find a hole in oring etc.

EDIT i was typing this whilst you posted your plea. Does it help?

your extra info re cold and flat now fits with the above explanation as well.
 
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jas0420

jas0420

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It's a good idea to check a kegs pressure before hooking it up. Would warn you if further ferment had occurred to increase psi and therefore vols.
Good tip...

A keg at 20 celsius and 24.51 psi has 2.3 vols of CO2 in it, cooling that keg to say 5 celsius you would see the pressure drop to 10.59 psi but the same amount of gas is in the keg just more in the liquid. But as mentioned above that equilibrium does take a bit of time. However the beer is not overcarbed due to the higher pressure in the headspace as you haven't got that extra CO2 back into the beer yet most likely had more vols in the beer anyway from before cooling started. Much like leaving a keg too long whilst force carbing.

Unless of course you find a hole in oring etc.

EDIT i was typing this whilst you posted your plea. Does it help?

your extra info re cold and flat now fits with the above explanation as well.

So am I right to think in my post above that if the beer truly was under carbonated (which I've been assuming up to this point, but am starting to question) and the head pressure was purged back to 10psi that the symptoms I'd see would be cold, semi-flat beer coming out of the faucet with minor to no foam (line length and o-ring issues aside)? Meaning foam would only come if the beer was actually over carbonated? It would have been really hard for me to mess up the initial carbonation (at the time, the kegs are all fed off of one regulator) so that really only leaves fermentation spinning back up... Which is interesting.

Thinking out loud here because my mind has drifted to the 30 gallons I'm needing to keg next weekend and don't have kegerator space. I had carb'd the last batch at room temp. If I recall, I played it safe and slightly undercarbonated it (at least according to the carbonation chart I was using). Those turned out well. In hindsight, it seems like I need to just do that exclusively going forward........
 

DuncB

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keep an eye on the keg pressures and then let some out if they are overpressure. I noted that a ferment that appeared finished in a fermentasaurus with some yeast still in the collection bottle the pressure kept going up and up and that a ring of bubbles was present on the beer surface. I had to vent it back to normal psi before using a party tap.

I think your beer was overcarbonated due to a very slow ongoing ferment, you plugged it in and then chilled it but still had too much push ( the unabsorbed CO2 ) from the higher ( relative ) pressure above the beer. I have just started to cold crash a beer that has been fermenting and was at 21 psi this morning and 17.3 celsius. It will probably be at 5 celsius by tomorrow am ( 24 hours ) and I'll see what pressure reading I get.

Am I right with your process that you put the keg in the fridge on 10psi, following day got foam, purged the keg flat in the headspace but then put it back on gas at 10 psi. If the liquid gas pressure was higher than 10 psi ( seems likely if headspace pressure and hence vols was up before starting this ) then more gas comes out of liquid to get balance of pressure. Next pour again foam and you revent again, think what happens when you open a bottle of lemonade suddenly bubbles rise up and disappear. Seal bottle up then it gets firm again and reopen similar but less bubble release until eventually you have very little CO2 left and flat lemonade. Putting pressure back on the lemonade does not cause equilibrium (especially as lemonade is ofter 3 or more vols ). Also why squeezing the lemonade bottle to get rid of headspace doesn't work because it refills with gas and actually accelerates the lemonade going flat. But try and convince my Dad of that and you are a better man than me.

I find this a useful tool for carbonation values.

But I wouldn't fret about the past issue it will come right in time if kept cool at 10 psi.
 
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jas0420

jas0420

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Am I right with your process that you put the keg in the fridge on 10psi, following day got foam, purged the keg flat in the headspace but then put it back on gas at 10 psi.
Correct.

I find this a useful tool for carbonation values.

But I wouldn't fret about the past issue it will come right in time if kept cool at 10 psi.
Thanks for the calculator link! That gets several degrees closer to room temp than my carbonation chart does, so that will take some of the guessing out of this upcoming (and future) brews I'll need to carb outside of the kegerator.
 

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@jas0420
So just an update on the beer that started to cold crash yesterday.
It was at 21 psi and 17.3 celsius 24 hours ago.

I've cold crashed it in the fridge/ freezer and 24 hours later it is at 1.25 celsius and the same gauge reads 18psi.
So only absorbed 3 psi in 24 hours. I plan to keep this cold crashed until the weekend then do a cold closed transfer to a keg and leave it at 6 celsius in a spare corner of the keg fridge.

I'll take daily readings until I have it in the keg and then it will go on my standard 14 psi ( I have non return valves which steal some psi ).

Interesting learning for me I will update tomorrow.
 
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jas0420

jas0420

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@DuncB I'm jealous. I've still got plastic fermenters and haven't been able to venture into the world of options that tanks which can old pressure would offer. Some day.... Some day.
 

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This has been an interesting read, and maybe your problem lies within the above. I just wanted to mention 2 other potential hardware issues just because they didn't come up in the discussion above:

1) There are o-rings inside you disconnect attached to your liquid line. Generally, if you had some sort of sealing failure in the disconnect, you'd likely also see beer weeping/leaking out of the disconnect, too. But an easy test to rule this out would be to just swap the line over from another keg to see if that changes anything. Of course some will say "But it was working fine on the last keg...", but if something's going to fail, it has to fail sometime. If the paradigm of "wasn't broken on last beer" was always true, you would have a never-ending chain of "last beers" and hence the equipment would never have a problem...

2) There's an o-ring on the outside of the post on your keg. Same would apply as above that generally speaking a defect here would cause a liquid leak out maybe as easily as a path for air to get sucked in while beer is flowing by. But these are cheap and easy to swap out just to rule it out.
 
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jas0420

jas0420

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This has been an interesting read, and maybe your problem lies within the above. I just wanted to mention 2 other potential hardware issues just because they didn't come up in the discussion above:

1) There are o-rings inside you disconnect attached to your liquid line. Generally, if you had some sort of sealing failure in the disconnect, you'd likely also see beer weeping/leaking out of the disconnect, too. But an easy test to rule this out would be to just swap the line over from another keg to see if that changes anything. Of course some will say "But it was working fine on the last keg...", but if something's going to fail, it has to fail sometime. If the paradigm of "wasn't broken on last beer" was always true, you would have a never-ending chain of "last beers" and hence the equipment would never have a problem...

2) There's an o-ring on the outside of the post on your keg. Same would apply as above that generally speaking a defect here would cause a liquid leak out maybe as easily as a path for air to get sucked in while beer is flowing by. But these are cheap and easy to swap out just to rule it out.
Valid points, thank you for adding to the conversation!

I tried swapping to the next faucet/line over (known "good") this morning and got the same result.

Definitely not getting any liquid leakage, but went ahead and swapped out the post o-ring after that and no change.

After the comments above, I've been going on the assumption that the beer is over-carbed and have been bleeding off pressure a few times a day with it still hooked to 10 psi. I went ahead and disconnected the gas line this morning, bled it off and I'll see later today if there's anything else to bleed off.

At this point, wondering if having it cold is going to prevent equilibrium to 10psi (if it truly is over-carbed). Trying to think if I have enough parts laying around to somehow hook up a pressure gauge directly to the keg to see what it's actually at (because I'm definitely guessing at this point). If I can't do that, I may give it a few shakes and bleeds, assume I got it down under 10psi, and let it sit peacefully undisturbed at 10psi for several days as if it had just come out of the fermenter.
 

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Really tricky without a pressure gauge.
No spunding valve I assume with a gauge on?

If so the only gauge you have is the one on your regulator and you'd need to disconnect any other kegs from this when you test.
But if you bleed to nothing and wait dissolved gas will come out of solution quite quickly ( as per opened lemonade bottle ) , leave it not on the CO2 and check after a couple of hours, if it's over 10 psi then you may well have your answer. If it's at 10 psi or less then you either did a final bleed to right level or have a problem elsewhere.

Have you cleaned the lines and tap thoroughly if not that can cause foaming issues and should be done anyway.
 
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jas0420

jas0420

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Clean the lines... Huh?? Just kidding. That one had only a few gallons pushed through it up until that point, but I did swap it with a brand new line last weekend when I was trying different lengths. Old kegerator konked out earlier this year and I took the opportunity to re-plumb everything w/ EVABarrier, so just about everything is all shiny and new.

I haven't had a chance to go through my spare hardware yet, but I'd be surprised if I can't rig up a way to get a pressure gauge onto a gas disconnect. Pretty sure I have at least one of every part ever made.... If I can't, this has made it clear that I have a gap in my toolbox that needs to be filled.
 

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You've got the bases covered then will stand by.
I have a couple of digital pressure gauges and they go thru batteries fast. I prefer the analogue gauges over the electronic, even though they don't look as flash.
 
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jas0420

jas0420

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That was harder than it should have been, but I managed to MacGyver together a gauge. Only read ~5psi after sitting disconnected since bleeding off this morning.

Didn’t know if that was because it was cold and not wanting to release gas easily so I went ahead and went through a few shake/bleed cycles for good measure.

Dropped it back into the kegerator, hooked it back up to 10psi and going to just let it be for a while. Have a couple more kegs that have been sitting out at room temp like that one. Threw those in and am going to watch what the pressure does.
 

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Did you pressure check those other kegs before they went in? If you have a clue about the beer temp you'll know whether you are going to be okay.

If the foamy keg is now around 5 psi and cold it should get to the right level in time.
 

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Just wondering, have you checked the gaskets in your faucets? Long shot here but I was having a serious problem with foam and the problem was that the gasket between the faucet housing and spout was not set properly. Also if you have a picnic tap you may want to try that out and see if you get the same issues. Good luck!
 

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Just had a serious foam issue. Turned out I had a messy transfer and a lot of hop crap got in the keg. Had to pull the out poppet and a ton of crap was in it. Better now after clearing the poppet and dip tube and making a complete mess.
 

TkmLinus

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Just had a serious foam issue. Turned out I had a messy transfer and a lot of hop crap got in the keg. Had to pull the out poppet and a ton of crap was in it. Better now after clearing the poppet and dip tube and making a complete mess.
I place a 5 gallon paint straining bag in my kegs when I transfer. Never have a problem with hop material.
 
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jas0420

jas0420

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Sorry, been away from the board for a while....

Did you pressure check those other kegs before they went in? If you have a clue about the beer temp you'll know whether you are going to be okay.

If the foamy keg is now around 5 psi and cold it should get to the right level in time.
By chance I did! 34psi going in, 17psi the next day, and 10psi the day after, then I hooked them up to 10psi. SOOOOO... At least on the first day I tried pouring, I was most likely around 17psi. Can't explain the second and third and fourth days still.... I have managed to just leave it alone since getting it down to 5psi. Going to hold off a bit more (mostly b/c I don't want to be mad).


Just wondering, have you checked the gaskets in your faucets? Long shot here but I was having a serious problem with foam and the problem was that the gasket between the faucet housing and spout was not set properly. Also if you have a picnic tap you may want to try that out and see if you get the same issues. Good luck!
Thx for the suggestion! When I was going through everything above though, I did move another known-good faucet/line/quick disconnect from one keg to the trouble maker and got the same results unfortunately.


Just had a serious foam issue. Turned out I had a messy transfer and a lot of hop crap got in the keg. Had to pull the out poppet and a ton of crap was in it. Better now after clearing the poppet and dip tube and making a complete mess.
Interesting... At this point, the post & poppet are the only thing I haven't swapped out. I should have done that while I had it off and changed the dip-tube & o-ring. When I muster the courage to try again, I'll take a look at that if the foam is still here. That, or throw the keg out the window...


I place a 5 gallon paint straining bag in my kegs when I transfer. Never have a problem with hop material.
Knocking on wood here, but I've not really had much of an issue with extra material winding up in the keg. I push everything through one of brewershardware.com's .4mm strainers before it goes into the fermenter. I've definitely clogged THAT up many times. I need to find a better containment system for the boil kettle. I have a big 6" x 14" hop spider, but no matter how hard I try it always boils over and I just as well had dumped the hops straight in. The hop spider needs a lid. Was actually just looking at that today. I seem some smaller ones with screw on lids. May try a few of those if I can't find a big one.

I love bottling.....
As maddening as this has been, I'd never go back to bottling! haha!
 
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jas0420

jas0420

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Success! Got a normal pour today... Last thing I did was the shake/bleed/repeat to get it down to about 5psi and it's been sitting on a 10psi connection for 6 or 7 days. Thanks again everyone for the ideas and insight. Learned a few things and now own a spunding valve & regulator to keep an eye on this sort of thing going forward.
 
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