Help! My keg pours nothing but foam

[andycr]

I have a keg with 3' or so of line and a picnic tap. It's been carbing for about 4 days now, with a few hours at 27 PSI followed by the remainder at serving PSI of around 11.

The beer comes out as nothing but foam. As a result, it's still almost flat - all the CO2 simply comes out of solution during the pour, and you get an entire glassful of foam you have to wait to drink. There's no foam in the lines - it runs clear there.

I'm completely new to kegging - what am I doing wrong?

 

[blaster_54738]

first off a few hours at 27 psi won't do much for carbonation, a couple days at that pressure then release the pressure to serving would help more. secondly your beer line is probably too short. it's recommended to use at least 5 feet but you'll see a lot of people running 10 feet of beer line (me included)

 

[Hopper77]

Picnic taps suck. When I used mine I had to drop the serving pressure to like 3psi.

 

[jonmohno]

Im new too to kegging. Heres my story so far. I racked cold hit a 2 gallon amount in a 3 gal keg with 16 psi.I purged after 30 hrs- dropped it to ten got foam,like I was expecting but also a semi carbonaed beer otherwise.Poured again got foam then semi carbed beer flowing slower yet somewhat flattish also. 3 days later sitting at 10 I tonight decide to pour, I get foam initially but full throttle it seems to mellow and slow but still got about 1/2 glass of foam yet it was still carbed.I think if I pour another it may be somewhat flattish. I did hear the keg start to fill again after my last 1/2 glass(1/2 head/ 1/2 beer) pour which was yet another surprise for me.Whatever that means. I hate to say it too, but it tastes or smells a bit gassy and Ive had a headache more it seems since ive been trying samples. I had a pretty terrible headache after first kegging a few days ago also yet I did have a few more than normal but I never really get headaches.

I dont want to overcarb it but I have no clue if im going to undercarb it by turning it down to 5 for serving pressure. I also know this needs a a week or two to conditon/clear but I dont want to keep wasting samples trying to decide if its really carbonated yet or not especially when I know it needs some time on it.

Well, I just poured a bit more and it is flattish so I guess Im ok for another week to check maybe. I guess Im really just afraid of leaving it at 10 for 2 more weeks. From what I read it appears to leave it at 10 for 3 weeks.Not shure if that means after that purge it turn it down to whatever serving pressure then drink or just leave it at 10?

 

[andycr]

I dont want to overcarb it but I have no clue if im going to undercarb it by turning it down to 5 for serving pressure. I also know this needs a a week or two to conditon/clear but I dont want to keep wasting samples trying to decide if its really carbonated yet or not especially when I know it needs some time on it.

Well, I just poured a bit more and it is flattish so I guess Im ok for another week to check maybe. I guess Im really just afraid of leaving it at 10 for 2 more weeks. From what I read it appears to leave it at 10 for 3 weeks.Not shure if that means after that purge it turn it down to whatever serving pressure then drink or just leave it at 10?

Doubt the headache came from CO2, probably a coincidence. Sounds like a similar situation to me. No idea how to fix it, you'll probably get better answers if you start a thread on it.

Thanks for the replies. My thought on only leaving it at 27 for a few hours was I'm kegging 2.5 gallon batches in 5 gallon kegs, so the headspace to beer ratio is much higher. I wasn't sure how that would impact CO2 absorption, so I decided to play it safe.

I broke the plastic on the spout of my picnic tap jamming a racking cane in too hard to test bottling (and painted my walls, floor, and self with pale ale), so I have to go to the LHBS tomorrow anyway. I'll grab 7-10 feet of line while I'm at it.

 

[raouliii]

... My thought on only leaving it at 27 for a few hours was I'm kegging 2.5 gallon batches in 5 gallon kegs, so the headspace to beer ratio is much higher. I wasn't sure how that would impact CO2 absorption, so I decided to play it safe......

The amount of headspace shouldn't impact the speed at which the beer carbs up. The controlling factor is the pressure. With that much headspace, I would be more concerned about the amount of air that remains in the headspace. It would take quite a few purges to dilute half a corny of air down to minimal levels of O2.

 

[andycr]

The amount of headspace shouldn't impact the speed at which the beer carbs up. The controlling factor is the pressure. With that much headspace, I would be more concerned about the amount of air that remains in the headspace. It would take quite a few purges to dilute half a corny of air down to minimal levels of O2.

How many do you think? It's probably been purged 5 times with my bottling and pressure experiments, but for the future it would be good to know how little CO2 I can get away with wasting.

Went to the LHBS today and got 10' of 3/16 line and a new picnic tap. Put it all together, still all foam. So I tried to open the picnic tap less, to pour more slowly. Even more foam. Then I opened the tap all the way, and it pours foam-free with a perfect amount of head. Problem solved.

 

[raouliii]

How many do you think? It's probably been purged 5 times with my bottling and pressure experiments, but for the future it would be good to know how little CO2 I can get away with wasting........

Maybe someone with more knowledge about the physics of gas will chime in on this question. O2 makes up about 21% of air. By introducing 100% CO2 to the headspace at a particular pressure, there should be a mathematical way to determine the remaining % of O2 for each pressure release, "purge", cycle. One thing I am fairly sure of is that during this type of "purging", there is no "layering" of CO2 in the headspace that some posters claim. Pushing CO2 into the headspace creates more than adequate turbulence to have complete mixing of the gases in the headspace, so this is really an excercise in dilution, not "purging". I'm not sure what the acceptable residual O2% level would be to reduce oxidation to an acceptable rate.

...Then I opened the tap all the way, and it pours foam-free with a perfect amount of head. Problem solved.

I believe most, if not all, taps are designed to be used fully open. A partially open tap will create turbulence in the flow that will generate foam. There are a few taps that have adjustable metering devices built into them.

 

[StoneHands]

I believe most, if not all, taps are designed to be used fully open. A partially open tap will create turbulence in the flow that will generate foam. There are a few taps that have adjustable metering devices built into them.

This good advice. Think of the tap as a switch instead of a valve - on or off.

 

[Tarks]

Maybe someone with more knowledge about the physics of gas will chime in on this question. O2 makes up about 21% of air. By introducing 100% CO2 to the headspace at a particular pressure, there should be a mathematical way to determine the remaining % of O2 for each pressure release, "purge", cycle. One thing I am fairly sure of is that during this type of "purging", there is no "layering" of CO2 in the headspace that some posters claim. Pushing CO2 into the headspace creates more than adequate turbulence to have complete mixing of the gases in the headspace, so this is really an excercise in dilution, not "purging". I'm not sure what the acceptable residual O2% level would be to reduce oxidation to an acceptable rate.

I believe most, if not all, taps are designed to be used fully open. A partially open tap will create turbulence in the flow that will generate foam. There are a few taps that have adjustable metering devices built into them.

I'm just thinking out loud and I could be way off here but we all know that CO2 is heavier than Oxygen. Therefore, all you need is a small blanket of CO2 on the beer. You don't actually need to displace 100% of the oxygen from the keg do you? You could have 10% CO2 and 90% oxygen in the head space and you should be fine. So long as the 10% CO2 is enough to blanket the entire surface of the beer. Am I wrong here?

 

[day_trippr]

Maybe someone with more knowledge about the physics of gas will chime in on this question. O2 makes up about 21% of air. By introducing 100% CO2 to the headspace at a particular pressure, there should be a mathematical way to determine the remaining % of O2 for each pressure release, "purge", cycle. One thing I am fairly sure of is that during this type of "purging", there is no "layering" of CO2 in the headspace that some posters claim. Pushing CO2 into the headspace creates more than adequate turbulence to have complete mixing of the gases in the headspace, so this is really an excercise in dilution, not "purging".

Ok, so based on the above the math is simple: it's a progression of halves.
So the first purge drops the O2 content to 11.5%, the second to 5.75%, the third to just under 3%, the fourth to just over 1.4%, and the fifth to ~.7%. Easy as pie - as long as the "complete mixing" is true. Otherwise it all goes to hell

I'm not sure what the acceptable residual O2% level would be to reduce oxidation to an acceptable rate.

Nor do I. I do know The Bigs strive for insanely low packaged O2 content, and have come up with some fairly novel ways to achieve that end...

Cheers!

 

[raouliii]

I'm just thinking out loud and I could be way off here but we all know that CO2 is heavier than Oxygen. Therefore, all you need is a small blanket of CO2 on the beer. You don't actually need to displace 100% of the oxygen from the keg do you? You could have 10% CO2 and 90% oxygen in the head space and you should be fine. So long as the 10% CO2 is enough to blanket the entire surface of the beer. Am I wrong here?

IMO
I think you're off base. The turbulence created when CO2 is injected into the headspace will cause the CO2 and air to mix.

The whole "blanket of CO2" is more of a fermentation thing. Because the headspace in a carboy is a closed, still, environment, the CO2 that bubbles to the surface of the wort/beer will tend to remain there and slowly push any residual air out above it.

In a completely calm keg, the various gases would tend to separate but each draw on the tap would mix them back up again due to the co2 moving in to maintain the pressure. Compressor vibrations might even be enough to keep the gases mixed.

Ok, so based on the above the math is simple: it's a progression of halves.
So the first purge drops the O2 content to 11.5%, the second to 5.75%, the third to just under 3%, the fourth to just over 1.4%, and the fifth to ~.7%. Easy as pie - as long as the "complete mixing" is true. Otherwise it all goes to hell .....

I would expect it to be a function of the pressure achieved in between each purge cycle. If the keg were pressurized to 50psi, for example, I would expect that more CO2 would have entered the headspace than if it were pressurized to 10psi, thereby diluting the original headspace at a different %.