nothing but foam

Tapped a robust porter tonight....beer was quick carbed at 30 psi for about 5 minutes of shaking then just stored cold with no gas attached for a week or so.. I am getting nothing but foam.. the thing is if I purge the keg turn the gas back on and run off a pint, it is perfect.......until I let it set for 5 minutes, then it is all foam again...if I run out what is in the beer line it is perfect again.. I can see the beer line filling up with bubbles if I lift the lid on teh kegerator....If the beer is actually over carbed why is ONLY the beer in the line foamy? I have 12 foor lines set at 12 psi give or take... every other keg is fine.

what is your pouring temperature?
what type of keg (corny or sankey)?
how much headspace was in the keg when you applied 30 PSI of pressure?
what temperature did you carbonate at?
what type of equipment have you tapped with? (length and type/size of tubing, type of faucet, etc.)

I work professionally in draught beer dispense equipment installations and servicing, and have for the past 8 years.
In my experience dealing with commercially packaged beer, nearly all foaming problems are either due to either temperature or pressure. Home-brewing however does add the bogeyman of over-carbonation. If you can answer all of these questions I can probably help you out.

BTW. what is your target carbonation level (in volumes of CO2)? I assume for a robust porter that you are looking for 1.8 to 2.3

I see that you just replied to my thread. Are we the only 2 on the forum right now?

I had similar problems and think it came from over carbonation. I just release the pressure on the keg completely and shake then repeat at least three times. One thing that also worked for me was to disconnect the gas and shake the keg while dispensing. Once there is no longer any discharge of foam or liquid, I let it set overnight and start with 12 psi and things are usually alright.

I've never done the shake at 30 psi method. Read about it, sounds like more people have problems with overcarbonation and Carbonic acid flavor than success. I haven't had the patience for setting at serving pressure and forgetting for a few weeks either. I've done high pressure for a day or two, lower a bit and then set at serving pressure. Varied success with that.

There was a thread on here where a guy suggested a combination of shaking at serving pressure. It made sense. Can't overcarbonate if your forced CO2 pressure is serving pressure and you can get CO2 into solution quickly with the shake method.

I haven't tried it yet for two reasons. 1. Don't have a brew ready to try this method. 2. Worried about unsettling all the yeast and trub I used a cold crash to get out of the beer.


I have a few beers ready to keg and force carb in the next few weeks. The beer I find least favorable I'm going to try setting at serving pressure and shaking and the other two set and forget method. .. If I have the patience

schroeder said:

what is your pouring temperature?
what type of keg (corny or sankey)?
how much headspace was in the keg when you applied 30 PSI of pressure?
what temperature did you carbonate at?
what type of equipment have you tapped with? (length and type/size of tubing, type of faucet, etc.)

I work professionally in draught beer dispense equipment installations and servicing, and have for the past 8 years.
In my experience dealing with commercially packaged beer, nearly all foaming problems are either due to either temperature or pressure. Home-brewing however does add the bogeyman of over-carbonation. If you can answer all of these questions I can probably help you out.

BTW. what is your target carbonation level (in volumes of CO2)? I assume for a robust porter that you are looking for 1.8 to 2.3

Click to expand...

CORNEY
KEG WAS FULL.. JUST BELOW THE GAS IN TUBE ( sorry caps)
Not sure of exact temp.. just cold crashed and kegged right out of a fridge.
12 PSI with 10 foot of 1/4 inch tubing . perlick taps.....As I said, every other keg is fine ( I have a 6 tap kegerator) I have just over carbed it. The thing I can't figure is why once I get past the beer in the line, it is fine.

It's overcarbed. Just as an example, say it is carbed to 15 psi and served at 12 psi. When it sits there for any length of time, the pressure equalizes and your keg really is at 15 psi even if the CO2 tank is set at 12. When you draw off the first pint, it will be like serving at 15 psi and you'll get a glass of foam. If you purge the tank, you drop that pressure down to a proper serving pressure and the beer flows OK. You let it sit of a half an hour and you build up more pressure and then you are foaming again. Not as bad as if you let it sit overnight, but still foaming. As you remove some liquid, the pressure drops in the keg from serving, and the foam subsides.

The fix is just to disconnect the tank, purge, wait, purge, wait.... until you get the keg carbonation stabilized at your serving pressure. If your foam is drying quickly on the second pull, you probably aren't that far off and you should hit it pretty quickly.

OK did the thing where you hook up the gas to the beer out line and purge.. it worked but I lost a lot of beer to foaming out the relief valve.

OHIOSTEVE said:

CORNEY
The thing I can't figure is why once I get past the beer in the line, it is fine.

Click to expand...

If you have an equilibrium of 15psi in the headspace balanced with the gas dissolved in the liquid. Then 15psi pressure is required to keep the gas in the beer.

when you crack the cap on a plastic pop bottle you can see the bubbles immediately nucleate and come rushing to the surface because there is no longer sufficient pressure to hold the gas in the pop. If you re tighten the cap the bubbles will continue to break out until the pressure in the headspace establishes a new equilibrium.

You do not have enough counterpressure at 12psi to keep the gas from breaking out. Only the gas that breaks out in the line causes foam. the gas breaking out into the headspace of your keg is not affecting the pour. When it sits, the bubbles accumulate in the line. The bubbles then in turn cause turbulence when you pour and cause more breakout and foam.

As far as your dispensing system is concerned... I would advise against using 1/4" tubing. The industry standard is 3/16" ID vinyl tubing ('choke line', or "restriction line') which provides 3lb. of flow restriction per foot. You can dispense a higher carbonation beer by adding more restriction and increasing your dispense pressure to keep the gas from breaking out in the line.

Additionally, if you are slightly over carbonated, the smaller diameter tubing will purge more quickly, and you may still get a reasonable pour, because there will be significantly less volume of foam (ie: 10' of 1/4" tubing has a volume of 5.9 cubic inches, whereas 4' of 3/16" tubing has a volume of 1.3 cubic inches)

There are other restriction values for the hardware in the system (poppet valve, cornelius QD, faucet, # of feet of vertical rise etc. but the quick test is with the appropriate counter-pressure applied to your keg (sufficient to prevent breakout) your product should pour at 2oz. per second (7 seconds for a 16oz. glass yielding 14 oz of beer and 2oz. of head for example).

Carbonation values are closely linked to temperature as well. 2.4vol of CO2 at 38F only requires about 12psi (I could be off slightly I would need to consult a chart to verify precisely) but at 64F the same carbonation value requires about 26psi (previously mentioned caveat)

charts with the temperature to pressure relationship used to be available at mcdantim.com you may have better luck finding them than I've just had, but they do make a nifty FREE tool called the "McDantim Slide Rule" that you can also use for selecting your carbonation pressure for different temperatures (I use this thing all the time at work, and have since started using it for calculating my homebrew carbonation values) Send an e-mail to [email protected] to request one.

I mention all of this in case you want to make a more efervescent beer in the future, or if you wish to serve a beer at a warmer temperature, but as previously suggested for your porter... shake the piss out of it, rest briefly then bleed off the pressure... do it 3 times, put 12psi back on after it settles and see how it pours. Repeat as necessary.

After the trouble, I'd suggest not doing the shake method. I can take a beer from fermenter at 70, to chilled, carbed and ready to drink at 12psi in 5-6 days without touching it.