Foaming beer in keg strategy question

[Belgian Samurai]

Hi,

My kegged beer wasn't at the carb level I wanted, so I increased it too much and shook it, now I'm working on being the carb level back down. Haha yesterday, I set the CO2 tank down to 12psi and released all of the pressure from the keg, so there's only 12psi on it now. However, yesterday afternoon, it was still pouring foam.

That was the back story. Here's my question: since CO2 is heavier than O2, if I were to shut off the CO2 flow and open the PRV for an hour, would the off-gassing CO2 keep the oxygen out of my beer? I want to pour beer, not foam.

Thanks in advance!

 

[SanPancho]

in theory, yes. and given the small diamter of the PRV holes i'd say its probably gonna be ok.

but you might want to look into a thread that was just floating around about this very subject. essentially, you swap your gas to the beer post and blow a bunch of co2 through the bottom of the keg, letting it escape via the prv or the gas post. seems to work based on how folks responded.

 

[Belgian Samurai]

Esentially, you swap your gas to the beer post and blow a bunch of co2 through the bottom of the keg, letting it escape via the prv or the gas post. seems to work based on how folks responded.

That sounds like a good idea, but I don't think will work for me since I use a floating diptube. I'll keep it in mind though.

 

[Belgian Samurai]

I opened the PRV for an hour, but the tap still poured a glass of foam with a serving pressure of 12psi, so now I opened it up again and set a 4hr timer.

I'm contemplating the idea of opening the keg lid for an hour if this next 4hr ope PRV scenario doesn't work.

 

[balrog]

When you add a spoonfull of sugar to a cold glass of iced tea, does it dissolve instantly? No.
Neither does CO2 dissolve into or out of beer instantly. OK, if you throw in a handful of salt, hops, granulated yak dust, or any other nucleation points, CO2 will come of solution pretty quickly.

You should pull the PRV valve to release ALL pressure, then let it close, take the keg out of the keezer to warm for 24hr, which will cause CO2 out of solution, release the PRV valve to release all that, then put keg back in keezer without CO2 hook up, let it cool back down another day, then you'd be ok.

Or as @SanPancho mentioned, you could try the "Bubble CO2 through keg" method to force CO2 out of solution quickly. I have not tried this as I cannot imagine the mess it makes, the sediment it stirs up, etc.

 

[seilenos]

If you have a dual gauge regulator ....

• Turn your CO2 off at the tank.
• Vent via PRV.
• The low side gauge will now read zero.
• Check on the low side gauge every so often. At some point it will stop rising. This is the pressure at which your beer is carbed to.
• If it is more than 12 psi, repeat from "Vent via PRV". (You don't actually need to wait until it stops rising though ... if it is above 12 psi when you check, vent.)
• Once it stabilizes at or below 12 psi, open your CO2 tank and set to 12 psi.

 

[balrog]

If you have a dual gauge regulator ....

• Turn your CO2 off at the tank.
• Vent via PRV.
• The low side gauge will now read zero.
• Check on the low side gauge every so often. At some point it will stop rising. This is the pressure at which your beer is carbed to.
• If it is more than 12 psi, repeat from "Vent via PRV". You don't actually need to wait until it stops rising though ... if it is above 12 psi when you check, vent.
• Once it stabilized at or below 12 psi, open your CO2 tank and set to 12 psi.

This is a good method, and will take a few days. Maybe even a week.

 

[seilenos]

Alternatively, turn off CO2 and attach a spunding valve set to 12 psi.

It's a toss up if this would be faster because while it is a constant release of pressure the equilibrium is 12 psi whereas the vent method has bouts of 0 psi to out-gas faster against.

This certainly is the lazier way and ensures you don't drop below your intended carbonation.

 

[SanPancho]

Alternatively, turn off CO2 and attach a spunding valve set to 12 psi.

It's a toss up if this would be faster because while it is a constant release of pressure the equilibrium is 12 psi whereas the vent method has bouts of 0 psi to out-gas faster against.

This certainly is the lazier way and ensures you don't drop below your intended carbonation.

you can speed it up by bringing the keg out of the cooler or letting the temp rise. the only caveat being you have to do the math and figure out if your spunding valve can handle the pressure at room temp, which will be much higher than at ~40F.

 

[Bobby_M]

Hi,

My kegged beer wasn't at the carb level I wanted, so I increased it too much and shook it, now I'm working on being the carb level back down. Haha yesterday, I set the CO2 tank down to 12psi and released all of the pressure from the keg, so there's only 12psi on it now. However, yesterday afternoon, it was still pouring foam.

That was the back story. Here's my question: since CO2 is heavier than O2, if I were to shut off the CO2 flow and open the PRV for an hour, would the off-gassing CO2 keep the oxygen out of my beer? I want to pour beer, not foam.

Thanks in advance!

Just because CO2 has a heavier molecular weight than O2 doesn't mean they don't mix. If you leave the PRV open, air will absolutely enter.

When there is 20psi of CO2 dissolved in a beer and you vent the headspace down to zero, the co2 will seek equilibrium over time so the headspace will creep up to something like 19psi and that's also what the beer has. The exact new pressure is related to how full the keg is.

The options are to keep venting the headspace down to zero every hour until you hit the carb level you wanted or you can also put a spunding valve on the gas port set to the pressure you want the whole keg at. The latter will take longer but it doesn't require your intervention.

 

[wsmith1625]

Here is a solution (not mine) which I've shared with others in the past and it works.

https://www.homebrewtalk.com/threads/overcarbed-keg-heres-an-instant-solution.127655/

 

[Skeeter686]

I haven't tried this, myself, but I've heard that if you tap the side with a rubber mallet, you'll cause the CO2 it to come out of solution pretty quickly. Tap, vent, repeat a few times and you might be OK.

 

[doug293cz]

If you have a dual gauge regulator ....

• Turn your CO2 off at the tank.
• Vent via PRV.
• The low side gauge will now read zero.
• Check on the low side gauge every so often. At some point it will stop rising. This is the pressure at which your beer is carbed to.
• If it is more than 12 psi, repeat from "Vent via PRV". (You don't actually need to wait until it stops rising though ... if it is above 12 psi when you check, vent.)
• Once it stabilizes at or below 12 psi, open your CO2 tank and set to 12 psi.

This won't work if you have a check valve between your regulator and keg. Many regulators and distribution manifolds have buillt-in check valves. In this case you will not see pressure build back up on your low pressure gauge (unless your check valve leaks.)

If you have a free-standing pressure gauge (say on a spunding valve) you can put this on the gas post to watch the pressure rise.

Also, the first post in the thread is a real life example of why I tell people never to put more than chart pressure on a keg, and then agitate it to speed up carbonation.

Exception: If you know the level of carbonation already in the beer, and you have a scale sensitive to gram level weight changes in a full keg, you can use weight gain to determine when you have added enough CO2, and stop shaking.

Brew on

 

[balrog]

Also, the first post in the thread is a real life example of why I tell people never to put more than chart pressure on a keg, and then agitate it to speed up carbonation.

Because of that um that thing, it's um, you know, that oh yeah
Remembering to do, or unhook something.

 

[Belgian Samurai]

FOUND THE PROBLEM! woohoo!

Due to an inferior design of an old diptube O-ring, the pop-it was sucking in air. I replaced that with a new unit that is better designed and there is no longer a problem.

Thanks everyone for weighing in on the topic!

 

[seilenos]

This won't work if you have a check valve between your regulator and keg. Many regulators and distribution manifolds have buillt-in check valves. In this case you will not see pressure build back up on your low pressure gauge (unless your check valve leaks.)

I can only speak to my experiences but I only trust the check valves to stop "impulse" type liquid events from backing beer into the manifold/regulator. That is, sustained gas back pressure will eventually work its way through the system.

Maybe that's because I'm cheap...