Author Topic: Question About Beer CO2 Absorption  (Read 1151 times)

Offline ultravista

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Question About Beer CO2 Absorption
« on: April 18, 2015, 07:19:19 PM »
I have a keg that was connected @ 15 PSI for 4 days at 75-80F while dry hopping. When connected w/gas, I found no leaks. There is a smidgen less than 5 gallons in the keg.

After a four days, I removed the gas and let it sit for another 2-3 days.

Today, when moving it into the refrigerator, I found it to be depressurized. The pressure release gave nothing.

I've got it back under gas, the lid and out post are soaped. No bubbles ...

Is it possible the beer absorbed the gas? Does this sound plausible for the lack of gas in the headspace (minor headspace)?

Offline HoosierBrew

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Re: Question About Beer CO2 Absorption
« Reply #1 on: April 18, 2015, 07:28:30 PM »
Is it possible the beer absorbed the gas? Does this sound plausible for the lack of gas in the headspace (minor headspace)?

Yep. The beer needs to stay connected for around 2 weeks to carbonate fully to your pressure setting. And then afterward it helps to keep the pressure on the keg, to keep the lid seated.
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Offline ultravista

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Re: Question About Beer CO2 Absorption
« Reply #2 on: April 18, 2015, 07:35:52 PM »
The lack of headspace gas is not necessarily indicative of a leak then?

Offline HoosierBrew

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Re: Question About Beer CO2 Absorption
« Reply #3 on: April 18, 2015, 07:40:21 PM »
It's possible too, but it seemed most likely that the CO2 just got absorbed since it was only connected for 4 days. Best way to test - reconnect to CO2 and spray the keg lid, PRV, and QDs with starsan and look for big bubbles forming in the starsan. If no leaks are noticeable, your beer absorbed the CO2. I'd bet on it.
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Offline ultravista

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Re: Question About Beer CO2 Absorption
« Reply #4 on: April 18, 2015, 07:50:14 PM »
I see no bubbles; all looks good.

Having lost tanks before, I was uncertain about the absorption. It's cooling now and under gas again.

Offline Black Sands Brewery & Supply

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Re: Question About Beer CO2 Absorption
« Reply #5 on: April 19, 2015, 12:10:07 PM »
the co2 will absorb faster when the beer is cold. the colder the beer and the higher the pressure the faster it will carb up. here is a link to a chart: http://www.kegerators.com/articles/carbonation-table-pressure-chart.php

doubt the co2 absorbed in to the beer when it was above 70 F.
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Offline ultravista

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Re: Question About Beer CO2 Absorption
« Reply #6 on: April 19, 2015, 01:27:45 PM »
doubt the co2 absorbed in to the beer when it was above 70 F.

Do you then say it was a leak?

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Re: Question About Beer CO2 Absorption
« Reply #7 on: April 19, 2015, 02:20:55 PM »
possibly... that is just too high a temp for it to absorb.
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Offline Jimmy K

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Re: Question About Beer CO2 Absorption
« Reply #8 on: April 19, 2015, 02:33:47 PM »
It will absorb at 70, just not as much. But 4 days @ 15 isn't nearly enough to get the beer to saturation. Also if it cooled at all then you also have thermal shrinking of the beer, which will increase headspace slightly.
« Last Edit: April 20, 2015, 07:02:00 AM by Jimmy K »
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Offline YooperBrew

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Re: Question About Beer CO2 Absorption
« Reply #9 on: April 19, 2015, 05:14:33 PM »
possibly... that is just too high a temp for it to absorb.

If there is pressure in the headspace, the co2 will diffuse into the beer as it seeks equilibrium.  That's the Laws of Physics, particularly the Ideal Gas Law. 

Beer can easily be carbonated at 70 degrees.  It requires more psi (but not more gas) to do so, but even at 15 psi, the beer will absorb the gas in the headspace until equilibrium is reached. 

Offline alestateyall

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Re: Question About Beer CO2 Absorption
« Reply #10 on: April 19, 2015, 06:21:47 PM »

possibly... that is just too high a temp for it to absorb.

If there is pressure in the headspace, the co2 will diffuse into the beer as it seeks equilibrium.  That's the Laws of Physics, particularly the Ideal Gas Law. 

Beer can easily be carbonated at 70 degrees.  It requires more psi (but not more gas) to do so, but even at 15 psi, the beer will absorb the gas in the headspace until equilibrium is reached.
That's Henry's Law, actually.

Offline yso191

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Re: Question About Beer CO2 Absorption
« Reply #11 on: April 20, 2015, 07:50:56 AM »
I want a law named after me. 
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Offline euge

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Re: Question About Beer CO2 Absorption
« Reply #12 on: April 20, 2015, 08:00:51 AM »
I don't believe the beer can absorb enough co2 to disrupt the keg's main seal and cause it to lose pressure or depressurize.

More likely there is a minor leak somewhere or unrealized operator error.
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Offline morticaixavier

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Re: Question About Beer CO2 Absorption
« Reply #13 on: April 20, 2015, 08:19:51 AM »
I have a keg with a bad popette (yes I should replace it and I even have the new piece, just haven't done it yet) when I remove the gas QD it starts losing gas through the post. I can jimmy with the popette and it stops but I don't trust that keg for long term storage. You could well have a popette with a slow leak. it wouldn't show up while the gas was connected.
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Offline Joe Sr.

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Re: Question About Beer CO2 Absorption
« Reply #14 on: April 20, 2015, 08:37:59 AM »
I have a keg with a bad popette (yes I should replace it and I even have the new piece, just haven't done it yet) when I remove the gas QD it starts losing gas through the post. I can jimmy with the popette and it stops but I don't trust that keg for long term storage. You could well have a popette with a slow leak. it wouldn't show up while the gas was connected.

I've fixed this on a couple kegs recently, and it can be a sneaky problem.  On one of the fixes, the o-ring on the universal poppet was torn, so I replaced the problem with the same problem.  Drove me a little crazy.

I also believe that if the keg has relatively low pressure already and then you chill it, you can lose the seal on your lid.  That's my theory, anyway.  I've moved kegs to the fridge and had them seem like they have no head pressure once they chill.  Well carbed, but no pressure.
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