Do you turn off your Co2? - Page 2 - Home Brew Forums

 Home Brew Forums > Do you turn off your Co2?

04-24-2007, 09:17 PM   #11
Chillbrook
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Jan 2007
Posts: 73

So say I fill my keg, hook it up to my system and set it to 12 psi. Once the beer is carbed (say after a week or so), if I leave my co2 ON will the beer continue to carb, thus becoming overcarbed? Or does it simply stay at 12 psi until I raise the pressure?

04-24-2007, 09:23 PM   #12
johnsma22

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Taunton, MA
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The amount of CO2 that can go into solution at 12 psi is dictated by the temperature of the beer. As long as the temperature does not change, and the pressure remains at 12 psi, the beer will only absorb what it can and no more. It is said to have reached a state of equilibrium. The pressure between the tank and the keg is now static and there is no flow. That is until you dispense some beer, then the CO2 will flow into the keg to filled the now increased headspace and equilibrium is again reached.
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04-24-2007, 10:01 PM   #13
Chillbrook
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Jan 2007
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Quote:
 Originally Posted by johnsma22 The amount of CO2 that can go into solution at 12 psi is dictated by the temperature of the beer. As long as the temperature does not change, and the pressure remains at 12 psi, the beer will only absorb what it can and no more. It is said to have reached a state of equilibrium. The pressure between the tank and the keg is now static and there is no flow. That is until you dispense some beer, then the CO2 will flow into the keg to filled the now increased headspace and equilibrium is again reached.
So if I do not dispense the beer will not be over-carbed.

But if I do dispense will the beer be overcarbed when the tank replaces that missing pressure? Or is it still dependent on temperature, meaning that it will not be over-carbed (using a fridge)?

04-24-2007, 10:12 PM   #14
D2T
Brew Monkey

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May 2006
Morristown, NJ
Posts: 165

Quote:
 Originally Posted by Chillbrook So if I do not dispense the beer will not be over-carbed. But if I do dispense it will not be over-carbed (using a fridge)
See above

04-24-2007, 10:27 PM   #15
johnsma22

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Once your beer has absorbed as much CO2 as it can at the temperature in your fridge it will not absorb anymore, even when you serve. All that is happening when you serve a fully carbonated beer is some volume of CO2 flows into the keg to replace the volume of beer that was just served. No more will go into solution.
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04-24-2007, 10:52 PM   #16
Yuri_Rage
Gritty.

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Southwest
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I never turn mine off. I even left for 3 months, and when I came back, all was well. I use this stuff to check for leaks:

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04-24-2007, 11:20 PM   #17
Chillbrook
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Jan 2007
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Quote:
 Originally Posted by johnsma22 Once your beer has absorbed as much CO2 as it can at the temperature in your fridge it will not absorb anymore, even when you serve. All that is happening when you serve a fully carbonated beer is some volume of CO2 flows into the keg to replace the volume of beer that was just served. No more will go into solution.
It all makes sense now, perfect!

04-24-2007, 11:49 PM   #18
david_42

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Oak Grove, Oregon, USA
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I used to leave mine on, but my new setup has a leak I can't track down. I suspect it is in one of the gages on a secondary regulator, so now I shut the tank off.
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04-25-2007, 03:04 PM   #19
jeffg

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Jan 2006
Boston, MA
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Thanks for the input. I have always been a "just leave the Co2 on" set and forget guy, but this is twice in six months I have mysteriously drained a 20 lb. tank. Pretty annoying since it normally lasts me a couple years before needing refilling. Oh well. Given how well my original keg is maintaining its carbontaion I think I am going to start shutting off the tank between sessions. Seems litle risk in resulting in flat beer given how often I am sampling.

Funny thing about this slow leak was the system worked perfectly for two weeks without any slow drop in pressure, and one morning it was just dead. Teh fact that the nearly empty keg was dead flat with no gas when I pulled the relief valve tells me that my new/used keg is the culprit, which is too bad because I changed all of the seals and have been drinking out of it for three plus weeks.

Kegging is great overall and multiple kegs is even better, but when something goes wrong it is really, really annoying.

Anywho, thanks for the responses.
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04-25-2007, 04:18 PM   #20
johnsma22

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Quote:
 Originally Posted by jeffg Funny thing about this slow leak was the system worked perfectly for two weeks without any slow drop in pressure, and one morning it was just dead.
That's how CO2 in a liquid/vapor state behaves. The pressure in the tank will stay exactly the same, at a given temperature, until all of the liquid in the tank has been vaporized (or leaked out). Once only vapor exists in the tank the pressure will quickly drop to zero.
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