Pressure versus temperature

[JayH]

Hey guys,

If I use the appropriate pressure to acheive 2.5 volumes of CO2 at 67 degrees in a keg, then disconnect it and store it at 67 for a little bit, when I drop it to 40 (gas disconneted) will it still have 2.5 volumes in that keg?

Thanks,

Jay

[Mylo]

Provided there aren't any leaks.... yes.


Mylo

[boobookittyfuk]

as the temperature drops the volume of CO2 will change

[RJH311]

it depends. if you have the beer fully carbonated at the warmer temp then yes, your carbonation will hold. but if you're trying to carbonate the beer and just put it at the pressure you need, disconnect it, and bring the temperature down then no, you wont have the right amount of carbonation. either fully carbonate your beer then chill it or carbonate your beer at the lower temp.

[calpete]

Mylo and RJH are correct. Assuming no leaks, then there will be no change in volumes of dissolved CO2. The head-space pressure will go down with lower temp, but the amount of CO2 in the beer will be unchanged. That is, your beer will be just as carbonated as it was when you disconnected it from the gas at the warmer temp.

Of course, as you begin to dispense beer at the cooler temp, the carbonation can change depending on the pressure-temp combo you use to dispense.

[boobookittyfuk]

if the keg is completely full, then the temperature would have no effect on the amount of dissolved CO2.....if it had 2.5 volume at 70F it would still have 2.5 volume at 38F.

this is confusing: if you had a half full keg...thus more head space in the keg...when cooling the temperature from 70F to 38F the gas pressure would go down, but wouldn't the volume of the beer change too? and therefore the amount of dissolved CO2 would remain constant?

after all i don't think these changes are noticable....

[Bugeater]

The answer is no, BooBoo. At warmer temperatures it takes higher head pressure to force and hold a given volume of CO2 in solution than at a lower temperature. Thus when you chill the keg and the head pressure drops the same volume of CO2 stays in the beer because it doesn't take as much pressure to hold it there.

Wayne