Question about pressure and temp

[rniles]

Ok. My target pressure is 2.52

The beer is at 65 degrees and I pressurize to 29psi AND then cooled the beer down to 43 degrees, would my beer still be at 2.52?

If not, what would it be? What variables change?

 

[Reno_eNVy]

Not quite. Once your beer cools down to 43 degrees it will continue to carbonate to the volume of CO2 you get at 43 degrees and 29psi.

Just remember: PV = nRT

Pressure (P) is directly related to temperature (T) and thus lower temperature means lower pressure, so the CO2 tank is going to keep pumping in CO2 until it's reached the set psi.



EDIT: Just looked it up on BeerSmith. To get 2.53 volumes of CO2 you're going to want to set it to ~14psi. Don't worry about what temperature it's going to be once you initially hook it up to gas. It's going to take 10 days or so for that sucker to carbonated anyway so you have plenty of time for your beer to get cold

 

[JuanMoore]

I'm assuming that by pressure you mean carbonation (in volumes of CO2). If you put 29psi on a keg that's 65F, CO2 will dissolve into the beer over the course of a couple of weeks until it reaches equilibrium at ~2.52 vol. If you disconnect the gas and then change the temperature of the keg, the pressure in the headspace will change, but the carbonation level will remain a constant 2.52 vol. If you leave the gas connected and change the temperature, the carbonation level will then start to move towards the equilibrium of that new pressure/temperature combination. If you chill the keg to 43F, you would then reduce the pressure to 14psi to serve in order to maintain the same 2.52 vol of carbonation.

 

[rniles]

Thank you both - I did forget to mention in my scenario that I intended to disconnect the CO2. - but more than that, I was curious as to what the answer would be.

Currently, I'm trying to decide whether to kegorator the fridge or buy a freezer to make a keezer. I've just kegged my first batch. I thought I would bring the C02 to 29 PSI and put in fridge ...then tomorrow when the beer is 43 degrees, then put 14 psi of pressure on the beer, and do that once or twice each day (as opposed to leaving the CO2 connected all the time since I'm not sure if I want to drill holes in the fridge yet).

 

[camiller]

Thank you both - I did forget to mention in my scenario that I intended to disconnect the CO2. - but more than that, I was curious as to what the answer would be.

Currently, I'm trying to decide whether to kegorator the fridge or buy a freezer to make a keezer. I've just kegged my first batch. I thought I would bring the C02 to 29 PSI and put in fridge ...then tomorrow when the beer is 43 degrees, then put 14 psi of pressure on the beer, and do that once or twice each day (as opposed to leaving the CO2 connected all the time since I'm not sure if I want to drill holes in the fridge yet).

Put the co2 tank inside the fridge. Just bringing the headspace to 29psi then disconnecting and putting in the fridge isn't going to do much. Just set to 14psi (make sure you don't have any leaks) and put the whole rig in the fridge for two weeks.

 

[JuanMoore]

put the co2 tank inside the fridge. Just bringing the headspace to 29psi then disconnecting and putting in the fridge isn't going to do much. Just set to 14psi (make sure you don't have any leaks) and put the whole rig in the fridge for two weeks.

+1
Or just leave everything connected outside of the fridge at 29 psi for two weeks.