There are two methods used to carbonate a keg:
- Set and forget
- Force carbonation
In the first method, the keg's PSI is set to a value determined by a kegging chart and is left at that PSI for the duration of the beers life. Some time after 1-2 weeks, the beer is fully carbonated and the exact volumes of CO2 in the beer is known.
In the second method, the keg's PSI is set to around 30 and left there for 24-36 hours, before being brought down back to "serving pressure" which is typically the same value as set in the first method. Some people may purge the keg before dropping the PSI, and others may shake the keg.
I have heard that when we force carbonate, it is not possible to know the exact volumes of CO2 in the beer. Is this true? I would think that the beer would eventually equalize out to the PSI at the serving temperature. If this is not true - why isn't it? If I set the PSI to 30 for only 1 hour (instead of 48), does the same apply? How about 1 minute?