Originally Posted by passedpawn
When we bottle beer, we shoot for "Volumes CO2". The typical beer is 2.4 volumes of CO2.
What is a "Volume of CO2"? If any amount CO2 were given free reign, it would expand to the size of the universe.
Also, why is "Volumes of CO2" used in bottling, but PSI is used in kegging? They are both trying to get to the same thing. Why don't we talk about PSI in bottling?
Volumes are dependent on pressure and temperature. We talk about pressure in the keg, but the temperature is implied. Changing the temperature will change the carbonation at that pressure.
We don't talk about pressure in the bottle since we can't directly apply pressure to the bottle. But it's there, for sure. It also changes with the temperature of the bottle, which is why you want to put it in the fridge before opening. It will cool and absorb more carbonation.