The Role of CO2 in Beer Kegs
The process begins with CO2 being attached to a primary regulator. This regulator is responsible for feeding the keg with CO2. The pressure from the CO2 pushes down on the beer, forcing it to move upwards through the keg spear. From there, the beer flows out through the beer coupler. Depending on the setup, it either goes into a temporary draft system, like a jockey box, or into another type of system, such as a long draw (or direct draw) draft system.
In the case of a long draw draft system, the setup is similar. Gas feeds into the keg, pushing the beer through the keg into the beer line. It then enters the main trunk line. This trunk line could be a glycol or air-chilled system that leads into barrier tubing. The barrier tubing, which could be a coil or a cold plate similar to what is seen in a jockey box, ultimately channels the beer to the beer faucet.