Kegging and carbonation
From fermenter to tap: a short guide to getting beer into a keg and making it fizzy.
Why keg
Kegging saves the work of cleaning and filling dozens of bottles. A 19 litre keg is filled in one go, the beer is carbonated with CO2 from a cylinder, and you can pour a glass whenever you like.
What you need
A keg (a Cornelius or ball-lock keg is the usual home choice, and a sanke keg is the usual commercial one), a CO2 cylinder with a regulator, gas and beer lines, and a tap or a coupler. A fridge or kegerator keeps the beer at serving temperature.
Clean and sanitise
Clean the keg and fittings with a brewery cleaner, rinse, then sanitise. Empty and refill the keg with sanitised water if you want, then push the sanitiser out with CO2 so the keg is full of gas, not air.
Fill and purge
Transfer the beer from the fermenter with as little splashing as possible. Seal the keg, then purge the headspace with a few short bursts of CO2 to push out the oxygen that would otherwise stale the beer.
Carbonate
Chill the keg to serving temperature, then set the regulator to the pressure the carbonation calculator gives for that temperature and the volumes of CO2 you want. At 4 C and 2.4 volumes that is roughly 11 PSI. It takes about a week to reach equilibrium. To go faster, you can raise the pressure for a day or two, but it is easy to overshoot, so measure.
Serve
When the beer is carbonated, serve at a lower pressure, or use long beer lines, so the beer does not foam. If it foams, check the temperature, the pressure and the length of the lines.
Keeping it safe
Chain the cylinder upright, use a regulator rated for the cylinder, and check the keg's pressure rating. Release all the pressure before opening any keg. If you have a sanke keg with a screw-in valve, read how to open it safely.