Force carbonation

Force carbonation is the process of dissolving carbon dioxide into beer under pressure, typically inside a sealed keg connected to a CO2 tank through a regulator, rather than waiting for residual yeast to produce CO2 from priming sugar. Setting the regulator to a specific pressure at a known beer temperature drives a predictable, repeatable level of carbonation into the beer over a period of days, or faster with agitation.

The relationship between temperature, pressure, and the resulting carbonation level is well established, so brewers use a reference chart to pick the PSI setting that matches their target carbonation for a given serving temperature. This makes it easy to dial in a crisp, highly carbonated lager or a softer, lower-carbonation ale using the same equipment, just different settings.

A common mistake is expecting carbonation to happen instantly at any pressure, when it actually takes time for CO2 to dissolve fully into beer, especially at cold serving temperatures without shaking or rocking the keg to speed things along. Setting the pressure too high for an extended serving period is another frequent issue, since it can leave beer overcarbonated and gushing at the tap even though the fill went smoothly.