Appnote: Brewing with Alicat

Brewing with Alicat

For many people around the world who consume alcohol, beer is the drink of choice. Whether ale or lager, bubbles of carbon dioxide can be the not-so-subtle difference between a refreshing pint and a flat disappointment. The average beer drinker may know when their suds’ carbonation is just right, but they might not know the complex process that was necessary to get just the right amount of bubbles in their glass.

Fermentation process

Commercial carbonation of beer typically involves sparging carbon dioxide into the bottom of a brite tank (a vessel containing chilled and filtered beer). The colder the beer is, the more CO2 it can hold in solution. At a given temperature the amount of carbon dioxide dissolved in the beer directly depends on the partial pressure of the CO2 in the tank. By forcing carbon dioxide through a porous stone, bubbles are created at the bottom of the tank. These bubbles increase the surface area of gas that is in contact with the beer, speeding up the dissolution of CO2 into the beer.

While temperature is controlled by other means, control over the CO2 sparged into the brite tank is simple with Alicat mass flow controllers. Depending on the brewer’s preference, either the pressure or the flow rate of CO2 delivered to the carbonation stone can be controlled with an Alicat mass flow controller. While most mass flow controllers handle only a single parameter, Alicat mass flow controllers can report pressure, mass flow, volumetric flow and temperature simultaneously. Controlling the mass flow rate confers the advantage of knowing exactly how much mass (or ‘volumes’) of CO2 will be in the tank after a given period of time. Using pressure as the control variable is the classic method of carbonation; when the pressure of the brite tank’s headspace is equal to the pressure delivered to the carbonation stone, then the beer has reached equilibrium and carbonation should be complete, or close to complete.

Alicat’s mass flow controllers also can be ordered with a totalizer option.  The totalizer option allows the unit to track the total mass of volume of a given gas that has been delivered. With totalizer functionality, the total number of desired CO2 volumes can be pre-programmed to be dispensed at a specified flow rate. Using this method, both the amount of CO2 and the time period over which it is delivered are under control, keeping two process variables automated and consistent at one time.

Alicat controllers provide convenient automation for the carbonation process, saving time and money while creating a more consistent, predictable brewing process.