Abstract: In order to release gas dissolved in a liquid such as beer the liquid is injected as a spray into an agitation chamber having a liquid outlet at one end and a gas outlet at the other end. The gas outlet is controlled by a valve. Electrical contacts are provided within the chamber for monitoring the liquid level therein. When liquid in the chamber rises to a level which covers both contacts the gas outlet valve will be closed and liquid continues to enter the chamber until prevented from so doing by the gas cushion. When the liquid level drops below the electrical contacts the gas valve is opened.