Abstract: A beverage dispensing system has a container from which beverage is to be dispensed by a gaseous mixture of air and carbon dioxide from passage 31. Air pressure for dispensing is derived from compressor 7. Carbon dioxide 11 is capable of communication with the container by way of a diaphragm valve 14 which normally closes communication between the carbon dioxide source 11 and the container. Diaphragm 16 of valve 14 is responsive to variations in pressure derived from compressor 7 so that the valve 14 opens communication between the carbon dioxide source 11 and the container when mixed gases are demanded. The diaphragm 16 controls displacement of a spool 19 which determines the opening and closing of communication between the carbon dioxide 11 and the container. A chamber 17 communicates with the air line 9 while a chamber 18 communicates with the container and is capable of communication with the carbon dioxide 11 under control of the spool 19.