Today in 1971, US Patent 3625399 A was issued, an invention of Noel D. Heisler, assigned to the Schlitz Brewing Co., for his “Automatic Carbonated Beverage Dispensing System.” There’s no Abstract, although in the description it includes these claims:

In general, the invention is directed to an electrical release or dispensing system for a plurality of carbonated beverages stored in suitable containers where it is desirable at a remote distance therefrom to initiate the dispensing of the beverages from another and successive container when the container from which the beverage being dispensed is empty. The system provides a header which is connected to the containers to be emptied by separated conduits in which are located solenoid liquid valves. These valves are separately actuated from a selector control unit to open a respective conduit from a container to the header and then to to a tap. A second header is connected to a source of Co gas and flow of gas from the header to the containers are through separate conduits to each container. Solenoid fluid valves are located in each gas conduit and are individually actuated to control the flow of gas to the container being tapped. The opening of a respective fluid solenoid valve occurs simultaneously with the opening of a corresponding liquid valve An important feature of the invention is that the dispensing valves are opened by momentary high surge of current to seize the solenoid armature and are held in the open position by a low holding current. The holding current consumes less power and consequently gives off less heat. In an alternative construction, the liquid dispensing valves may each be dual winding units having an opening winding and a holding winding. The holding winding draws a lesser current and consequently also minimizes generation of heat. Excessive heat is deleterious to the carbonate beverage being dispensed.