Today in 1987, US Patent 4665940 A was issued, an invention of Charles S. Jacobson, for his “Container Fitting.” Here’s the Abstract:

A fitting for a container of draft beer or the like includes a first valve for permitting pressurized gas to be injected into the container and a second valve for permitting beer to be dispensed from the container. Both valves are urged to their closed positions by inexpensive elastomeric springs which also serve to hold certain components of the fitting in assembled relation. A coupler attaches the fitting to the container and enables the container to be used with Sankey-type taps.