Today in 1966, US Patent 6820775 B2 was issued, an invention of Klaus Meike and Hans Helmut Reichmann, assigned to Schafer Werke Gmbh, for their Electric “Gas-Pressurized Beverage Keg.” Here’s the Abstract:
A beverage container has a cylindrical lower side wall and floor defining a lower beverage chamber and centered on an axis, a cylindrical upper side wall and upper wall centered on the axis and defining an upper pressurized-gas chamber, and an annular partition having an outer edge welded to an upper edge of the lower side wall and a lower edge of the upper side wall and a center part closely juxtaposed with the upper wall of the upper chamber. A tap assembly mounted on the upper-chamber upper wall has a riser tube projecting through the partition center part into a lower region of the lower chamber. An upper protective ring is fitted to the upper part and to the valve assembly and a lower protective ring is fitted to the lower part. The rings and side walls have the same diameters.