Today in 1969, US Patent 3454018 A was issued, an invention of Maurice Ruddick, for his “Apparatus For Processing Beer Kegs.” There’s no Abstract, although in the description it includes this summary:

Apparatus for automatically washing beer kegs or like containers comprises a head which is applied to the bung hole or other opening of the container with the container inverted, pipes connected to the head for the supply of washing water and detergent for washing the container and steam for lblowing the water and detergent out of the container after washing and a drainage pipe through which the discharged water and subsequently the steam ows from the container. The supply of water, detergent and steam is controlled by pneumatically operated valves in the pipes and the supply of air to control these valves is controlled by solenoid valves operated by an electrical sequence controller. The drainage pipe has an electrical temperature sensitive device electrically connected to the sequence controller which prevents the sequence controller from operating said Valves to cause further washing water or detergent to be supplied tothe container until all previous liquid has been blown out by the steam and there is a flow of steam through the drainage pipe over the temperature sensitive device.