Today in 1939, US Patent 2143565 A was issued, an invention of Raymond G. Minea, for his “Beer Stabilizer Coil Control.” There’s no Abstract, although in the description it includes this summary:

My invention relates to an improvement in regulator valves, particularly adapted for use in dispensing beer, ale, or the like; and to a dispensing apparatus for controlling the flow of the beer or other liquid through the valve.