Today in 1959, US Patent 2906435 A was issued, an invention of Frank Nichols, for his “Air Pressure Actuated Beer Dispenser and Coil Cleaner.” There’s no Abstract, although in the description it includes this summary:

This invention relates to beer dispensing apparatus in which beer is on tap continuously, and in particular, beer dispensing apparatus where beer is supplied from kegs or other containers to cooling coils and taps by filtered air under pressure continuously and in which the coils are cleaned by a detergent suspended in water and wherein the moisture is removed by air under pressure.

The purpose of this invention is to provide beer dispensing apparatus in which all foreign tastes or flavors due to leakage of oil, gases, and the like into the system are eliminated.