Today in 1973, US Patent 3774820 A was issued, an invention of Homer R. Zucconi, for his “Tapping Device For Beer Kegs.” Here’s the Abstract:

Beer tapping attachments comprising a permanent keg unit including two normally closed spring-biased one-way valves to which unit is detachably secured a valve body which also includes two registering spring biased one-way valves, one connected to a source of air under pressure and the other to a beer spigot. All four valves are yieldably opened when the valve body is connected to the keg unit.