Today in 2005, US Patent EP 1295845 B1 was issued, an invention of Chang Kung-Chien, for his “Safe Device For a Double Valve Arrangement For Beer Keg.” There’s no Abstract, although in the description it includes this summary:

This invention relates to a double valve arrangement used for a pressurized beer keg, said arrangement comprises a safety device in order to prevent a valve body popped out of the keg under pressure causing unintended personal injury, or when the dismount is handled by somebody who is unauthorized to do so.