air tap

air vent

In a water distribution system, a vent for releasing trapped air; usually located at the highest point in the system.
References in periodicals archive ?
This is music at its rawest form; get ready to hum and air tap along to the artists' heartfelt, reflective, folk-inspired tunes.
He was forced to run a cleaning rod from the muzzle through the air tap and into the transfer port, then hammer the rod until two lead plugs fell out the back of the gun.
M2 EQUITYBITES-January 6, 2016-Gulf Air taps Sabre to streamline operations