Automatic Air Release Valve

An automatic air release (AR) valve is installed at high points in hydrant piping to vent trapped air without manual intervention. In pump rooms and vertical risers, air pockets can accumulate and cause cavitation, noisy operation, and reduced discharge pressure.

The AR valve uses a float mechanism: when air collects, the float drops and the valve opens to release air; once water reaches the chamber, the float rises and seals the outlet. This protects pump performance and stabilizes pressure during start/stop cycles.

AR valves are strongly recommended wherever piping rises above pump level or where long vertical runs exist, even if not explicitly mandated by NBC.