Air Valves from HMA Flow & Industrial are available in three basic configurations: Air Release Valves, Air/Vacuum Valves and Combination Air Valves. Correct sizing and location of all three types are critical. Every high point greater than one pipe diameter, where the pipeline converts from a positive grade to a negative grade, requires an air valve. Even minimal high points with small air pockets can cause serious surge problems and reduce line efficiency. In addition, it is recommended that air valves be installed every half mile or 2 500 feet on straight horizontal runs (AWWA M51).

Air/Vacuum Valves, sometimes referred to as large orifice valves, are used to exhaust large quantities of air upon system start-up, as well as allowing air to re-enter the line upon system shutdown or system failure. As water enters the valve, the float will rise, closing the discharge port. The valve will remain closed until the system pressure drops to near zero psi. It will not open to release any accumulation of air while the system is under pressure.