MJP approved air valves

Air valves are hydromechanical devices with an internal float mechanism designed to release trapped air and wastewater gases during filling and operation of a piping system.

There are three types of air valves primarily installed in water supply systems: automatic air valves, air and vacuum valves and combination air valves. Read more about why air appears in pipelines, the function of air valves, and where to install air valves on the pipeline.

As air is fed into the reservoir through a compressor, it pushes against the walls of the area. Once the pressure becomes strong enough, it compresses springs beneath the reservoir, pushing the diaphragm down. This, in turn, causes the valve stem to press downwards and close the valve.

Air valves are installed in pipelines at various locations, including:

High points: Combination air valves are installed at high points in the pipeline.

Long runs: Air release or combination valves are installed at 1,250 to 2,500 ft intervals on long horizontal runs.

Long ascents: Air/vacuum valves are installed at 1,250 to 2,500 ft intervals on long ascents.

Long descents: Combination air valves are installed at 1,250 to 2,500 ft intervals on long descents.

Changes in slope: Air/vacuum valves are installed at decreases in an up slope, and combination air valves are installed at increases in a down slope.

Transient locations: Combination/slow-closing devices or vacuum breakers/air releases are installed at transient locations.

Flow meters: Air releases are installed upstream of flow meters.

Pumps: Air/vacuum/slow-closing devices or throttling devices are installed at well or vertical turbine pumps.

Adjacent to other valves: Air release valves are installed adjacent to mainline valves.

Downstream of pumps: Air valves are installed downstream of pumps.

Air valves are installed to prevent vacuum conditions and air-related surges by admitting and exhausting air. They should be installed vertically, ideally directly on top of the pipe. However, if the pipeline is located under a roadway, the air valve may need to be mounted in a separate vault.