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Large Volume Air Discharge
Air enters the large orifice flows around the annular area between the floats and the valve chamber and discharges into atmosphere.

Surge Dampening
In reaction to an increase in air velocity, the “Anti-Shock” Cartridge (1) closes the large orifice and air is forced through the annular orifices and discharged from the central orifice, resulting in a deceleration of the approaching liquid due to the resistance of air pressure in the valve.

Pressurized Air Release
Subsequent to the filling of a pipeline, liquid enters the valve chamber and the “Anti-Shock” Cartridge (1), and Lower Float (2) are buoyed so that the large orifice is closed by the “Anti-Shock” orifice (1), the valve will then become internally pressurized.

Disentrained air rises through the liquid and accumulates in the valve chamber, when the volume of air is sufficient to displace the liquid, the Lower Float (2) will no longer be buoyant and will gravitate downwards thereby opening the small orifice and simultaneously relieve air in the lower float chamber, allowing accumulated air to escape through the small orifice to be discharged into atmosphere. As air is discharged the liquid raises the Lower Float (2) and re – seals the small orifice and prevents escape of liquid.

Vacuum Relief (Air Intake) – Pipeline Draining
Drainage of liquid from the valve chamber causes the “Anti-Shock”cartridge(1), and Lower Float (2) to gravitate downwards, thereby allowing atmospheric air through the valve to rapidly displace draining liquid in the pipeline and prevent potentially damaging internal negative pressure.