Air Vent Valve bleed release valve and vaccum breaker valve ATR-S port sizes 1/2", 3/4" or 1" inch BSP or NPT thread pressure rated to 10 Bar. This Stainless Steel Air Vent (Air Release Valve) mechanically and efficiently automatically evacuates any air or gasous media trapped within any liquid pipe system helping to reduce the noise or the interference that is caused by trapped air. This ATR valve will automatically release any vacuum or negative pressure in the pipeline. The ATR-Sair vent valve must be installed vertically (upright) and is recomended to be installed at the highest point of the pipe line system. Maximum working pressure 20 Bar, Seat test pressure 21 bar, Body test pressure 32 bar, maximum working temperature +80ºC.