The Anti-Siphon is used on above ground storage tanks to prevent spillage and to avoid other potential hazards. In the event a siphon occurs due to rupture in the product pipe line, the valve will automatically stop the product flow. The valve is a normally closed check valve and will resist hydrostatic head pressure and prevent siphoning. The anti-siphon valve features a rust resistant epoxy coated cast iron body, precision machined bronzed seat, Bunga-N seals and is also available with pressure relief valve to relieve thermal expansion (Model 620PR).