Fire Hydrant Relief Valve Inlet Size 2 1/2 in Capacity 500 gpm @ 45 fps Inlet Pressure 0 to 300 psi Pilot Adjustment Range 20 to 175 psi Body Material Cast Iron Connection Type FNST Swivel Seal Material Buna N Quad Seal Stem Material Stainless Steel AISA303 Diaphragm Material Nylon Reinforced Buna N Seat Material Brass Control Circuit Fixed Orifice Application Installed on fire hydrants to provide temporary relief protection to a water system