Model 1049 Pilot Operated Vent Valve; Carbon Steel Body With Flame Screen; 3" Inlet X 4" Outlet ASME Class 150# Rf Flanges; Epdm Soft Seats; Option 5: With Internal Sensing, SST Pilot Filter Element, Pilot;Exhaust To Atmosphere, With Backflow Preventer To Prevent Back Flow;Through Main Valve And Pilot, And With Field Test Conections; Epdm Actuator Diaphragm; 18.1" - 36.0" Wc; Rev Level A