Model 1049 Rev A Pilot Operated Vent Valve; Carbon Steel Body With Flame Screen; 6" Inlet X 8" Outlet Mates With ASME 150 Flanged End Connections; Fluorocarbon Elastomer (FKM) Soft Seats; Option 4: Internal Sensing With Pilot Exhaust To Atmosphere And Backflow Preventer; Fluorocarbon Elastomer (FKM) Actuator Diaphragm; 36.1" - 41.7" wc Pressure Range