Model 1049 Rev A Pilot Operated Vent Valve; Carbon Steel Body With Flame Screen; 3" Inlet X 4" Outlet, Mates With ASME 150 RF Flanged End Connections; Fluorocarbon Elastomer (FKM) Soft Seats; Standard Configuration With Internal Sensing And Pilot Exhaust To Atmosphere; Fluorocarbon Elastomer (FKM) Actuator Diaphragm; 36.1" - 41.7" wc Pressure Range