Model 1049 Rev A Pilot Operated Vent Valve; Stainless Steel Body; 3" Inlet X 4" Outlet Mates With ASME 150 Flanged End Connections; FFKM 2 Soft Seats; Option 7: Internal Sensing With Pilot Exhaust Tubed To Main Valve Outlet And Rotometer To Purge Pilot Sense And Discharge Lines; BUNA-N Actuator Diaphragm With FEP Liners; 41.8" - 86.0" wc Pressure Range; Special With Backflow Preventor