5500 Series Rev D Pilot Operated Pressure Relief Vent With Pipe Away; Mates With ASME 150 Flange Connection; 2" Inlet Size; 2" Outlet Size; Carbon Steel Body With 316 Stainless Steel Bolt-In Seat Ring; FFKM 1 Pilot Seat With FEP Pallet And Actuator Diaphragms; 18.1" - 36.0" wc Pressure Spring Range; Standard: Internal Sensing With Pilot Exhaust To Main Valve Outlet And Backflow Preventer; Special Welded Spool Piece and Upper Body Joint