5500 Series Rev D Pilot Operated Pressure Relief Vent With Pipe Away; Mates With ASME 150 Flange Connection; 4" Inlet Size; 4" Outlet Size; Aluminum Body And Bolt-In Seat Ring; Fluorocarbon Elastomer (FKM) Actuator Diaphragm, Pilot Seat, And Pallet Diaphragm; 18.1" - 36.0" wc Pressure Spring Range; Standard: Internal Sensing With Pilot Exhaust To Main Valve Outlet And Backflow Preventer