5500 Series Rev D Pilot Operated Pressure Relief Vent With Pipe Away; Mates With PN16 Flange Connection; 2" Inlet Size; 2" Outlet Size; Aluminum Body And Bolt-In Seat Ring; EPDM Actuator Diaphragm, Pilot Seat, And Pallet Diaphragms; 1.2" - 3.9" wc Low Pressure Pressure Spring Range With Air Assist; Standard: Internal Sensing With Pilot Exhaust To Main Valve Outlet And Backflow Preventer