Model BGR-1 Pilot Operated Back Pressure Relief Regulator; Body Size 2",; Cf3m Body, 316l SST Loading Chamber; 316l SST Trim, Bc Seat And Diaphragm;V-Tfe Static Seal, Bc O-Ring Dynamic Seal,;Pilot W / Nbr Seat & Bc Diaphragm; 300 Lb Raised Face Flanges; 140-300 Range Spring; SST Tubing, Self Contained Sensing For Positive Pressure Schematic; Opt-40: Construction Per Nace Standard Mr0175