ARO PF20A-ACP-SUB-B Pump Part Exploded View Diagram & 2" Metallic Flap Valve Repair Parts PDF Manual. Air Section Service Kit: 637421, Fluid Section Service Kit: 637310-UB, Major Valve Service Assembly: 637374-2 & Cartridge Assembly: 66307-U Available. Replacement Diaphragm, Seat, Flap, Bumper, O-Ring, Seal, Rod, Manifold, Washer, Bolt, Nut, Gasket, Sleeve, Screw, Pipe Plug, Bushing, Center Body, Plate, Spool, Ground Lug, Valve, Tube, Muffler.