4820-01-054-6010 (7-551-0810)
NSN 4820-01-054-6010 (NIIN 01-054-6010) is a check valve in Federal Supply Class 4820, Valves, Nonpowered — a valve permitting flow in one direction only. Manufacturer part number 7-551-0810 (Bucher Municipal Gmbh, CAGE D0589); also referenced as 4K33N3WS (Danfoss Fluid Power IncEasley Opn).
Key specs: 2000 psi maximum single response operating pressure; full characteristics table below. NIIN assigned January 1978; DEMIL A (none required).