4820-00-202-6819 (S4824-313854)
NSN 4820-00-202-6819 (NIIN 00-202-6819) is a check valve in Federal Supply Class 4820, Valves, Nonpowered — a valve permitting flow in one direction only. Manufacturer part number S4824-313854 (Naval Ship Systems Command, CAGE 80064); also referenced as 3600-137 (Electric Boat Corporation); B/MX5725 (Derbyshire Machine & Tool Co).
Key specs: 500 psi maximum single response operating pressure; full characteristics table below. NIIN assigned January 1963; DEMIL A (none required); unit of issue EA (each), $1,198.55 gov standard price; ships at 15.458 lb / 0.1467 cu ft.