4820-00-555-2152 (12Z6107-1)
NSN 4820-00-555-2152 (NIIN 00-555-2152) is a check valve in Federal Supply Class 4820, Valves, Nonpowered — a valve permitting flow in one direction only. Manufacturer part number 12Z6107-1 (Naval Ordnance Standards, CAGE 94135); also referenced as 320WS 1-1/2IN, 420WS1 1-2IPS (The Walworth Company).
Key specs: 400 psi maximum single response operating pressure; full characteristics table below. NIIN assigned January 1961; DEMIL A (none required); ships at 4 lb / 0.0833 cu ft.