The Valve,check, cataloged under National Stock Number 4820-00-121-9657, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. Government technical data includes 19 specifications, cited from the U.S. Government catalog. 2 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4820-00-121-9657 |
| Item Name | Valve,check |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Status | ACTIVE |
| Flow Control Device | DISK |
| Nominal Pipe Size Accommodated | 0.250 INCHES SECOND END IN |
| Connection Style | FLARED (TUBE) FIRST END |
| Connection Style | GASKET SEAL (BOSS) SECOND END |
| Style Designator | STRAIGHT THRU |
| Nominal Outside Diameter Tube Accommodated | 0.375 INCHES FIRST END IN |
| Nominal Outside Diameter Tube Accommodated | 0.250 INCHES SECOND END IN |
| Operating Pressure | 20.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS |
| Thread Direction | RIGHT-HAND ALL ENDS |
| Nominal Thread Size | 0.438 INCHES SECOND END IN |
| Nominal Thread Size | 0.562 INCHES FIRST END IN |
| Seat Angle | 37.0 DEGREES FIRST END |
| Face to Face Distance | 1.906 INCHES IN |
| Thread Class | 3A FIRST END A |
| Thread Class | 2B SECOND END |
| Thread Quantity Per Inch | 24 SECOND END |
| Thread Series Designator | UNS SECOND END |
| Thread Series Designator | UNF FIRST END |
| Valve Operation Method | AUTOMATIC |
| Acquisition Status | ACTIVE |
| DEMIL Code | DEMIL A — No Demilitarization Required |
| Hazard | No hazard code in the DLA record (HMIC N) |
| Criticality Code | X |
| Reference | Meaning |
|---|---|
| 1232850 | 5/9 Secondary reference The Boeing Company |
| 1232850 | 3/2 Design control — primary reference U.S. Government activity |
NSN 4820-00-121-9657 is a Valve,check, classified under FSC 4820, Valves, Nonpowered. Status: active.
Key specifications for 4820-00-121-9657: Flow Control Device: DISK; Nominal Pipe Size Accommodated: 0.250 INCHES SECOND END IN; Connection Style: FLARED (TUBE) FIRST END; Connection Style: GASKET SEAL (BOSS) SECOND END. 19 specifications are documented in the U.S. Government catalog.
No hazard code in the DLA record (HMIC N). Hazard information on this page is shown exactly as it appears in the DLA record.
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-16.
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-18.