The Valve,restrictor Check, cataloged under National Stock Number 4820-01-008-6639, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. Government technical data includes 20 specifications, cited from the U.S. Government catalog. 1 additional reference document (drawings, advisory and superseded references) is recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4820-01-008-6639 |
| Item Name | Valve,restrictor Check |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Status | ACTIVE |
| Flow Control Device | POPPET |
| Surface Treatment Document and Classification | MIL-S-5002 MIL SPEC SINGLE TREATMENT RESPONSE |
| Connection Style | FLARELESS ALL ENDS |
| Mounting Position | HORIZONTAL |
| Connection Type | THREADED EXTERNAL TUBE ALL ENDS |
| Style Designator | STRAIGHT THRU |
| Material Document and Classification | MIL-S-7720 MIL SPEC SINGLE MATERIAL RESPONSE OVERALL |
| Operating Pressure | 300.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS |
| Aperture Diameter | 0.094 INCHES NOMINAL IN |
| Thread Direction | RIGHT-HAND ALL ENDS |
| Nominal Thread Size | 0.500 INCHES ALL ENDS IN |
| Seat Angle | 12.0 DEGREES ALL ENDS |
| Maximum Operating Temp | 450.0 FAHRENHEIT SINGLE RESPONSE DEGF |
| Disk Loading Method | SPRING |
| Surface Treatment | PASSIVATE |
| Media for Which Designed | AIR SINGLE RESPONSE |
| Thread Class | 3A ALL ENDS A |
| Material | STEEL COMP 303 OVERALL |
| Thread Series Designator | UNIFIED NATIONAL JOINT FINE (UNJF) ALL ENDS |
| 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 |
|---|---|
| 9R2038 | 3/2 Design control — primary reference U.S. Government activity |
NSN 4820-01-008-6639 is a Valve,restrictor Check, classified under FSC 4820, Valves, Nonpowered. Status: active.
Key specifications for 4820-01-008-6639: Flow Control Device: POPPET; Surface Treatment Document and Classification: MIL-S-5002 MIL SPEC SINGLE TREATMENT RESPONSE; Connection Style: FLARELESS ALL ENDS; Mounting Position: HORIZONTAL. 20 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.