The Valve,safety Relief, cataloged under National Stock Number 4820-01-178-2939, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. Government technical data includes 24 specifications, cited from the U.S. Government catalog. 2 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog.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 | 4820-01-178-2939 |
| Item Name | Valve,safety Relief |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Status | ACTIVE |
| Flow Control Device | POPPET |
| Surface Treatment Document and Classification | MIL-A-8625,TYPE 2 MIL SPEC SINGLE TREATMENT RESPONSE LOCATION NOT OTHERWISE SPECIFIED |
| Connection Style | FLARELESS (TUBE) ALL ENDS |
| Connection Type | THREADED EXTERNAL TUBE ALL ENDS |
| Style Designator | STRAIGHT THRU NOTE: TO BE USED FOR VALVE BODIES OF ONE SECTION ONLY. |
| Material Document and Classification | QQ-A-225/6 FED SPEC SINGLE MATERIAL RESPONSE BODY |
| Material Document and Classification | QQ-A-225/6 FED SPEC SINGLE MATERIAL RESPONSE FLOW CONTROL DEVICE |
| Operating Pressure | 140.0 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 | 12.0 DEGREES ALL ENDS |
| Maximum Operating Temp | 275.0 FAHRENHEIT SINGLE RESPONSE DEGF |
| Surface Treatment | ANODIZE LOCATION NOT OTHERWISE SPECIFIED |
| Media for Which Designed | OIL, HYDRAULIC SINGLE RESPONSE |
| Thread Class | 3A ALL ENDS A |
| Thread Quantity Per Inch | 20 SECOND END |
| Thread Quantity Per Inch | 18 FIRST END |
| Material | ALUMINUM ALLOY 2024 FLOW CONTROL DEVICE |
| Material | ALUMINUM ALLOY 2024 BODY |
| Thread Series Designator | UNIFIED NATIONAL JOINT FINE (UNJF) ALL ENDS |
| Opening Pressure Setting | 120.0 POUNDS PER SQUARE INCH LBS |
| Valve Discharge Flow Rate | 1.0 GALLONS PER MINUTE |
| 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 |
|---|---|
| TE20521 | D/9 Drawing number reference only U.S. Government activity |
| 2R2934 | 3/2 Design control — primary reference U.S. Government activity |
NSN 4820-01-178-2939 is a Valve,safety Relief, classified under FSC 4820, Valves, Nonpowered. Status: active.
Key specifications for 4820-01-178-2939: Flow Control Device: POPPET; Surface Treatment Document and Classification: MIL-A-8625,TYPE 2 MIL SPEC SINGLE TREATMENT RESPONSE LOCATION NOT OTHERWISE SPECIFIED; Connection Style: FLARELESS (TUBE) ALL ENDS; Connection Type: THREADED EXTERNAL TUBE ALL ENDS. 24 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.