The Valve,safety Relief, cataloged under National Stock Number 4820-01-147-4951, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. The manufacturer of record is Northrop Grumman Systems Corporation. Government technical data includes 20 specifications, cited from the U.S. Government catalog. The record lists 1 manufacturer part number for this item, enabling identification through both NSN and commercial part number lookups. 3 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4820-01-147-4951 |
| Primary Part Number | GV500HW4A12-77 |
| Item Name | Valve,safety Relief |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Manufacturer | Northrop Grumman Systems Corporation |
| Status | ACTIVE |
| Flow Control Device | POPPET |
| Connection Style | GASKET SEAL (TUBE) FIRST END |
| Connection Type | THREADED EXTERNAL TUBE FIRST END |
| Style Designator | STRAIGHT THRU |
| Material Document and Classification | QQ-A-225/6,T4 FED SPEC SINGLE MATERIAL RESPONSE OVERALL |
| Operating Pressure | 200.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS |
| Thread Direction | RIGHT-HAND FIRST END |
| Nominal Thread Size | 0.438 INCHES FIRST END IN |
| Maximum Operating Temp | 250.0 FAHRENHEIT SINGLE RESPONSE DEGF |
| Disk Loading Method | SPRING |
| Surface Treatment | ANODIZE LOCATION NOT OTHERWISE SPECIFIED |
| Media for Which Designed | FUEL/OIL, HYDROCARBON SECOND RESPONSE |
| Media for Which Designed | HYDROGEN FOURTH RESPONSE |
| Media for Which Designed | AMMONIA, GASEOUS THIRD RESPONSE |
| Media for Which Designed | GAS, INERT FIRST RESPONSE |
| Thread Class | 3A FIRST END A |
| Material | ALUMINUM ALLOY 2024 OVERALL |
| Thread Series Designator | UNF FIRST END |
| Opening Pressure Setting | 12.0 POUNDS PER SQUARE INCH LBS |
| 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 |
| Part Number | Manufacturer |
|---|---|
| GV500HW4A12-77 | Northrop Grumman Systems Corporation (USA) |
| Reference | Meaning |
|---|---|
| GV500HW4A12-37 | 5/9 Secondary reference Northrop Grumman Systems Corporation |
| 537A-4D-12 | 5/9 Secondary reference U.S. Government activity |
| 577A-4D-12 | 3/2 Design control — primary reference U.S. Government activity |
NSN 4820-01-147-4951 is a Valve,safety Relief, manufactured by Northrop Grumman Systems Corporation, classified under FSC 4820, Valves, Nonpowered. Status: active.
NSN 4820-01-147-4951 has 1 manufacturer part number on file: GV500HW4A12-77 (Northrop Grumman Systems Corporation).
Key specifications for GV500HW4A12-77: Flow Control Device: POPPET; Connection Style: GASKET SEAL (TUBE) FIRST END; Connection Type: THREADED EXTERNAL TUBE FIRST END; Style Designator: STRAIGHT THRU. 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.