The Valve,safety Relief, cataloged under National Stock Number 4820-01-257-8680, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. Government technical data includes 23 specifications, cited from the U.S. Government catalog. 4 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4820-01-257-8680 |
| Item Name | Valve,safety Relief |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Status | ACTIVE |
| Flow Control Device | DISK |
| Connection Style | FLARED (TUBE) SECOND END |
| Connection Style | PLAIN (PIPE) FIRST END |
| Connection Type | THREADED EXTERNAL TUBE SECOND END |
| Connection Type | THREADED EXTERNAL PIPE FIRST END |
| Style Designator | ANGLE |
| Features Provided | PRESSURE TIGHT OUTLET SIDE |
| Thread Direction | RIGHT-HAND ALL ENDS |
| Nominal Thread Size | 0.875 INCHES SECOND END IN |
| Nominal Thread Size | 0.500 INCHES FIRST END IN |
| Seat Angle | 45.0 DEGREES SECOND END |
| Disk Loading Method | SPRING |
| Media for Which Designed | REFRIGERANT 22 SECOND RESPONSE |
| Media for Which Designed | REFRIGERANT 12 FIRST RESPONSE |
| Media for Which Designed | REFRIGERANT R-502 THIRD RESPONSE |
| Thread Class | 3A SECOND END A |
| Material | COPPER ALLOY BODY |
| Material | COPPER ALLOY FLOW CONTROL DEVICE |
| Material | COPPER ALLOY SEAT |
| Thread Series Designator | UNIFIED NATIONAL JOINT FINE (UNJF) SECOND END |
| Thread Series Designator | NPT FIRST END |
| Opening Pressure Setting | 350.0 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 |
| Reference | Meaning |
|---|---|
| B527E | D/9 Drawing number reference only Henry Technologies, Inc. |
| 527E-350PSI | 3/9 Design control — primary reference Henry Technologies, Inc. |
| B527-350 | 5/9 Secondary reference Henry Technologies, Inc. |
| 527-350PSI | 5/9 Secondary reference Henry Technologies, Inc. |
NSN 4820-01-257-8680 is a Valve,safety Relief, classified under FSC 4820, Valves, Nonpowered. Status: active.
Key specifications for 4820-01-257-8680: Flow Control Device: DISK; Connection Style: FLARED (TUBE) SECOND END; Connection Style: PLAIN (PIPE) FIRST END; Connection Type: THREADED EXTERNAL TUBE SECOND END. 23 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.