The Valve,safety Relief, cataloged under National Stock Number 4820-01-491-9965, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. Government technical data includes 15 specifications, cited from the U.S. Government catalog. 1 additional reference document (drawings, advisory and superseded references) is recorded in the U.S. Government catalog. 1 item shares a part number with this NSN in the catalog (possible match — not a government interchangeability claim). Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4820-01-491-9965 |
| Item Name | Valve,safety Relief |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Status | ACTIVE |
| Flow Control Device | POPPET |
| Connection Style | PLAIN (SCREW-IN CARTRIDGE) FIRST END |
| Connection Type | THREADED INTERNAL PIPE FIRST END |
| Style Designator | SCREW-IN CARTRIDGE |
| Operating Pressure | 58.5 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS |
| Thread Direction | RIGHT-HAND FIRST END |
| Nominal Thread Size | 0.500 INCHES FIRST END IN |
| Maximum Operating Temp | 250.0 FAHRENHEIT SINGLE RESPONSE DEGF |
| Material | COPPER ALLOY BODY |
| Material | RUBBER SYNTHETIC PACKING |
| Material | PLASTIC SILICONE SEAT |
| Thread Series Designator | NPT FIRST END |
| Opening Pressure Setting | 70.0 POUNDS PER SQUARE INCH LBS |
| Valve Discharge Flow Rate | 133.0 CUBIC FEET 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 |
|---|---|
| 304-065 | 3/9 Design control — primary reference Vianney Industries, Llc Dba Midland Metal Manufacturing Company |
NSN 4820-01-491-9965 is a Valve,safety Relief, classified under FSC 4820, Valves, Nonpowered. Status: active.
1 possible match (shared part number, not a government interchangeability claim): 5895-01-599-1595. Verify interchangeability with system specifications before substitution.
Key specifications for 4820-01-491-9965: Flow Control Device: POPPET; Connection Style: PLAIN (SCREW-IN CARTRIDGE) FIRST END; Connection Type: THREADED INTERNAL PIPE FIRST END; Style Designator: SCREW-IN CARTRIDGE. 15 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.