The Valve,safety Relief, cataloged under National Stock Number 4820-01-418-9539, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. Government technical data includes 18 specifications, cited from the U.S. Government catalog. 3 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4820-01-418-9539 |
| Item Name | Valve,safety Relief |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Status | ACTIVE |
| Flow Control Device | POPPET |
| Connection Style | FLARED (TUBE) FIRST END |
| Minimum Operating Temp | -70.0 FAHRENHEIT DEGF |
| Connection Type | THREADED EXTERNAL TUBE FIRST END |
| Style Designator | STRAIGHT THRU W/BAFFLE |
| Operating Pressure | 115.5 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS |
| Adjustable Pressure Range | +99.8 TO 110.3 POUNDS PER SQUARE INCH LBS |
| Thread Direction | RIGHT-HAND FIRST END |
| Nominal Thread Size | 0.438 INCHES FIRST END IN |
| Seat Angle | 37.0 DEGREES FIRST END |
| Maximum Operating Temp | 260.0 FAHRENHEIT SINGLE RESPONSE DEGF |
| Media for Which Designed | AIR FIRST RESPONSE |
| Media for Which Designed | WATER, FRESH SECOND RESPONSE |
| Thread Class | 3A FIRST END A |
| Material | STEEL COMP 303 FLOW CONTROL DEVICE |
| Material | STEEL COMP 303 BODY |
| Thread Series Designator | UNIFIED NATIONAL JOINT FINE (UNJF) FIRST END |
| 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 |
|---|---|
| ES9998-04 | 5/2 Secondary reference U.S. Government activity |
| ES9998-04 | 5/9 Secondary reference Drs Sustainment Systems, Inc. |
| RV05-424 | 3/2 Design control — primary reference U.S. Government activity |
NSN 4820-01-418-9539 is a Valve,safety Relief, classified under FSC 4820, Valves, Nonpowered. Status: active.
Key specifications for 4820-01-418-9539: Flow Control Device: POPPET; Connection Style: FLARED (TUBE) FIRST END; Minimum Operating Temp: -70.0 FAHRENHEIT DEGF; Connection Type: THREADED EXTERNAL TUBE FIRST END. 18 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.