The Valve,safety Relief, cataloged under National Stock Number 4820-00-291-6670, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. The manufacturer of record is Ashcroft Inc Dba Heise. Government technical data includes 26 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through both NSN and commercial part number lookups. 1 additional reference document (drawings, advisory and superseded references) is recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4820-00-291-6670 |
| Primary Part Number | 1478-3-3 |
| Item Name | Valve,safety Relief |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Manufacturer | Ashcroft Inc Dba Heise |
| Status | ACTIVE |
| Flow Control Device | DISK |
| Nominal Pipe Size Accommodated | 3.000 INCHES SECOND END IN |
| Nominal Pipe Size Accommodated | 3.000 INCHES FIRST END IN |
| Connection Style | PLAIN (PIPE) SECOND END |
| Connection Type | THREADED INTERNAL PIPE FIRST END |
| Connection Type | THREADED EXTERNAL PIPE SECOND END |
| Style Designator | ANGLE |
| Operating Pressure | 150.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS |
| Features Provided | BONNET PACKING AND PRESSURE TIGHT OUTLET SIDE |
| Bonnet Type | INSIDE SPRING |
| Thread Direction | RIGHT-HAND SECOND END |
| Thread Direction | RIGHT-HAND FIRST END |
| Nominal Thread Size | 3.000 INCHES SECOND END IN |
| Nominal Thread Size | 3.000 INCHES FIRST END IN |
| Maximum Operating Temp | 406.0 FAHRENHEIT SINGLE RESPONSE DEGF |
| Disk Loading Method | SPRING |
| Bonnet Attachment Method | THREADED |
| Thread Quantity Per Inch | 8 SECOND END |
| Thread Quantity Per Inch | 8 FIRST END |
| Material | COPPER ALLOY BODY |
| Material | COPPER ALLOY SEAT |
| Thread Series Designator | NPT SECOND END |
| Thread Series Designator | NPT FIRST END |
| Opening Pressure Setting | 85.0 POUNDS PER SQUARE INCH LBS |
| Valve Discharge Flow Rate | 297.0 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 |
| Part Number | Manufacturer |
|---|---|
| 1478-3-3 PRIMARY | Ashcroft Inc Dba Heise (USA) |
| Reference | Meaning |
|---|---|
| 342C722H01 | 7/2 Vendor item drawing reference U.S. Government activity |
NSN 4820-00-291-6670 is a Valve,safety Relief, manufactured by Ashcroft Inc Dba Heise, classified under FSC 4820, Valves, Nonpowered. Status: active.
NSN 4820-00-291-6670 has 1 manufacturer part number on file: 1478-3-3 (Ashcroft Inc Dba Heise).
Key specifications for 1478-3-3: Flow Control Device: DISK; Nominal Pipe Size Accommodated: 3.000 INCHES SECOND END IN; Nominal Pipe Size Accommodated: 3.000 INCHES FIRST END IN; Connection Style: PLAIN (PIPE) SECOND END. 26 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.