The Valve,safety Relief, cataloged under National Stock Number 4820-00-127-8991, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. The manufacturer of record is General Motors Llc Dba General Motors Llc. Government technical data includes 9 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through both NSN and commercial part number lookups. 2 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4820-00-127-8991 |
| Primary Part Number | 665643 |
| Item Name | Valve,safety Relief |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Manufacturer | General Motors Llc Dba General Motors Llc |
| Status | ACTIVE |
| Flow Control Device | DIAPHRAGM |
| Connection Style | PLAIN (PIPE) FIRST END |
| Style Designator | STRAIGHT THRU |
| Thread Direction | RIGHT-HAND FIRST END |
| Nominal Thread Size | 0.250 INCHES FIRST END IN |
| Material | RUBBER SYNTHETIC FLOW CONTROL DEVICE |
| Material | ALUMINUM ALLOY BODY |
| Thread Series Designator | NPT 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 |
| Part Number | Manufacturer |
|---|---|
| 665643 | General Motors Llc Dba General Motors Llc (USA) |
| Reference | Meaning |
|---|---|
| 665643 | 3/9 Design control — primary reference Military Vehicles Opn General Motors Truck and Bus Group Ms 2603-02 |
| 671114 | 5/9 Secondary reference Military Vehicles Opn General Motors Truck and Bus Group Ms 2603-02 |
NSN 4820-00-127-8991 is a Valve,safety Relief, manufactured by General Motors Llc Dba General Motors Llc, classified under FSC 4820, Valves, Nonpowered. Status: active.
NSN 4820-00-127-8991 has 1 manufacturer part number on file: 665643 (General Motors Llc Dba General Motors Llc).
Key specifications for 665643: Flow Control Device: DIAPHRAGM; Connection Style: PLAIN (PIPE) FIRST END; Style Designator: STRAIGHT THRU; Thread Direction: RIGHT-HAND FIRST END. 9 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.