The Valve,butterfly, cataloged under National Stock Number 4820-00-401-0256, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. The manufacturer of record is Oshkosh Defense Llc. Government technical data includes 4 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through both NSN and commercial part number lookups. 2 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog.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 | 4820-00-401-0256 |
| Primary Part Number | 1639840U |
| Item Name | Valve,butterfly |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Manufacturer | Oshkosh Defense Llc |
| Status | ACTIVE |
| Style Designator | STRAIGHT THRU |
| Material | STEEL CORROSION RESISTING BODY |
| Material | RUBBER SYNTHETIC SEAT |
| Valve Operation Method | MANUAL |
| 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 |
|---|---|
| 1639840U PRIMARY | Oshkosh Defense Llc (USA) |
| Reference | Meaning |
|---|---|
| 31997CX | 3/9 Design control — primary reference Oshkosh Corp |
| 1639840U | 5/9 Secondary reference Oshkosh Corp |
NSN 4820-00-401-0256 is a Valve,butterfly, manufactured by Oshkosh Defense Llc, classified under FSC 4820, Valves, Nonpowered. Status: active.
NSN 4820-00-401-0256 has 1 manufacturer part number on file: 1639840U (Oshkosh Defense Llc).
Key specifications for 1639840U: Style Designator: STRAIGHT THRU; Material: STEEL CORROSION RESISTING BODY; Material: RUBBER SYNTHETIC SEAT; Valve Operation Method: MANUAL. 4 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.