The Seat,valve, cataloged under National Stock Number 4820-01-204-8418, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. Government technical data includes 8 specifications, cited from the U.S. Government catalog. 5 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. 1 item shares a part number with this NSN in the catalog (possible match — not a government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 | 4820-01-204-8418 |
| Item Name | Seat,valve |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Status | ACTIVE |
| Flange Seat to Disk End Height | 0.187 INCHES NOMINAL IN |
| Flange Diameter | 3.187 INCHES NOMINAL IN |
| Style Designator | THREADED FLANGED |
| Body Inside Diameter | 2.500 INCHES NOMINAL IN |
| Under Flange Height | 0.531 INCHES NOMINAL IN |
| Material | NICKEL ALLOY SEAT |
| Seat Angle in Deg | 45.000 NOMINAL |
| Seating Surface Shape | ANGULAR |
| 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 |
|---|---|
| 2620-922X2 ASSEMBLY GS PIECE 31 | 5/2 Secondary reference U.S. Government activity |
| 1889553 PIECE 31 | 5/2 Secondary reference U.S. Government activity |
| 1889553 | D/9 Drawing number reference only U.S. Government activity |
| 7874-94 | 3/2 Design control — primary reference U.S. Government activity |
| 2620-922X2 | D/9 Drawing number reference only U.S. Government activity |
NSN 4820-01-204-8418 is a Seat,valve, classified under FSC 4820, Valves, Nonpowered. Status: active.
1 possible match (shared part number, not a government interchangeability claim): 4820-01-209-4588. Verify interchangeability with system specifications before substitution.
Key specifications for 4820-01-204-8418: Flange Seat to Disk End Height: 0.187 INCHES NOMINAL IN; Flange Diameter: 3.187 INCHES NOMINAL IN; Style Designator: THREADED FLANGED; Body Inside Diameter: 2.500 INCHES NOMINAL IN. 8 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.