The Seat,valve, cataloged under National Stock Number 4820-00-413-4261, 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 14 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 items share a part number with this NSN in the catalog (possible match — not a government interchangeability claim). Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4820-00-413-4261 |
| Primary Part Number | 79557 |
| Item Name | Seat,valve |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Manufacturer | Ashcroft Inc Dba Heise |
| Status | ACTIVE |
| Thread Length | 0.375 INCHES NOMINAL SECOND THREADED PORTION IN |
| Thread Length | 0.935 INCHES NOMINAL FIRST THREADED PORTION IN |
| Style Designator | DOUBLE FLANGED |
| Body Inside Diameter | 1.880 INCHES NOMINAL IN |
| Nominal Thread Size | 2.625 INCHES FIRST THREADED PORTION IN |
| Nominal Thread Size | 2.812 INCHES SECOND THREADED PORTION IN |
| Thread Class | 2A FIRST THREADED PORTION A |
| Thread Quantity Per Inch | 16 FIRST THREADED PORTION |
| Thread Quantity Per Inch | 18 SECOND THREADED PORTION |
| Material | STEEL OVERALL |
| Seat Angle in Deg | 45.000 NOMINAL |
| Thread Series Designator | UN FIRST THREADED PORTION |
| Thread Series Designator | UNS SECOND THREADED PORTION |
| 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 |
| Part Number | Manufacturer |
|---|---|
| 79557 PRIMARY | Ashcroft Inc Dba Heise (USA) |
NSN 4820-00-413-4261 is a Seat,valve, manufactured by Ashcroft Inc Dba Heise, classified under FSC 4820, Valves, Nonpowered. Status: active.
NSN 4820-00-413-4261 has 1 manufacturer part number on file: 79557 (Ashcroft Inc Dba Heise).
2 possible matches (shared part number, not a government interchangeability claim): 5330-01-478-7866, 5330-01-656-5513. Verify interchangeability with system specifications before substitution.
Key specifications for 79557: Overall Height: 2.910 INCHES NOMINAL IN; Thread Length: 0.375 INCHES NOMINAL SECOND THREADED PORTION IN; Thread Length: 0.935 INCHES NOMINAL FIRST THREADED PORTION IN; Style Designator: DOUBLE FLANGED. 14 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.