The Seat,valve, cataloged under National Stock Number 4820-01-524-1901, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. The manufacturer of record is Naval Sea Systems Command. Government technical data includes 6 specifications, cited from the U.S. Government catalog. The record lists 2 manufacturer part numbers 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through both NSN and commercial part number lookups. 2 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. 1 item shares a part number with this NSN in the catalog (possible match — not a government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 | 4820-01-524-1901 |
| Primary Part Number | 506-7503537 2.5IN PART NO 33 |
| Item Name | Seat,valve |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Manufacturer | Naval Sea Systems Command |
| Status | ACTIVE |
| Style Designator | PLAIN THREADED |
| Material Document and Classification | QQ-N-281 CL. A FED SPEC SINGLE MATERIAL RESPONSE SEAT |
| Body Inside Diameter | 2.750 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 |
| Part Number | Manufacturer |
|---|---|
| 506-7503537 2.5IN PART NO 33 PRIMARY | Naval Sea Systems Command (USA) |
| 506-5588322 2.5IN PART NO 20 | Naval Sea Systems Command (USA) |
| Reference | Meaning |
|---|---|
| 5588322 | D/9 Drawing number reference only U.S. Government activity |
| 7503537 | D/9 Drawing number reference only Huntington Ingalls Inc Div Newport News Shipbuilding |
NSN 4820-01-524-1901 is a Seat,valve, manufactured by Naval Sea Systems Command, classified under FSC 4820, Valves, Nonpowered. Status: active.
NSN 4820-01-524-1901 has 2 manufacturer part numbers on file: 506-7503537 2.5IN PART NO 33 (Naval Sea Systems Command), 506-5588322 2.5IN PART NO 20 (Naval Sea Systems Command).
1 possible match (shared part number, not a government interchangeability claim): 4820-01-524-2689. Verify interchangeability with system specifications before substitution.
Key specifications for 506-7503537 2.5IN PART NO 33: Overall Height: 0.500 INCHES NOMINAL IN; Style Designator: PLAIN THREADED; Material Document and Classification: QQ-N-281 CL. A FED SPEC SINGLE MATERIAL RESPONSE SEAT; Body Inside Diameter: 2.750 INCHES NOMINAL IN. 6 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.