The Piston,valve, cataloged under National Stock Number 4820-01-189-3284, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. Government technical data includes 6 specifications, cited from the U.S. Government catalog. 3 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. 3 items share a part number with this NSN in the catalog (possible match — not a government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 | 4820-01-189-3284 |
| Item Name | Piston,valve |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Status | ACTIVE |
| Valve Type for Which Designed | PRESSURE REDUCING |
| Valve Model Number for Which Designed | NAP895 |
| Material Document and Classification | MIL-S-862 MIL SPEC SINGLE MATERIAL RESPONSE |
| Valve Size for Which Designed | 2.000 INCHES IN |
| Valve Design Control Activity | 70667 |
| Material | STEEL CORROSION RESISTING |
| 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 |
|---|---|
| NAP895 | D/9 Drawing number reference only Atlas Valve Co |
| P563E | 3/9 Design control — primary reference Atlas Valve Co |
| NAP895 PIECE 12 | 5/9 Secondary reference Atlas Valve Co |
NSN 4820-01-189-3284 is a Piston,valve, classified under FSC 4820, Valves, Nonpowered. Status: active.
3 possible matches (shared part number, not a government interchangeability claim): 4820-01-189-8673, 4820-01-190-7098, 4820-01-290-7376. Verify interchangeability with system specifications before substitution.
Key specifications for 4820-01-189-3284: Valve Type for Which Designed: PRESSURE REDUCING; Valve Model Number for Which Designed: NAP895; Material Document and Classification: MIL-S-862 MIL SPEC SINGLE MATERIAL RESPONSE; Valve Size for Which Designed: 2.000 INCHES 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.