The Valve,safety Relief, cataloged under National Stock Number 4820-01-283-9425, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. The manufacturer of record is Emerson Automation Solutions Final Control Us Lp Div Navy Product Team. Government technical data includes 30 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through both NSN and commercial part number lookups. 6 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. 2 items share a part number with this NSN in the catalog (possible match — not a government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 | 4820-01-283-9425 |
| Primary Part Number | NMP-1521 OPT 1 1 |
| Item Name | Valve,safety Relief |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Manufacturer | Emerson Automation Solutions Final Control Us Lp Div Navy Product Team |
| Status | ACTIVE |
| Flow Control Device | DISK |
| Flange Shape | ROUND WITH HOLES ALL ENDS |
| Flange Face Design | RAISED STRAIGHT ALL ENDS |
| Bolt Circle Nominal Diameter | 3.125 INCHES FIRST END IN |
| Bolt Circle Nominal Diameter | 2.375 INCHES SECOND END IN |
| Connection Type | FLANGE ALL ENDS |
| Style Designator | ANGLE FLANGED ENDS |
| Bolt Hole Nominal Diameter | 0.625 INCHES SECOND END IN |
| Bolt Hole Nominal Diameter | 0.500 INCHES FIRST END IN |
| Valve Size | 0.500 INCHES IN |
| Adjustable Pressure Range | +156.0 TO 186.0 POUNDS PER SQUARE INCH LBS |
| Bonnet Type | INSIDE SPRING |
| Second Connection Face to Centerline Distance | 3.250 INCHES IN |
| Nominal Outside Diameter | 3.500 INCHES SECOND END IN |
| Nominal Outside Diameter | 4.250 INCHES FIRST END IN |
| Disk Loading Method | SPRING |
| Bolt Hole Quantity | 4 ALL ENDS |
| Bonnet Attachment Method | UNION |
| First Connection Face to Centerline Distance | 3.312 INCHES IN |
| Material | STEEL BODY |
| Material | STEEL CORROSION RESISTING FLOW CONTROL DEVICE |
| Material | STEEL CORROSION RESISTING SEAT |
| Material | STEEL CORROSION RESISTING STEM |
| Raised Face Nominal Diameter | 1.375 INCHES SECOND END IN |
| Raised Face Nominal Diameter | 2.000 INCHES FIRST END IN |
| Valve Operation Method | AUTOMATIC |
| Raised Face Nominal Height | 0.062 INCHES FIRST END IN |
| Raised Face Nominal Height | 0.250 INCHES SECOND END IN |
| Nominal Thickness | 0.438 INCHES SECOND END IN |
| Nominal Thickness | 0.562 INCHES FIRST END IN |
| 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 |
|---|---|
| NMP-1521 OPT 1 1 PRIMARY | Emerson Automation Solutions Final Control Us Lp Div Navy Product Team (USA) |
| DX-10C 156T186PS | Emerson Automation Solutions Final Control Us Lp Div Navy Product Team (USA) |
| Reference | Meaning |
|---|---|
| DX-10C 156T186PSI | 5/9 Secondary reference Anderson Greenwood Lp Dba Anderson Greenwood Crosby |
| NMP-1521 | 5/9 Secondary reference Kunkle Industries Inc Lonergan Valve Div |
| DX-10C 156T186PSI | 5/9 Secondary reference Kunkle Industries Inc Lonergan Valve Div |
| NMP-1521 | D/9 Drawing number reference only Anderson Greenwood Lp Dba Anderson Greenwood Crosby |
| NMP-1521 OPT 1 156T186PSI | 5/9 Secondary reference Anderson Greenwood Lp Dba Anderson Greenwood Crosby |
| NMP-1521 OPT 1 156T186PSI | 5/9 Secondary reference Kunkle Industries Inc Lonergan Valve Div |
NSN 4820-01-283-9425 is a Valve,safety Relief, manufactured by Emerson Automation Solutions Final Control Us Lp Div Navy Product Team, classified under FSC 4820, Valves, Nonpowered. Status: active.
NSN 4820-01-283-9425 has 2 manufacturer part numbers on file: NMP-1521 OPT 1 1 (Emerson Automation Solutions Final Control Us Lp Div Navy Product Team), DX-10C 156T186PS (Emerson Automation Solutions Final Control Us Lp Div Navy Product Team).
2 possible matches (shared part number, not a government interchangeability claim): 4820-01-394-6226, 4820-01-395-0468. Verify interchangeability with system specifications before substitution.
Key specifications for NMP-1521 OPT 1 1: Flow Control Device: DISK; Flange Shape: ROUND WITH HOLES ALL ENDS; Flange Face Design: RAISED STRAIGHT ALL ENDS; Bolt Circle Nominal Diameter: 3.125 INCHES FIRST END IN. 30 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.