The Valve,safety Relief, cataloged under National Stock Number 4820-01-183-2261, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. The manufacturer of record is Parker-Hannifin Corporation Dba Pneutronics Div Hydraulic Valve Division. Government technical data includes 16 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through both NSN and commercial part number lookups. 1 additional reference document (drawings, advisory and superseded references) is recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4820-01-183-2261 |
| Primary Part Number | 644XB-1-12-28 |
| Item Name | Valve,safety Relief |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Manufacturer | Parker-Hannifin Corporation Dba Pneutronics Div Hydraulic Valve Division |
| Status | ACTIVE |
| Flow Control Device | POPPET |
| Operating Pressure | 3600.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS |
| Adjustable Pressure Range | +4.0 TO 15.0 POUNDS PER SQUARE INCH LBS |
| Bonnet Type | INSIDE SPRING |
| Thread Direction | RIGHT-HAND FIRST END |
| Nominal Thread Size | 1.062 INCHES FIRST END IN |
| Seat Angle | 37.0 DEGREES FIRST END |
| Disk Loading Method | SPRING |
| Bonnet Attachment Method | INTEGRAL |
| Thread Class | 3A FIRST END A |
| Thread Quantity Per Inch | 12 FIRST END |
| Material | STEEL BODY |
| Material | STEEL FLOW CONTROL DEVICE |
| Material | RUBBER SEAT |
| Thread Series Designator | UN FIRST END |
| Valve Operation Method | AUTOMATIC |
| 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 |
|---|---|
| 644XB-1-12-28 PRIMARY | Parker-Hannifin Corporation Dba Pneutronics Div Hydraulic Valve Division (USA) |
| Reference | Meaning |
|---|---|
| 644XB-1-12-28 | 5/9 Secondary reference U.S. Government activity |
NSN 4820-01-183-2261 is a Valve,safety Relief, manufactured by Parker-Hannifin Corporation Dba Pneutronics Div Hydraulic Valve Division, classified under FSC 4820, Valves, Nonpowered. Status: active.
NSN 4820-01-183-2261 has 1 manufacturer part number on file: 644XB-1-12-28 (Parker-Hannifin Corporation Dba Pneutronics Div Hydraulic Valve Division).
Key specifications for 644XB-1-12-28: Flow Control Device: POPPET; Operating Pressure: 3600.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS; Adjustable Pressure Range: +4.0 TO 15.0 POUNDS PER SQUARE INCH LBS; Bonnet Type: INSIDE SPRING. 16 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.