The Valve,safety Relief, cataloged under National Stock Number 4820-00-451-0646, 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 22 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through both NSN and commercial part number lookups. 2 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4820-00-451-0646 |
| Primary Part Number | 625B-4-4-27 |
| 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 |
| Connection Style | GASKET SEAL(BOSS) ALL ENDS |
| Connection Type | THREADED INTERNAL BOSS ALL ENDS |
| Style Designator | ANGLE |
| Nominal Outside Diameter Tube Accommodated | 0.250 INCHES ALL ENDS IN |
| Operating Pressure | 3100.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS |
| Adjustable Pressure Range | +115.0 TO 250.0 POUNDS PER SQUARE INCH LBS |
| Features Provided | BONNET PACKING AND PRESSURE TIGHT OUTLET SIDE |
| Bonnet Type | INSIDE SPRING |
| Thread Direction | RIGHT-HAND ALL ENDS |
| Nominal Thread Size | 0.437 INCHES ALL ENDS IN |
| Maximum Operating Temp | 180.0 FAHRENHEIT SINGLE RESPONSE DEGF |
| Disk Loading Method | SPRING |
| Surface Treatment | ANODIZE LOCATION NOT OTHERWISE SPECIFIED |
| Bonnet Attachment Method | THREADED |
| Media for Which Designed | OIL, HYDRAULIC SECOND RESPONSE |
| Media for Which Designed | HYDRAULIC FLUID, MINERAL BASE FIRST RESPONSE |
| Thread Class | 3B ALL ENDS |
| Material | ALUMINUM ALLOY OVERALL |
| Thread Series Designator | UNIFIED NATIONAL JOINT FINE (UNJF) ALL ENDS |
| Opening Pressure Setting | 200.0 POUNDS PER SQUARE INCH LBS |
| 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 |
|---|---|
| 625B-4-4-27 PRIMARY | Parker-Hannifin Corporation Dba Pneutronics Div Hydraulic Valve Division (USA) |
| Reference | Meaning |
|---|---|
| 625B4-4-3 | 5/9 Secondary reference U.S. Government activity |
| 625B4-4-27 | 5/9 Secondary reference U.S. Government activity |
NSN 4820-00-451-0646 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 4820-00-451-0646 has 1 manufacturer part number on file: 625B-4-4-27 (Parker-Hannifin Corporation Dba Pneutronics Div Hydraulic Valve Division).
Key specifications for 625B-4-4-27: Flow Control Device: POPPET; Connection Style: GASKET SEAL(BOSS) ALL ENDS; Connection Type: THREADED INTERNAL BOSS ALL ENDS; Style Designator: ANGLE. 22 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.