The Valve,safety Relief, cataloged under National Stock Number 4820-00-552-3498, 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 2 manufacturer part numbers 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through both NSN and commercial part number lookups. 1 additional reference document (drawings, advisory and superseded references) is recorded in the U.S. Government catalog.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 | 4820-00-552-3498 |
| Primary Part Number | 645B-6-12-T |
| 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 | 0.750 INCHES ALL ENDS IN |
| Operating Pressure | 3100.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS |
| Adjustable Pressure Range | +430.0 TO 650.0 POUNDS PER SQUARE INCH LBS |
| Features Provided | PRESSURE TIGHT OUTLET SIDE |
| Thread Direction | RIGHT-HAND ALL ENDS |
| Nominal Thread Size | 1.062 INCHES ALL ENDS IN |
| Maximum Operating Temp | 400.0 FAHRENHEIT SINGLE RESPONSE DEGF |
| Disk Loading Method | SPRING |
| Surface Treatment | PASSIVATE LOCATION NOT OTHERWISE SPECIFIED |
| Media for Which Designed | WATER-OIL-GAS SINGLE RESPONSE |
| Thread Class | 3B ALL ENDS |
| Thread Quantity Per Inch | 12 ALL ENDS |
| Material | STEEL COMP 303 SEAT |
| Material | STEEL COMP 303 BODY |
| Material | STEEL COMP 303 AND PLASTIC POLYTETRAFLUOROETHYLENE FLOW CONTROL DEVICE |
| Thread Series Designator | UNIFIED NATIONAL JOINT (UNJ) ALL ENDS |
| Opening Pressure Setting | 550.0 POUNDS PER SQUARE INCH LBS |
| Valve Operation Method | AUTOMATIC |
| Acquisition Status | ACTIVE |
| DEMIL Code | DEMIL Q — CCL Item — Commerce Control List |
| Hazard | No hazard code in the DLA record (HMIC N) |
| Criticality Code | X |
| Part Number | Manufacturer |
|---|---|
| 645B-6-12-T PRIMARY | Parker-Hannifin Corporation Dba Pneutronics Div Hydraulic Valve Division (USA) |
| 645B-6-12-T | United Dynamics, Inc (USA) |
| Reference | Meaning |
|---|---|
| 645B6-12T | 5/9 Secondary reference U.S. Government activity |
NSN 4820-00-552-3498 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 4820-00-552-3498 has 2 manufacturer part numbers on file: 645B-6-12-T (Parker-Hannifin Corporation Dba Pneutronics Div Hydraulic Valve Division), 645B-6-12-T (United Dynamics, Inc).
Key specifications for 645B-6-12-T: 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.
NSN 4820-00-552-3498 has DEMIL Code Q. Demilitarization may be required before disposal or transfer to non-military entities.
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.