The Valve,safety Relief, cataloged under National Stock Number 4820-00-137-1835, 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 25 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through both NSN and commercial part number lookups. 1 additional reference document (drawings, advisory and superseded references) is recorded in the U.S. Government catalog.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 | 4820-00-137-1835 |
| Primary Part Number | 631B-2-3/4-1 |
| 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 |
| Nominal Pipe Size Accommodated | 0.750 INCHES SECOND END IN |
| Nominal Pipe Size Accommodated | 0.750 INCHES FIRST END IN |
| Connection Style | PLAIN,OPTIONAL END(PIPE) FIRST END |
| Connection Style | PLAIN (PIPE) SECOND END |
| Style Designator | ANGLE |
| Material Document and Classification | FEDSTD66,AISI303/SAE30303 FED STD SINGLE MATERIAL RESPONSE FLOW CONTROL DEVICE |
| Operating Pressure | 50.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS |
| Adjustable Pressure Range | +10.0 TO 50.0 POUNDS PER SQUARE INCH LBS |
| Bonnet Type | INSIDE SPRING |
| Thread Direction | RIGHT-HAND SECOND END |
| Thread Direction | RIGHT-HAND FIRST END |
| Nominal Thread Size | 0.750 INCHES SECOND END IN |
| Nominal Thread Size | 0.750 INCHES FIRST END IN |
| Maximum Operating Temp | 225.0 FAHRENHEIT SINGLE RESPONSE DEGF |
| Disk Loading Method | SPRING |
| Bonnet Attachment Method | THREADED |
| Media for Which Designed | WATER-OIL-GAS SINGLE RESPONSE |
| Material | COPPER ALLOY BODY |
| Material | STEEL COMP 303 FLOW CONTROL DEVICE |
| Material | COPPER ALLOY SEAT |
| Thread Series Designator | ANPT FIRST END |
| Thread Series Designator | ANPT SECOND END |
| Opening Pressure Setting | 35.0 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 |
|---|---|
| 631B-2-3/4-1 PRIMARY | Parker-Hannifin Corporation Dba Pneutronics Div Hydraulic Valve Division (USA) |
| Reference | Meaning |
|---|---|
| 631B2-3/4-1 | 5/9 Secondary reference U.S. Government activity |
NSN 4820-00-137-1835 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 4820-00-137-1835 has 1 manufacturer part number on file: 631B-2-3/4-1 (Parker-Hannifin Corporation Dba Pneutronics Div Hydraulic Valve Division).
Key specifications for 631B-2-3/4-1: Flow Control Device: POPPET; Nominal Pipe Size Accommodated: 0.750 INCHES SECOND END IN; Nominal Pipe Size Accommodated: 0.750 INCHES FIRST END IN; Connection Style: PLAIN,OPTIONAL END(PIPE) FIRST END. 25 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.