The Valve,safety Relief, cataloged under National Stock Number 4820-01-190-0353, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. The manufacturer of record is Teledyne Defense Electronics, Llc Dba Teledyne Relays Div Https://www.teledyne.com/what-We-Do/. Government technical data includes 15 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. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4820-01-190-0353 |
| Primary Part Number | 637B-2-1/4-2 |
| Item Name | Valve,safety Relief |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Manufacturer | Teledyne Defense Electronics, Llc Dba Teledyne Relays Div Https://www.teledyne.com/what-We-Do/ |
| Status | ACTIVE |
| Flow Control Device | DISK |
| Connection Style | PLAIN,OPTIONAL END(PIPE) ALL ENDS |
| Connection Type | THREADED INTERNAL PIPE ALL ENDS |
| Style Designator | ANGLE |
| Operating Pressure | 3100.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS |
| Thread Direction | RIGHT-HAND FIRST END |
| Nominal Thread Size | 0.250 INCHES FIRST END IN |
| Maximum Operating Temp | 225.0 FAHRENHEIT SINGLE RESPONSE DEGF |
| Disk Loading Method | SPRING |
| Media for Which Designed | LIQUID, INGESTED SECOND RESPONSE |
| Media for Which Designed | AIR FIRST RESPONSE |
| Material | COPPER ALLOY BODY |
| Thread Series Designator | NPT FIRST 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 |
|---|---|
| 4706K252 | Mcmaster-Carr Supply Co (USA) |
| 637B-2-1/4-2 PRIMARY | Teledyne Defense Electronics, Llc Dba Teledyne Relays Div Https://www.teledyne.com/what-We-Do/ (USA) |
NSN 4820-01-190-0353 is a Valve,safety Relief, manufactured by Teledyne Defense Electronics, Llc Dba Teledyne Relays Div Https://www.teledyne.com/what-We-Do/, classified under FSC 4820, Valves, Nonpowered. Status: active.
NSN 4820-01-190-0353 has 2 manufacturer part numbers on file: 4706K252 (Mcmaster-Carr Supply Co), 637B-2-1/4-2 (Teledyne Defense Electronics, Llc Dba Teledyne Relays Div Https://www.teledyne.com/what-We-Do/).
Key specifications for 637B-2-1/4-2: Flow Control Device: DISK; Connection Style: PLAIN,OPTIONAL END(PIPE) ALL ENDS; Connection Type: THREADED INTERNAL PIPE ALL ENDS; Style Designator: ANGLE. 15 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.