The Valve,safety Relief, cataloged under National Stock Number 4820-01-505-8743, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. The manufacturer of record is Naval Sea Systems Command. Government technical data includes 19 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through both NSN and commercial part number lookups. 2 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. 1 item shares a part number with this NSN in the catalog (possible match — not a government interchangeability claim). Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4820-01-505-8743 |
| Primary Part Number | 7326559 FIND 20 |
| Item Name | Valve,safety Relief |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Manufacturer | Naval Sea Systems Command |
| Status | ACTIVE |
| Flow Control Device | POPPET |
| Connection Style | PLAIN (PIPE) FIRST END |
| Connection Type | THREADED EXTERNAL PIPE FIRST END |
| Style Designator | STRAIGHT THRU |
| Operating Pressure | 200.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS |
| Adjustable Pressure Range | +0.5 TO 150.0 POUNDS PER SQUARE INCH LBS |
| Thread Direction | RIGHT-HAND FIRST END |
| Nominal Thread Size | 0.250 INCHES FIRST END IN |
| Maximum Operating Temp | 250.0 FAHRENHEIT SINGLE RESPONSE DEGF |
| Media for Which Designed | ACETYLENE SECOND RESPONSE |
| Media for Which Designed | HYDROGEN FIFTH RESPONSE |
| Media for Which Designed | AMMONIA, GASEOUS THIRD RESPONSE |
| Media for Which Designed | AIR FIRST RESPONSE |
| Media for Which Designed | REFRIGERANT 12 FOURTH RESPONSE |
| Material | RUBBER BUTADIENE-ACRYLONITRILE CLASS NBR SEAT |
| Material | STEEL COMP 303 BODY |
| Thread Series Designator | NPT ALL ENDS |
| Opening Pressure Setting | 12.0 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 |
|---|---|
| 7326559 FIND 20 | Naval Sea Systems Command (USA) |
| Reference | Meaning |
|---|---|
| 559T-2M-12 | 3/2 Design control — primary reference U.S. Government activity |
| 7326559 | D/9 Drawing number reference only Naval Sea Systems Command |
NSN 4820-01-505-8743 is a Valve,safety Relief, manufactured by Naval Sea Systems Command, classified under FSC 4820, Valves, Nonpowered. Status: active.
NSN 4820-01-505-8743 has 1 manufacturer part number on file: 7326559 FIND 20 (Naval Sea Systems Command).
1 possible match (shared part number, not a government interchangeability claim): 4820-01-505-8793. Verify interchangeability with system specifications before substitution.
Key specifications for 7326559 FIND 20: Flow Control Device: POPPET; Connection Style: PLAIN (PIPE) FIRST END; Connection Type: THREADED EXTERNAL PIPE FIRST END; Style Designator: STRAIGHT THRU. 19 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.