The Valve,safety Relief, cataloged under National Stock Number 4820-01-256-8744, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. The manufacturer of record is Naval Inventory Control Point Mechanicsburg. Government technical data includes 17 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through both NSN and commercial part number lookups. 4 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. 2 items share a part number with this NSN in the catalog (possible match — not a government interchangeability claim). Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4820-01-256-8744 |
| Primary Part Number | D841-4050CP |
| Item Name | Valve,safety Relief |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Manufacturer | Naval Inventory Control Point Mechanicsburg |
| Status | ACTIVE |
| Flow Control Device | DISK |
| Criticality Code Justification | ZZZY |
| Style Designator | ANGLE |
| Material Document and Classification | ASTM B61 ASSN STD SINGLE MATERIAL RESPONSE BODY |
| Material Document and Classification | QQ-N-281 FED SPEC SINGLE MATERIAL RESPONSE FLOW CONTROL DEVICE |
| Material Document and Classification | QQ-N-281 FED SPEC SINGLE MATERIAL RESPONSE STEM |
| Material Document and Classification | QQ-N-281 FED SPEC SINGLE MATERIAL RESPONSE SEAT |
| Operating Pressure | 400.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS |
| Disk Loading Method | SPRING |
| Media for Which Designed | OXYGEN, LIQUID SINGLE RESPONSE |
| Material | NICKEL ALLOY 400 SEAT |
| Material | COPPER ALLOY 922 BODY |
| Material | NICKEL ALLOY 400 STEM |
| Material | NICKEL ALLOY 400 FLOW CONTROL DEVICE |
| Opening Pressure Setting | 80.0 POUNDS PER SQUARE INCH LBS |
| Valve Discharge Flow Rate | 128.0 CUBIC FEET PER MINUTE |
| Reference Number Differentiating Characteristics | CLEANING, PACKAGING, AND MARKING IAW THE LATEST REVISION OF MIL-STD-1330 |
| Acquisition Status | ACTIVE |
| DEMIL Code | DEMIL A — No Demilitarization Required |
| Hazard | No hazard code in the DLA record (HMIC N) |
| Criticality Code | S |
| Part Number | Manufacturer |
|---|---|
| D841-4050CP | Naval Inventory Control Point Mechanicsburg (USA) |
| UU-1551-T | Emerson Automation Solutions Final Control Us Lp Div Navy Product Team (USA) |
| Reference | Meaning |
|---|---|
| UU-1551-TCP | 3/1 Design control — primary reference Naval Inventory Control Point Mechanicsburg |
| D841-4050 | 5/1 Secondary reference U.S. Government activity |
| UU-1551-T | 5/9 Secondary reference Anderson Greenwood Lp Dba Anderson Greenwood Crosby |
| 9955.K 5IM,TYPE | C/1 Advisory reference — outside the item-of-supply concept U.S. Government activity |
NSN 4820-01-256-8744 is a Valve,safety Relief, manufactured by Naval Inventory Control Point Mechanicsburg, classified under FSC 4820, Valves, Nonpowered. Status: active.
NSN 4820-01-256-8744 has 2 manufacturer part numbers on file: D841-4050CP (Naval Inventory Control Point Mechanicsburg), UU-1551-T (Emerson Automation Solutions Final Control Us Lp Div Navy Product Team).
2 possible matches (shared part number, not a government interchangeability claim): 4820-01-330-9426, 4820-01-350-1558. Verify interchangeability with system specifications before substitution.
Key specifications for D841-4050CP: Flow Control Device: DISK; Criticality Code Justification: ZZZY; Style Designator: ANGLE; Material Document and Classification: ASTM B61 ASSN STD SINGLE MATERIAL RESPONSE BODY. 17 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.