The Valve,safety Relief, cataloged under National Stock Number 4820-01-107-4261, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. The manufacturer of record is Ausco Inc. Government technical data includes 15 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through both NSN and commercial part number lookups. 1 additional reference document (drawings, advisory and superseded references) is recorded in the U.S. Government catalog.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 | 4820-01-107-4261 |
| Primary Part Number | H-993 |
| Item Name | Valve,safety Relief |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Manufacturer | Ausco Inc |
| Status | ACTIVE |
| Flow Control Device | DISK |
| Connection Style | PLAIN (SCREW-IN CARTRIDGE) ALL ENDS |
| Connection Type | THREADED CARTRIDGE ALL ENDS |
| Style Designator | SCREW-IN CARTRIDGE |
| Operating Pressure | 3000.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS |
| Adjustable Pressure Range | +100.0 TO 150.0 POUNDS PER SQUARE INCH LBS |
| Thread Direction | RIGHT-HAND ALL ENDS |
| Nominal Thread Size | 0.562 INCHES ALL ENDS IN |
| Maximum Operating Temp | 275.0 FAHRENHEIT SINGLE RESPONSE DEGF |
| Media for Which Designed | OIL, HYDRAULIC SINGLE RESPONSE |
| Thread Class | 3A ALL ENDS A |
| Material | STEEL CORROSION RESISTING FLOW CONTROL DEVICE |
| Material | STEEL CORROSION RESISTING SEAT |
| Thread Series Designator | UNIFIED NATIONAL JOINT FINE (UNJF) ALL ENDS |
| Valve Operation Method | AUTOMATIC |
| Acquisition Status | ACTIVE |
| DEMIL Code | DEMIL B — Remove Demilitarization Key Points |
| Hazard | No hazard code in the DLA record (HMIC N) |
| Criticality Code | X |
| Part Number | Manufacturer |
|---|---|
| H-993 PRIMARY | Ausco Inc (USA) |
| Reference | Meaning |
|---|---|
| 13025220 | 7/2 Vendor item drawing reference Us Army Aviation and Missile Command |
NSN 4820-01-107-4261 is a Valve,safety Relief, manufactured by Ausco Inc, classified under FSC 4820, Valves, Nonpowered. Status: active.
NSN 4820-01-107-4261 has 1 manufacturer part number on file: H-993 (Ausco Inc).
Key specifications for H-993: Flow Control Device: DISK; Connection Style: PLAIN (SCREW-IN CARTRIDGE) ALL ENDS; Connection Type: THREADED CARTRIDGE ALL ENDS; Style Designator: SCREW-IN CARTRIDGE. 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.
NSN 4820-01-107-4261 has DEMIL Code B. 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.