The Valve,check, cataloged under National Stock Number 4820-01-031-3621, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. The manufacturer of record is Northrop Grumman Systems Corporation. Government technical data includes 21 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through both NSN and commercial part number lookups. 2 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4820-01-031-3621 |
| Primary Part Number | A51P20339-27 |
| Item Name | Valve,check |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Manufacturer | Northrop Grumman Systems Corporation |
| Status | ACTIVE |
| Flow Control Device | DISK |
| Flange Shape | ROUND WITH HOLES THIRD END |
| Flange Face Design | PLAIN THIRD END |
| Connection Style | GROOVED (TUBE) FIRST END |
| Connection Style | GROOVED (TUBE) SECOND END |
| Bolt Circle Nominal Diameter | 4.275 INCHES THIRD END IN |
| Mounting Position | HORIZONTAL OR VERTICAL |
| Connection Type | UNTHREADED EXTERNAL TUBE FIRST END |
| Connection Type | UNTHREADED EXTERNAL TUBE SECOND END |
| Connection Type | FLANGE THIRD END |
| Style Designator | CROSS |
| Bolt Hole Nominal Diameter | 0.282 INCHES THIRD END IN |
| Nominal Outside Diameter Tube Accommodated | 3.500 INCHES FIRST END IN |
| Nominal Outside Diameter Tube Accommodated | 3.500 INCHES SECOND END IN |
| Nominal Outside Diameter | 5.280 INCHES THIRD END IN |
| Disk Loading Method | SPRING |
| Mounting Facility | BRACKET(S) |
| Bolt Hole Quantity | 6 THIRD END |
| Material | ALUMINUM ALLOY OVERALL |
| Valve Operation Method | AUTOMATIC |
| Nominal Thickness | 0.205 INCHES THIRD END IN |
| 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 |
|---|---|
| A51P20339-27 PRIMARY | Northrop Grumman Systems Corporation (USA) |
| Reference | Meaning |
|---|---|
| A51P20339-27 | 3/9 Design control — primary reference Northrop Grumman Systems Corporation Dba Northrop Grumman Systems Corp Div Northrop Grumman Aeronautics Systems |
| A51P20339-27 | 5/9 Secondary reference Northrop Grumman Systems Corporation |
NSN 4820-01-031-3621 is a Valve,check, manufactured by Northrop Grumman Systems Corporation, classified under FSC 4820, Valves, Nonpowered. Status: active.
NSN 4820-01-031-3621 has 1 manufacturer part number on file: A51P20339-27 (Northrop Grumman Systems Corporation).
Key specifications for A51P20339-27: Flow Control Device: DISK; Flange Shape: ROUND WITH HOLES THIRD END; Flange Face Design: PLAIN THIRD END; Connection Style: GROOVED (TUBE) FIRST END. 21 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.