The Valve,safety Relief, cataloged under National Stock Number 4820-00-220-1850, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. Government technical data includes 29 specifications, cited from the U.S. Government catalog. 3 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4820-00-220-1850 |
| Item Name | Valve,safety Relief |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Status | ACTIVE |
| Flow Control Device | DISK |
| Flange Shape | ROUND WITH HOLES FIRST END |
| Flange Shape | ROUND WITH HOLES SECOND END |
| Renewable Seat Ring Type | THREADED |
| Flange Face Design | RAISED STRAIGHT FIRST END |
| Flange Face Design | PLAIN SECOND END |
| Bolt Circle Nominal Diameter | 5.000 INCHES FIRST END IN |
| Bolt Circle Nominal Diameter | 5.188 INCHES SECOND END IN |
| Connection Type | FLANGE SECOND END |
| Connection Type | FLANGE FIRST END |
| Style Designator | ANGLE |
| Bolt Hole Nominal Diameter | 0.688 INCHES FIRST END IN |
| Bolt Hole Nominal Diameter | 0.688 INCHES SECOND END IN |
| Adjustable Pressure Range | +580.0 TO 630.0 POUNDS PER SQUARE INCH LBS |
| Features Provided | PRESSURE TIGHT OUTLET SIDE |
| Bonnet Type | EXPOSED SPRING |
| Nominal Outside Diameter | 6.500 INCHES FIRST END IN |
| Nominal Outside Diameter | 6.500 INCHES SECOND END IN |
| Disk Loading Method | SPRING |
| Bolt Hole Quantity | 8 FIRST END |
| Bolt Hole Quantity | 7 SECOND END |
| Bonnet Attachment Method | BOLTED |
| Raised Face Nominal Diameter | 3.625 INCHES FIRST END IN |
| Opening Pressure Setting | 624.0 POUNDS PER SQUARE INCH LBS |
| Valve Discharge Flow Rate | 13000.0 POUNDS PER HOUR LBS |
| Raised Face Nominal Height | 0.250 INCHES FIRST END IN |
| Nominal Thickness | 0.750 INCHES SECOND END IN |
| Nominal Thickness | 1.000 INCHES FIRST END IN |
| Reference Number Differentiating Characteristics | AS DIFFERENTIATED BY THE VALVE DISCHARGE FLOW RATE REQUIREMENT |
| Acquisition Status | ACTIVE |
| DEMIL Code | DEMIL A — No Demilitarization Required |
| Hazard | No hazard code in the DLA record (HMIC N) |
| Criticality Code | X |
| Reference | Meaning |
|---|---|
| R6181AZ | 5/9 Secondary reference Dresser, Inc. Dba Dresser Equipment Group Div Industrial Valve Operations, Dresse |
| CL55S51-98 | 5/1 Secondary reference U.S. Government activity |
| R6181AZ | 3/1 Design control — primary reference Ashcroft Inc Dba Heise |
NSN 4820-00-220-1850 is a Valve,safety Relief, classified under FSC 4820, Valves, Nonpowered. Status: active.
Key specifications for 4820-00-220-1850: Flow Control Device: DISK; Flange Shape: ROUND WITH HOLES FIRST END; Flange Shape: ROUND WITH HOLES SECOND END; Renewable Seat Ring Type: THREADED. 29 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.