The Valve,safety Relief, cataloged under National Stock Number 4820-01-221-1578, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. Government technical data includes 30 specifications, cited from the U.S. Government catalog. 5 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. 1 item shares a part number with this NSN in the catalog (possible match — not a government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 | 4820-01-221-1578 |
| Item Name | Valve,safety Relief |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Status | ACTIVE |
| Flow Control Device | DISK |
| Flange Shape | ROUND WITH HOLES ALL ENDS |
| Furnished Items and Quantity | 1 LEVER |
| Flange Face Design | RAISED STRAIGHT ALL ENDS |
| Bolt Circle Nominal Diameter | 3.875 INCHES SECOND END IN |
| Bolt Circle Nominal Diameter | 6.000 INCHES FIRST END IN |
| Connection Type | FLANGE ALL ENDS |
| Style Designator | ANGLE FLANGED ENDS |
| Bolt Hole Nominal Diameter | 0.625 INCHES SECOND END IN |
| Bolt Hole Nominal Diameter | 0.750 INCHES FIRST END IN |
| Operating Pressure | 400.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS |
| Valve Size | 1.500 INCHES IN |
| Adjustable Pressure Range | +8.0 TO 10.0 POUNDS PER SQUARE INCH LBS |
| Bonnet Type | INSIDE SCREW |
| Maximum Operating Temp | 250.0 FAHRENHEIT SINGLE RESPONSE DEGF |
| Second Connection Face to Centerline Distance | 5.680 INCHES IN |
| Nominal Outside Diameter | 5.000 INCHES SECOND END IN |
| Nominal Outside Diameter | 7.500 INCHES FIRST END IN |
| Bolt Hole Quantity | 4 ALL ENDS |
| Bonnet Attachment Method | BOLTED |
| Media for Which Designed | WATER-OIL-GAS SINGLE RESPONSE |
| First Connection Face to Centerline Distance | 5.370 INCHES IN |
| Material | STEEL BODY |
| Material | STEEL COMP 303 STEM |
| Material | STEEL CORROSION RESISTING FLOW CONTROL DEVICE |
| Material | STEEL CORROSION RESISTING SEAT |
| Raised Face Nominal Diameter | 5.000 INCHES FIRST END IN |
| Raised Face Nominal Diameter | 2.875 INCHES SECOND END IN |
| Valve Operation Method | AUTOMATIC |
| Raised Face Nominal Height | 0.062 INCHES ALL ENDS IN |
| 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 |
|---|---|
| R10AH5L502-CS4 | C/1 Advisory reference — outside the item-of-supply concept Hunt Valve Company, Inc. |
| R10AH5L502-CS4 | 3/9 Design control — primary reference Hunt Valve Company Inc Dba Union Flonetics |
| D49695 | 5/9 Secondary reference Hunt Valve Company Inc Dba Union Flonetics |
| D49695 | C/1 Advisory reference — outside the item-of-supply concept Hunt Valve Company, Inc. |
| R10AZ5L502-CS4 | C/1 Advisory reference — outside the item-of-supply concept Hunt Valve Company Inc Dba Union Flonetics |
NSN 4820-01-221-1578 is a Valve,safety Relief, classified under FSC 4820, Valves, Nonpowered. Status: active.
1 possible match (shared part number, not a government interchangeability claim): 4820-01-263-3049. Verify interchangeability with system specifications before substitution.
Key specifications for 4820-01-221-1578: Flow Control Device: DISK; Flange Shape: ROUND WITH HOLES ALL ENDS; Furnished Items and Quantity: 1 LEVER; Flange Face Design: RAISED STRAIGHT ALL ENDS. 30 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.