The Valve,check, cataloged under National Stock Number 4820-00-177-5976, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. The manufacturer of record is Tactair Fluid Controls Inc. Government technical data includes 25 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through both NSN and commercial part number lookups. 3 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. 2 items share a part number with this NSN in the catalog (possible match — not a government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 | 4820-00-177-5976 |
| Primary Part Number | 2656-4 |
| Item Name | Valve,check |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Manufacturer | Tactair Fluid Controls Inc |
| Status | ACTIVE |
| Flow Control Device | POPPET |
| Surface Treatment Document and Classification | QQ-P-35 FED SPEC SINGLE TREATMENT RESPONSE |
| Connection Style | FLARELESS ALL ENDS |
| Mounting Position | HORIZONTAL OR VERTICAL |
| Connection Type | THREADED EXTERNAL TUBE ALL ENDS |
| Style Designator | STRAIGHT THRU |
| Material Document and Classification | 66,AISI 440A/SAE 51440A FED STD SINGLE MATERIAL RESPONSE FLOW CONTROL DEVICE A |
| Material Document and Classification | AMS 5643,TY 630 ASSN STD SINGLE MATERIAL RESPONSE BODY |
| Material Document and Classification | AMS 5643,TY 630 ASSN STD SINGLE MATERIAL RESPONSE SEAT |
| Operating Pressure | 3000.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS |
| Thread Direction | RIGHT-HAND ALL ENDS |
| Nominal Thread Size | 0.438 INCHES ALL ENDS IN |
| Seat Angle | 12.0 DEGREES ALL ENDS |
| Maximum Operating Temp | 275.0 FAHRENHEIT SINGLE RESPONSE DEGF |
| Disk Loading Method | SPRING |
| Surface Treatment | PASSIVATE |
| Media for Which Designed | OIL, HYDRAULIC SINGLE RESPONSE |
| Thread Class | 3A ALL ENDS A |
| Material | STEEL COMP 440A OR STEEL CORROSION RESISTING FLOW CONTROL DEVICE A |
| Material | STEEL CORROSION RESISTING SEAT |
| Material | STEEL CORROSION RESISTING BODY LINING |
| Material | STEEL CORROSION RESISTING BODY |
| Thread Series Designator | UNIFIED NATIONAL JOINT FINE (UNJF) ALL ENDS |
| Opening Pressure Setting | 5.0 POUNDS PER SQUARE INCH LBS |
| Valve Operation Method | AUTOMATIC |
| 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 |
|---|---|
| 2656-4 PRIMARY | Tactair Fluid Controls Inc (USA) |
| Reference | Meaning |
|---|---|
| CVC4124-4 | 5/9 Secondary reference U.S. Government activity |
| 2656-4 | 5/9 Secondary reference U.S. Government activity |
| 2656-4 | 5/9 Secondary reference U.S. Government activity |
NSN 4820-00-177-5976 is a Valve,check, manufactured by Tactair Fluid Controls Inc, classified under FSC 4820, Valves, Nonpowered. Status: active.
NSN 4820-00-177-5976 has 1 manufacturer part number on file: 2656-4 (Tactair Fluid Controls Inc).
2 possible matches (shared part number, not a government interchangeability claim): 5310-00-530-9906, 5340-01-458-8987. Verify interchangeability with system specifications before substitution.
Key specifications for 2656-4: Flow Control Device: POPPET; Surface Treatment Document and Classification: QQ-P-35 FED SPEC SINGLE TREATMENT RESPONSE; Connection Style: FLARELESS ALL ENDS; Mounting Position: HORIZONTAL OR VERTICAL. 25 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.