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639AS1021 — CAP,PROTECTIVE,DUST AND MOISTURE

✓ Government record, cited
— · ORING SEAL
PRODUCT OVERVIEW

639AS1021: CAP,PROTECTIVE,DUST AND MOISTURE.

CAP,PROTECTIVE,DUST AND MOISTURE. Key specifications include material: PLASTIC, POLYETHYLENE (PP), design_type: FRICTION, overall_diameter: 2.180 INCHES NOMINAL IN, opening_inside_diameter_for_which_designed: 2.090 INCHES MINIMUM AND 2.110 INCHES MAXIMUM IN. This part is cataloged in the U.S.

Government catalog under NSN 5340-01-131-0725, indicating validated use in U.S. government and defense logistics supply chains. Available through authorized enterprise resellers and TPM (Third Party Maintenance) channels.

Verify compatibility with your specific system configuration before ordering.

WHERE IT FITS
639AS1021
NSN: 5340-01-131-0725
FSC: 5340 — Hardware, Commercial
CAGE: 30003 — NAVAL AIR SYSTEMS COMMAND MANAGED ORIGINAL DESIGN ACTIVITY NOT MATERIAL/PARTS SUPPLIER (USA)
SPECIFICATIONS
materialPLASTIC, POLYETHYLENE (PP)
design_typeFRICTION
overall_diameter2.180 INCHES NOMINAL IN
opening_inside_diameter_for_which_designed2.090 INCHES MINIMUM AND 2.110 INCHES MAXIMUM IN
NSN5340-01-131-0725
COMPONENT DIAGRAM
O-RING / SEAL — MATERIAL DETERMINES APPLICATION ID: — CROSS-SECTION CS: — SPECIFICATION Material: — Durometer: — Temp: — PN: 639AS1021 MFR: OEM ⚠ VERIFY BEFORE ORDERING Wrong material = failure. Viton for oil/fuel, EPDM for water/steam, Buna-N for general purpose, Silicone for food-grade. Chemical incompatibility causes swelling, brittleness, or rapid degradation ✓ BROKER TIP Durometer (hardness) affects sealing pressure tolerance. Higher Shore A = harder = higher pressure. Standard durometer is 70A — verify if application requires different hardness PARTSTABLE TECHNICAL DRAWING — NOT TO SCALE
KEY FEATURES
•
DESIGN TYPE: FRICTION
•
OVERALL DIAMETER: 2.180 INCHES NOMINAL IN
•
OPENING INSIDE DIAMETER FOR WHICH DESIGNED: 2.090 INCHES MINIMUM AND 2.110 INCHES MAXIMUM IN
•
MATERIAL: PLASTIC, POLYETHYLENE (PP)
TECHNICAL CHARACTERISTICS
DESIGN TYPEFRICTION
OVERALL DIAMETER2.180 INCHES NOMINAL IN
OPENING INSIDE DIAMETER FOR WHICH DESIGNED2.090 INCHES MINIMUM AND 2.110 INCHES MAXIMUM IN
MATERIALPLASTIC, POLYETHYLENE (PP)
OTHER ITEMS IN FSC 5340 — Hardware, Commercial
Items in the same Federal Supply class. No interchangeability or substitution relationship is implied.
5340-00-000-0068 5340-00-000-0132 5340-00-000-8150 5340-00-001-1251 5340-00-001-1264 5340-00-001-1265 5340-00-001-1266 5340-00-001-1275
SUBSTITUTES & CROSS-REFERENCES 2
10176940Reference document
Same NSN cross-reference
Reference document — Informative reference only
588.40-000000-001Same NSN cross-reference
Same NSN cross-reference
Also cataloged under this NSN
LIFECYCLE
NSN statusActive· U.S. Government catalog
Acquisition advice: Insurance item — stocked against contingency demandNo demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is 639AS1021?
639AS1021 is a CAP,PROTECTIVE,DUST AND MOISTURE.
What parts can replace 639AS1021?
There are 2 known substitutes for 639AS1021: 10176940, 588.40-000000-001. Substitute compatibility should be verified for your specific system.
What is the NSN for 639AS1021?
639AS1021 is cataloged in the U.S. Government catalog under NSN 5340-01-131-0725. This indicates validated use in U.S. government and defense supply chains.
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✓ PartsTable — the parts reference. Every fact cited to its source.
PartsTable Design LLC · partstable.com
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-18.
PartsTable commercial catalog: edition Unified commercial catalog snapshot through 2026-09-28, edition date not on file, retrieved 2026-09-28.