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21278-0357 — SEAL,PLAIN ENCASED

✓ Government record, cited
— · ORING SEAL
PRODUCT OVERVIEW

21278-0357: SEAL,PLAIN ENCASED.

The SEAL,PLAIN ENCASED is a the manufacturer industrial component. Key specifications include material: STEEL CASE, case_style: SQUARE, seal_width: 0.375 INCHES NOMINAL IN, housing_bore_diameter: 1.875 INCHES NOMINAL IN, sealing_element_style: ANGULAR, accommodated_shaft_diameter: 1.125 INCHES NOMINAL IN. This part is cataloged in the U.S.

Government catalog under NSN 5330-00-809-9125, 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
21278-0357
NSN: 5330-00-809-9125
FSC: 5330 — Packing and Gasket Materials
CAGE: 73680 — GARLOCK SEALING TECHNOLOGIES LLC DBA GARLOCK SEALING TECHNOLOGIES LLC (USA)
SPECIFICATIONS
materialSTEEL CASE
case_styleSQUARE
seal_width0.375 INCHES NOMINAL IN
housing_bore_diameter1.875 INCHES NOMINAL IN
sealing_element_styleANGULAR
accommodated_shaft_diameter1.125 INCHES NOMINAL IN
accommodated_shaft_maximum_rated_speed3000 FEET PER MINUTE FT
NSN5330-00-809-9125
COMPONENT DIAGRAM
O-RING / SEAL — MATERIAL DETERMINES APPLICATION ID: — CROSS-SECTION CS: — SPECIFICATION Material: — Durometer: — Temp: — PN: 21278-0357 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
•
SEAL WIDTH: 0.375 INCHES NOMINAL IN
•
SEALING ELEMENT STYLE: ANGULAR
•
HOUSING BORE DIAMETER: 1.875 INCHES NOMINAL IN
•
ACCOMMODATED SHAFT MAXIMUM RATED SPEED: 3000 FEET PER MINUTE FT
•
CASE STYLE: SQUARE
•
ACCOMMODATED SHAFT DIAMETER: 1.125 INCHES NOMINAL IN
•
MATERIAL: STEEL CASE
TECHNICAL CHARACTERISTICS
SEAL WIDTH0.375 INCHES NOMINAL IN
SEALING ELEMENT STYLEANGULAR
HOUSING BORE DIAMETER1.875 INCHES NOMINAL IN
ACCOMMODATED SHAFT MAXIMUM RATED SPEED3000 FEET PER MINUTE FT
CASE STYLESQUARE
ACCOMMODATED SHAFT DIAMETER1.125 INCHES NOMINAL IN
MATERIALSTEEL CASE
MATERIALRUBBER SYNTHETIC SEALING ELEMENT
SUBSTITUTES & CROSS-REFERENCES 2
CB50-4Same NSN cross-reference
Same NSN cross-reference
Also cataloged under this NSN
65X0357Same NSN cross-reference
Same NSN cross-reference
Also cataloged under this NSN
LIFECYCLE
NSN statusActive· U.S. Government catalog
No demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is 21278-0357?
21278-0357 is a SEAL,PLAIN ENCASED.
What parts can replace 21278-0357?
There are 2 known substitutes for 21278-0357: CB50-4, 65X0357. Substitute compatibility should be verified for your specific system.
What is the NSN for 21278-0357?
21278-0357 is cataloged in the U.S. Government catalog under NSN 5330-00-809-9125. 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.