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D139-18-954ITEM9 — O-RING

✓ Government record, cited
— · ORING SEAL
PRODUCT OVERVIEW

D139-18-954ITEM9: O-RING.

The O-RING is a the manufacturer industrial component. Key specifications include material: RUBBER BUTADIENE-ACRYLONITRILE CLASS NBR, center_hole_diameter: 1.875 INCHES NOMINAL IN, cross-sectional_height: 0.125 INCHES NOMINAL IN, end_item_identification: 18-IN FIGURE 139 BUTTERFLY VALVE, part_name_assigned_by_controlling_agency: SEAT O-RING. This part is cataloged in the U.S.

Government catalog under NSN 5331-01-554-5879, 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
D139-18-954ITEM9
NSN: 5331-01-554-5879
FSC: 5331 — O-ring
CAGE: 04613 — EMERSON AUTOMATION SOLUTIONS FINAL CONTROL US LP (USA)
SPECIFICATIONS
materialRUBBER BUTADIENE-ACRYLONITRILE CLASS NBR
center_hole_diameter1.875 INCHES NOMINAL IN
cross-sectional_height0.125 INCHES NOMINAL IN
end_item_identification18-IN FIGURE 139 BUTTERFLY VALVE
part_name_assigned_by_controlling_agencySEAT O-RING
NSN5331-01-554-5879
COMPONENT DIAGRAM
O-RING / SEAL — MATERIAL DETERMINES APPLICATION ID: — CROSS-SECTION CS: — SPECIFICATION Material: — Durometer: — Temp: — PN: D139-18-954ITEM9 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
•
CROSS-SECTIONAL HEIGHT: 0.125 INCHES NOMINAL IN
•
COLOR: BLACK
•
CENTER HOLE DIAMETER: 1.875 INCHES NOMINAL IN
•
MATERIAL: RUBBER BUTADIENE-ACRYLONITRILE CLASS NBR
TECHNICAL CHARACTERISTICS
CROSS-SECTIONAL HEIGHT0.125 INCHES NOMINAL IN
COLORBLACK
CENTER HOLE DIAMETER1.875 INCHES NOMINAL IN
PART NAME ASSIGNED BY CONTROLLING AGENCYSEAT O-RING
END ITEM IDENTIFICATION18-IN FIGURE 139 BUTTERFLY VALVE
MATERIALRUBBER BUTADIENE-ACRYLONITRILE CLASS NBR
OTHER ITEMS IN FSC 5331 — O-ring
Items in the same Federal Supply class. No interchangeability or substitution relationship is implied.
5331-00-001-1971 5331-00-001-1979 5331-00-001-3904 5331-00-001-3905 5331-00-001-3906 5331-00-001-3908 5331-00-001-3923 5331-00-001-3924
SUBSTITUTES & CROSS-REFERENCES

No substitute or cross-reference records for this part.

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 D139-18-954ITEM9?
D139-18-954ITEM9 is a O-RING.
What is the NSN for D139-18-954ITEM9?
D139-18-954ITEM9 is cataloged in the U.S. Government catalog under NSN 5331-01-554-5879. 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.