8-109 BLACK BUNA 90D BACK-UP RING

Buna-N Back-Up Ring, 0.299 in ID x 0.103 CS, 90A, Black, -40 to 250°F

Status
Available
Est. Ship Date
31 Oct 2026
Material
Buna-N (Nitrile / NBR)
Dash Size
109
Durometer
90 Shore A
Cross Section Type
Round
Color
Black
Minimum Temperature
-40°F (-40°C)
Maximum Temperature
250°F (121°C)
Nominal Cross Section
3/32 inch
Nominal Inside Diameter
5/16 inch
Nominal Outside Diameter
1/2 inch
Unit of Measure
EA
SKU:
HB90109
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Product Specification

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This back-up ring is supplied in AS568-109 black Buna-N (Nitrile) 90 Shore A built to an inside diameter of 0.299 in (7.59 mm), a cross section of 0.103 in (2.62 mm), and an outside diameter of 0.505 in (12.83 mm), catalogued under part number HB90109. It allows a standard o-ring to operate at higher pressures than it could unsupported.

Buna-N (Nitrile) is specified here for most widely specified general-purpose sealing elastomer, reliable performance in both static and dynamic service. Expect good resistance to many alcohols, greases and lubricants, and water. Continuous operating temperature is published at -40°F (-40°C) to 250°F (121.1°C). Verify compatibility before use with strong acids or automotive brake fluid.

Typical settings include agricultural equipment, fluid power, and hydraulic and pneumatic systems.

This item is sold individually under part number HB90109. Unit weight is approximately 0.124 g and nominal inside diameter is listed as 5/16 inch. Review your operating media and conditions against this specification before installation. Not finding the exact configuration you need? APG cross-references from prints, samples and competitor part numbers.
Item
HB90109
Description
8-109 BLACK BUNA 90D BACK-UP RING
Actual Cross Section
0.103 inch (2.62 mm)
Actual Inside Diameter
0.299 inch (7.59 mm)
Actual Outside Diameter
0.505 inch (12.83 mm)
FDA Compliant
No
Measurement System
Imperial
Metal Detectable
No
NSF Certified
No
Product Code
6002
Product Category
O-Rings - Backup Rings