8-275 BLACK BUNA 90D BACK-UP RING

Buna-N Back-Up Ring, 10.484 in ID x 0.139 CS, 90A, Black, -40 to 250°F

Status
Available
Est. Ship Date
31 Oct 2026
Material
Buna-N (Nitrile / NBR)
Dash Size
275
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
1/8 inch
Nominal Inside Diameter
10 1/2 inch
Nominal Outside Diameter
10 3/4 inch
Unit of Measure
EA
SKU:
HB90275
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Product Specification

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HB90275 is an AS568-275 black Buna-N (Nitrile) 90 Shore A Back-Up Ring measuring an inside diameter of 10.484 in (266.29 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 10.762 in (273.35 mm). In service, this back-up ring allows a standard o-ring to operate at higher pressures than it could unsupported.

The compound resists petroleum-based oils, propane and butane, and water. Buna-N (Nitrile) is known for an economical choice for high-volume maintenance programs, strong abrasion and tear resistance. The material carries a published service range of -40°F (-40°C) to 250°F (121.1°C). Applications involving ketones or ozone and direct sunlight call for a different compound.

Common environments for this compound include construction equipment, general industrial maintenance, and automotive.

Reference part number HB90275 when ordering; the item is sold individually. Unit weight is approximately 3.852 g and nominal inside diameter is listed as 10 1/2 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
HB90275
Description
8-275 BLACK BUNA 90D BACK-UP RING
Actual Cross Section
0.139 inch (3.53 mm)
Actual Inside Diameter
10.484 inch (266.29 mm)
Actual Outside Diameter
10.762 inch (273.35 mm)
FDA Compliant
No
Measurement System
Imperial
Metal Detectable
No
NSF Certified
No
Product Code
6002
Product Category
O-Rings - Backup Rings