8-471 BLACK BUNA 90D BACK-UP RING

Buna-N Back-Up Ring, 21.955 in ID x 0.275 CS, 90A, Black, -40 to 250°F

Status
Available
Est. Ship Date
31 Oct 2026
Material
Buna-N (Nitrile / NBR)
Dash Size
471
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
1/4 inch
Nominal Inside Diameter
22 inch
Nominal Outside Diameter
22 1/2 inch
Unit of Measure
EA
SKU:
HB90471
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Product Specification

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This back-up ring is supplied in AS568-471 black Buna-N (Nitrile) 90 Shore A with an inside diameter of 21.955 in (557.66 mm), a cross section of 0.275 in (6.99 mm), and an outside diameter of 22.505 in (571.63 mm), catalogued under part number HB90471. It installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.

Buna-N (Nitrile) is specified for the most widely specified general-purpose sealing elastomer and an economical choice for high-volume maintenance programs. It resists hydraulic fluids, propane and butane, and many alcohols. The material carries a published service range of -40°F (-40°C) to 250°F (121.1°C).

Common environments for this compound include hydraulic and pneumatic systems, fluid power, and automotive.

Stocked as HB90471 and sold individually. Unit weight is approximately 37.8933 g and nominal inside diameter is listed as 22 inch. Application requirements vary, so validate compatibility with your process conditions prior to installation. For a size or compound outside the standard catalog, APG can quote from a print or sample.
Item
HB90471
Description
8-471 BLACK BUNA 90D BACK-UP RING
Actual Cross Section
0.275 inch (6.99 mm)
Actual Inside Diameter
21.955 inch (557.66 mm)
Actual Outside Diameter
22.505 inch (571.63 mm)
FDA Compliant
No
Measurement System
Imperial
Metal Detectable
No
NSF Certified
No
Product Code
6002
Product Category
O-Rings - Backup Rings