8-333 BLACK BUNA 90D BACK-UP RING

Buna-N Back-Up Ring, 2.475 in ID x 0.21 CS, 90A, Black, -40 to 250°F

Status
Available
Est. Ship Date
31 Oct 2026
Material
Buna-N (Nitrile / NBR)
Dash Size
333
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
3/16 inch
Nominal Inside Diameter
2 1/2 inch
Nominal Outside Diameter
2 7/8 inch
Unit of Measure
EA
SKU:
HB90333
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Product Specification

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HB90333 is an AS568-333 black Buna-N (Nitrile) 90 Shore A Back-Up Ring measuring an inside diameter of 2.475 in (62.87 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 2.895 in (73.53 mm). In service, this back-up ring allows a standard o-ring to operate at higher pressures than it could unsupported.

Buna-N (Nitrile) is specified here for economical choice for high-volume maintenance programs and low compression set under sustained load. This material stands up to propane and butane, greases and lubricants, and many alcohols. Rated temperature range runs from -40°F (-40°C) to 250°F (121.1°C) in continuous service. It should not be specified for service in automotive brake fluid or strong acids.

Typical settings include automotive, fluid power, and construction equipment.

This item is sold individually under part number HB90333. Unit weight is approximately 2.2671 g and nominal inside diameter is listed as 2 1/2 inch. Review your operating media and conditions against this specification before installation. APG can cross-reference from an existing part number, a drawing or a physical sample if this size is not an exact match.
Item
HB90333
Description
8-333 BLACK BUNA 90D BACK-UP RING
Actual Cross Section
0.21 inch (5.33 mm)
Actual Inside Diameter
2.475 inch (62.87 mm)
Actual Outside Diameter
2.895 inch (73.53 mm)
FDA Compliant
No
Measurement System
Imperial
Metal Detectable
No
NSF Certified
No
Product Code
6002
Product Category
O-Rings - Backup Rings