8-161 BLACK BUNA 90D BACK-UP RING

Buna-N Back-Up Ring, 5.487 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
161
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 1/2 inch
Nominal Outside Diameter
5 11/16 inch
Unit of Measure
EA
SKU:
HB90161
Please login to see price and add to cart

Product Specification

-
Part number HB90161 is an AS568-161 black Buna-N (Nitrile) 90 Shore A Back-Up Ring built to an inside diameter of 5.487 in (139.37 mm), a cross section of 0.103 in (2.62 mm), and an outside diameter of 5.693 in (144.6 mm). A back-up ring allows a standard o-ring to operate at higher pressures than it could unsupported.

Buna-N (Nitrile) delivers low compression set under sustained load, strong abrasion and tear resistance. The material holds up against greases and lubricants, hydraulic fluids, and propane and butane. Rated temperature range runs from -40°F (-40°C) to 250°F (121.1°C) in continuous service.

It sees regular use in automotive, general industrial maintenance, and hydraulic and pneumatic systems.

Stocked as HB90161 and sold individually. Unit weight is approximately 1.55 g and nominal inside diameter is listed as 5 1/2 inch. Check the compound against your process media, pressure and temperature before committing to a design. Not finding the exact configuration you need? APG cross-references from prints, samples and competitor part numbers.
Item
HB90161
Description
8-161 BLACK BUNA 90D BACK-UP RING
Actual Cross Section
0.103 inch (2.62 mm)
Actual Inside Diameter
5.487 inch (139.37 mm)
Actual Outside Diameter
5.693 inch (144.6 mm)
FDA Compliant
No
Measurement System
Imperial
Metal Detectable
No
NSF Certified
No
Product Code
6002
Product Category
O-Rings - Backup Rings