8-343 BLACK BUNA 90D BACK-UP RING

Buna-N Back-Up Ring, 3.725 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
343
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
3 3/4 inch
Nominal Outside Diameter
4 1/8 inch
Unit of Measure
EA
SKU:
HB90343
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Product Specification

-
APG stocks the HB90343, an AS568-343 black Buna-N (Nitrile) 90 Shore A Back-Up Ring with an inside diameter of 3.725 in (94.62 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 4.145 in (105.28 mm). A back-up ring allows a standard o-ring to operate at higher pressures than it could unsupported.

This material stands up to many alcohols, hydraulic fluids, and water. Buna-N (Nitrile) delivers strong abrasion and tear resistance, an economical choice for high-volume maintenance programs. Rated temperature range runs from -40°F (-40°C) to 250°F (121.1°C) in continuous service. Applications involving polar solvents or strong acids call for a different compound.

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

Reference part number HB90343 when ordering; the item is sold individually. Unit weight is approximately 3.2953 g. Application requirements vary, so validate compatibility with your process conditions prior to installation.
Item
HB90343
Description
8-343 BLACK BUNA 90D BACK-UP RING
Actual Cross Section
0.21 inch (5.33 mm)
Actual Inside Diameter
3.725 inch (94.62 mm)
Actual Outside Diameter
4.145 inch (105.28 mm)
FDA Compliant
No
Measurement System
Imperial
Metal Detectable
No
NSF Certified
No
Product Code
6002
Product Category
O-Rings - Backup Rings