Ordered as VBU90234, this is an AS568-234 black Viton® (FKM) 90 Shore A Back-Up Ring supplied with an inside diameter of 2.984 in (75.79 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 3.262 in (82.85 mm). The back-up ring bridges the extrusion gap so the primary seal holds its shape under load.
Viton® (FKM) is specified for the industry benchmark where nitrile reaches its thermal limit and long service life in hot, chemically aggressive environments. Expect good resistance to petroleum oils and fuels, many acids, and aromatic hydrocarbons. Continuous operating temperature is published at -15°F (-26.1°C) to 400°F (204.4°C). It is not the right choice where hot water and steam or amines are present.
You will find this material specified across oil and gas, automotive fuel systems, and semiconductor equipment.
Order part number VBU90234, sold individually. Unit weight is approximately 1.5122 g. 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.
description 8-234 BLACK FKM 90D BACK-UP RING
Actual_CS 0.139 inch (3.53 mm)
Actual_ID 2.984 inch (75.79 mm)
Actual_OD 3.262 inch (82.85 mm)
ProductCode Description O-Rings - Backup Rings