The HB90475 is an AS568-475 black Buna-N (Nitrile) 90 Shore A Back-Up Ring with an inside diameter of 25.94 in (658.88 mm), a cross section of 0.275 in (6.99 mm), and an outside diameter of 26.49 in (672.85 mm). This back-up ring allows a standard o-ring to operate at higher pressures than it could unsupported.
The compound resists propane and butane, many alcohols, and greases and lubricants. Buna-N (Nitrile) is widely chosen for the most widely specified general-purpose sealing elastomer and 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.
Maintenance and OEM teams specify it across automotive, agricultural equipment, and hydraulic and pneumatic systems.
Reference part number HB90475 when ordering; the item is sold individually. Review your operating media and conditions against this specification before installation.
Description 8-475 BLACK BUNA 90D BACK-UP RING
Actual Cross Section 0.275 inch (6.99 mm)
Actual Inside Diameter 25.94 inch (658.88 mm)
Actual Outside Diameter 26.49 inch (672.85 mm)
Measurement System Imperial
Product Category O-Rings - Backup Rings