Value Collection ZMSCHB90239 O-ring Dash 8-239 Nbr

Product Description

The VALUE COLLECTION ZMSCHB90239 is a rectangular-cross-section backup O-ring made from Nitrile Butadiene Rubber (NBR), designed to prevent extrusion in hydraulic and pneumatic sealing applications. It carries a Dash 8-239 designation and measures 3.631 inches inner diameter by 3.867 inches outer diameter with a thickness of 0.0468 inches. At 90 durometer, this extra-hard ring provides firm support behind a primary O-ring under pressure, holding the seal in place and extending service life. It is installed by maintenance technicians, hydraulic system specialists, and plumbing professionals working on equipment subject to fluid or gas pressure cycling.

This backup ring suits residential and commercial applications wherever a Dash 8-239 backup ring is specified, including hydraulic cylinders, pneumatic actuators, fluid fittings, and valve assemblies. Its NBR compound handles a broad range of petroleum-based fluids, water, and general-purpose gases. The wide temperature range of -40 to 250 degrees F makes it suitable for both cold-climate outdoor equipment and moderate-heat process systems. Each order unit contains 10 rings, and the minimum order quantity is 1 unit.

Key Features

• Rectangular cross section functions as a backup ring to resist extrusion of primary O-ring seals under pressure
• Nitrile Butadiene Rubber (NBR) compound compatible with petroleum-based fluids, water, and general-purpose gases
• 90 durometer extra-hard rating provides firm lateral support in high-pressure groove configurations
• Operating temperature range of -40 to 250 degrees F suits a wide variety of service environments
• Dash 8-239 designation allows direct cross-reference to standard O-ring sizing charts
• Packaged in quantities of 10 rings per unit for bench stock and service kit replenishment

Compatibility

Designed as a standard Dash 8-239 backup ring for use in hydraulic, pneumatic, and fluid-sealing assemblies that specify an NBR rectangular backup ring with a 3.631-inch inner diameter and 0.0468-inch thickness. Not FDA approved; not intended for food-contact or pharmaceutical applications.

Installation Notes

Backup rings are typically installed by hydraulic technicians or plumbers during seal kit replacement with the system fully depressurized and the fluid supply isolated. Inspect the groove dimensions before installation to confirm the backup ring seats flush without distortion. Avoid using sharp tools that can nick the rubber, as surface damage reduces sealing effectiveness. Follow the equipment manufacturer's torque specifications and applicable codes when reassembling fittings and housings.