Value Collection ZMSCHB90242 O-ring Backup Ring Nbr

Product Description

The VALUE COLLECTION ZMSCHB90242 is a rectangular-cross-section backup ring O-ring made from Nitrile Butadiene Rubber (NBR), designed to prevent extrusion and seal degradation in static and dynamic sealing applications. It measures 4.6 inches inside diameter with a 0.0468-inch thickness and carries a Dash 8-242 designation. Rated at 90 durometer (Extra Hard), this backup ring handles temperature ranges from -40 to 250 degrees F, making it suited for hydraulic, pneumatic, and fluid-handling systems in demanding service environments. Sold in a package quantity of 10 per order.

This backup ring is used in industrial, HVAC, plumbing, and fluid-power applications where standard O-rings require additional support against extrusion under pressure. It installs alongside primary O-rings in grooved fittings, cylinder end caps, valve bodies, and similar assemblies. The NBR material resists petroleum-based oils, fuels, and water-based fluids, making it a common choice for hydraulic cylinders, pneumatic actuators, and refrigerant-side components in commercial and residential systems. Technicians and tradespeople sourcing Dash 8-242 profile backup rings will find this part fits standard groove geometries for that dash number.

Key Features

• Rectangular cross-section profile functions as a backup ring to prevent primary O-ring extrusion under pressure
• Nitrile Butadiene Rubber (NBR) construction resists petroleum-based oils, fuels, and water-based fluids
• 90 durometer Extra Hard rating provides dimensional stability under high-pressure loading
• Operating temperature range of -40 to 250 degrees F suits a wide range of mechanical and HVAC applications
• Dash 8-242 designation ensures compatibility with standard Dash 8-242 groove dimensions
• Package quantity of 10 supports service kit builds and batch repairs

Compatibility

Designed as an OEM-style replacement backup ring for any assembly requiring a Dash 8-242 rectangular NBR backup ring with a 4.6-inch inside diameter and 90-durometer hardness rating.

Installation Notes

Installation is typically performed by licensed HVAC technicians, plumbers, or industrial mechanics. Always depressurize and lock out the system before disassembling any sealing surface. Inspect the groove and mating bore for burrs or contamination before seating the backup ring. Avoid twisting or overstretching the ring during installation, as this can compromise its sealing function.