Value Collection ZMSCHB90440 O-ring Backup Ring Nbr Dash 8-440

Product Description

The VALUE COLLECTION ZMSCHB90440 is a rectangular cross-section backup ring O-ring made from Nitrile Butadiene Rubber (NBR), designed to prevent extrusion and maintain seal integrity in high-pressure hydraulic and pneumatic applications. It measures 6.774 inches inside diameter, 7.246 inches outside diameter, and 0.0937 inches thick, with a 90 durometer extra-hard hardness rating. The Dash 8-440 designation confirms it meets standard sizing for backup ring applications. It is rated for operating temperatures from -40 degrees F to 250 degrees F, making it suitable for a broad range of service environments encountered in industrial, HVAC, plumbing, and fluid-handling systems.

This backup ring is used in applications where standard O-rings require additional support against extrusion under pressure. Typical installations include hydraulic cylinders, pneumatic actuators, valve assemblies, and fluid fittings where the rectangular cross-section provides a rigid anti-extrusion barrier behind a primary sealing O-ring. The NBR compound offers solid resistance to petroleum-based oils, fuels, and common hydraulic fluids, making it a practical choice for trade professionals working on mechanical systems that handle oil or water-based media. Each package contains 5 pieces.

Key Features

• Rectangular cross-section profile functions as a backup ring to prevent O-ring extrusion under pressure
• Nitrile Butadiene Rubber material provides resistance to petroleum oils, hydraulic fluids, and water
• 90 durometer extra-hard rating delivers firm support in high-pressure sealing assemblies
• Wide temperature range of -40 degrees F to 250 degrees F suits varied service conditions
• Dash 8-440 sizing conforms to standard backup ring dimensional specifications
• Sold in a package of 5 pieces with a minimum order quantity of 1 package

Compatibility

Designed as a standard Dash 8-440 backup ring for use in hydraulic, pneumatic, and fluid-handling assemblies requiring an NBR rectangular-section anti-extrusion ring with a 6.774-inch inside diameter.

Installation Notes

Backup rings are typically installed by licensed mechanics, pipefitters, or hydraulic system technicians working on pressurized assemblies. Always depressurize and lock out the system before disassembling any seal gland or fitting. Inspect the gland groove dimensions against the ring specifications before installation to confirm fit. Avoid twisting or nicking the ring during installation, as surface damage can compromise its anti-extrusion function.