Value Collection ZMSCHB90018 O-ring Backup Ring Nbr

Product Description

The VALUE COLLECTION ZMSCHB90018 is a rectangular-cross-section backup ring O-ring made from Nitrile Butadiene Rubber (NBR), designed to prevent extrusion and seal failure in static and dynamic fluid system applications. It measures 0.768 inches inside diameter, 0.874 inches outside diameter, and 0.0468 inches thick. With a 90 durometer hardness rating, this extra-hard ring resists compression set and deformation under pressure. It operates across a temperature range of -40 to 250 degrees F, making it suitable for a wide range of hydraulic, pneumatic, and plumbing sealing applications. Licensed plumbers, HVAC technicians, and industrial mechanics are the primary installers.

This backup ring is used in grooved or gland-fitted assemblies where a standard O-ring requires anti-extrusion support. Typical applications include hydraulic cylinder rod seals, pneumatic actuator assemblies, valve stems, and fluid connector fittings in both residential and commercial systems. The rectangular cross section allows it to seat firmly behind a primary O-ring in a two-piece seal stack, reducing blowout risk under cyclic pressure. It is sized to the Dash 8-018 standard for easy cross-referencing when sourcing replacements or building seal kits. Sold in packages of 100 units.

Key Features

• 0.768 inches ID x 0.874 inches OD x 0.0468 inches thick rectangular cross section
• 90 durometer extra-hard NBR construction resists compression set and extrusion
• Operating temperature range: -40 to 250 degrees F
• Dash 8-018 standard sizing for straightforward cross-referencing
• NBR material provides good resistance to petroleum-based fluids, oils, and hydraulic fluid
• Packaged in quantities of 100 for service kit builds and fleet maintenance

Compatibility

Designed as a standard Dash 8-018 backup ring for use in hydraulic, pneumatic, and fluid connector assemblies requiring a rectangular NBR anti-extrusion ring at 0.768 inches ID.

Installation Notes

Backup rings are installed by licensed plumbers, hydraulic technicians, or HVAC mechanics depending on the application. Always depressurize and isolate the system before disassembling any seal gland or fitting. Inspect the gland groove for burrs or damage before seating the backup ring, as surface defects can cause premature seal failure. Follow equipment manufacturer torque and reassembly procedures when closing the fitting or cylinder cap.