Value Collection ZMSCHB90345 O-ring Backup Ring Nbr Dash 8-345

Product Description

The VALUE COLLECTION ZMSCHB90345 is a rectangular-cross-section backup ring O-ring made from Nitrile Butadiene Rubber (NBR), rated at 90 durometer for extra-hard sealing performance. With an inside diameter of 4.28 inches, an outside diameter of 4.394 inches, and a thickness of 0.0625 inches, this ring is sized to the Dash 8-345 standard. It handles a working temperature range of -40 to 250 degrees F, making it suitable for a wide range of fluid sealing applications. Licensed tradespeople in plumbing, HVAC, hydraulic, and industrial maintenance use this type of component to prevent seal extrusion in high-pressure assemblies.

This backup ring is designed for use in applications where a standard O-ring requires anti-extrusion support under pressure or elevated temperature cycling. Its rectangular cross section seats firmly against groove walls to minimize gap intrusion. The NBR compound provides solid resistance to petroleum-based fluids, oils, and many hydraulic fluids. Typical install scenarios include pump assemblies, valve bodies, cylinder bores, and fluid line couplings in both residential and light commercial mechanical systems. Sold in a package quantity of 10 with a minimum order quantity of 1.

Key Features

• Rectangular cross section provides anti-extrusion backup support in high-pressure groove applications
• 90 durometer extra-hard NBR compound resists deformation under sustained load
• Dash 8-345 standard sizing ensures consistent groove fitment across compliant assemblies
• Wide temperature range of -40 to 250 degrees F supports use in both cold and elevated-heat environments
• NBR material offers reliable resistance to petroleum oils and hydraulic fluids
• Packaged in quantities of 10 to support multi-unit servicing or replacement stock

Compatibility

Designed as an OEM-style replacement or service component for any assembly specifying a Dash 8-345 rectangular backup ring with a 4.28-inch ID, 4.394-inch OD, and 0.0625-inch thickness in NBR material.

Installation Notes

Installation should be performed by a qualified mechanic, plumber, or HVAC technician following the equipment manufacturer's service procedures. De-energize all pressure and power sources before disassembling any sealed assembly. Inspect the groove for burrs, scoring, or contamination before seating the backup ring, and never stretch or twist the ring during installation. This part is not FDA approved and should not be used in food-contact or potable-water applications.