Value Collection ZMSCHB90352 O-ring Backup Ring Nbr 90D

Product Description

The VALUE COLLECTION ZMSCHB90352 is a rectangular-cross-section backup ring O-ring made from Nitrile Butadiene Rubber (NBR), rated at 90 durometer for extra-hard hardness. It measures 4.903 inches inner diameter, 5.269 inches outer diameter, and 0.0625 inches thick (Dash 8-352). The extra-hard 90-durometer NBR compound resists extrusion under pressure and holds a reliable seal across a wide service temperature range of -40 to 250 degrees F. This part is used by licensed plumbers, HVAC technicians, and industrial maintenance professionals who require a dependable backup ring to prevent O-ring extrusion in dynamic or static sealing applications.

This backup ring is suited for hydraulic, pneumatic, and fluid-handling systems where elevated pressures can cause standard O-rings to extrude into clearance gaps. The Dash 8-352 designation corresponds to a standardized sizing convention, making cross-referencing straightforward across equipment platforms. NBR construction provides good resistance to petroleum-based oils, hydraulic fluids, and water, making this ring appropriate for a broad range of industrial and commercial mechanical assemblies. Each package contains 10 rings with a minimum order quantity of 1.

Key Features

• Rectangular cross-section backup ring design prevents primary O-ring extrusion under pressure
• Nitrile Butadiene Rubber (NBR) material offers solid resistance to petroleum oils and hydraulic fluids
• 90 durometer extra-hard rating provides firm sealing under high-stress conditions
• Rated for service from -40 to 250 degrees F, covering most industrial and HVAC fluid system ranges
• Dash 8-352 standardized sizing for easy cross-referencing and replacement
• Sold in packages of 10 rings

Compatibility

Designed as an OEM-style replacement or maintenance stock backup ring for static and dynamic sealing assemblies requiring a Dash 8-352 rectangular NBR ring with a 4.903-inch inner diameter.

Installation Notes

Installation is typically performed by licensed plumbers, HVAC technicians, or industrial mechanics. Depressurize and isolate the system fully before disassembling any fitting or housing. Inspect the groove dimensions to confirm a proper fit before seating the backup ring. Avoid stretching or twisting the ring during installation to prevent deformation that could compromise the seal.