Value Collection ZMSCHB90328 O-ring Backup Ring Nbr 25 Pack

Product Description

The VALUE COLLECTION ZMSCHB90328 is a Dash 8-328 rectangular cross-section backup ring O-ring made from Nitrile Butadiene Rubber (NBR). It measures 1.888 inches inner diameter by 2.254 inches outer diameter with a thickness of 0.0625 inches (1/16 inch). Rated at 90 durometer, this extra-hard seal is designed for use as a backup ring in hydraulic and pneumatic systems where standard O-rings require anti-extrusion support. Plumbers, millwrights, and fluid-power technicians install this type of seal during valve, cylinder, and fitting service. Each package contains 25 rings. The material handles a temperature range of -40 degrees F to 250 degrees F, making it suitable for a broad range of fluid system environments.

This backup ring is used in applications where system pressure would cause a standard O-ring to extrude past a gap or clearance. Typical install scenarios include hydraulic cylinder rod and piston grooves, pneumatic valve bodies, and high-pressure plumbing fittings. The NBR compound provides good resistance to petroleum-based oils, hydraulic fluids, fuels, and water. It is not intended for use with phosphate-ester fluids, ketones, or ozone-exposed environments. The rectangular cross section seats firmly in standard O-ring grooves sized for Dash 328 geometry.

Key Features

• Dash 8-328 standard geometry: 1.888 inches ID, 2.254 inches OD, 0.0625 inches thick
• 90 durometer extra-hard rating provides anti-extrusion performance under elevated pressure
• NBR compound rated from -40 degrees F to 250 degrees F
• Rectangular cross section for use as a backup ring alongside standard O-rings
• Sold in a 25-piece package with a minimum order quantity of 1

Compatibility

Designed as a standard Dash 8-328 backup ring for hydraulic and pneumatic systems requiring an anti-extrusion seal in grooves sized to Dash 328 dimensions.

Installation Notes

Installation is typically performed by hydraulic technicians, millwrights, or licensed plumbers during cylinder, valve, or fitting service. Depressurize and isolate the system completely before disassembling any sealed joint. Inspect the groove and mating surfaces for burrs or scoring before seating the ring. Do not twist or roll the backup ring during installation, as deformation can compromise the seal.