Value Collection ZMSCHB90350 Nbr O-ring Dash 8-350 90 Duro

Product Description

The VALUE COLLECTION ZMSCHB90350 is a rectangular-cross-section nitrile butadiene rubber (NBR) backup ring designed to prevent O-ring extrusion under pressure in hydraulic and pneumatic sealing applications. It measures 4.653 inches inside diameter, 5.019 inches outside diameter, and 0.0625 inches thick. At a 90 durometer hardness rating, this is an extra-hard compound suited for high-pressure systems where a standard O-ring alone may deform or blow out of its groove. Licensed plumbers, hydraulic technicians, and industrial maintenance pros install these as part of a two-piece seal stack. The NBR compound handles a temperature range of -40 to 250 degrees F.

This backup ring is used wherever an NBR O-ring of the Dash 8-350 size is installed in a high-pressure or dynamic sealing application. Typical installations include hydraulic cylinders, actuators, manifold ports, and large-diameter fluid fittings in industrial, plumbing, and HVAC-adjacent systems. The rectangular cross section seats flush against the low-pressure side of the O-ring groove, blocking extrusion into the clearance gap. It is sold in packages of 10, making it practical to stock for maintenance and repair work.

Key Features

• Rectangular cross section prevents O-ring extrusion on the low-pressure side of the groove
• 90 durometer extra-hard NBR compound resists deformation under elevated system pressure
• NBR material compatible with petroleum-based hydraulic fluids, water, and common industrial media
• Rated for -40 to 250 degrees F continuous service
• Dash 8-350 designation for straightforward cross-reference to groove specifications
• Packaged in quantities of 10 for bench stock and field repair kits

Compatibility

Designed as a standard Dash 8-350 backup ring for use with matching NBR O-rings in hydraulic, pneumatic, and fluid-sealing assemblies requiring a 4.653 inch inside diameter seal.

Installation Notes

Installation is typically performed by licensed plumbers, hydraulic technicians, or industrial mechanics. Always depressurize and de-energize the system and relieve any stored hydraulic pressure before disassembling seal housings. Backup rings are installed on the downstream or low-pressure side of the O-ring within the groove; incorrect orientation will not provide extrusion protection. Inspect the groove dimensions and surface finish before installation to confirm fit and avoid ring damage during assembly.