Value Collection ZMSCH90257 O-ring Dash 257 Buna-n 90 Duro

Product Description

The VALUE COLLECTION ZMSCH90257 is a Dash 257 O-ring manufactured from Nitrile Butadiene Rubber (Buna-N), one of the most widely used elastomers in fluid sealing applications. It measures 5.875 inches inside diameter, 6.125 inches outside diameter, and 0.125 inches thick with a round cross section. Rated at 90 durometer (extra hard), it delivers strong resistance to petroleum-based fluids, excellent compression set performance, and solid tear and abrasion resistance. The temperature range spans -40 to 250 degrees F, making it suitable for a broad range of hydraulic, pneumatic, and fluid-handling systems. Licensed plumbers, pipefitters, and industrial mechanics are the primary installers.

This O-ring is used in hydraulic cylinders, pumps, valves, fittings, and fluid-transfer equipment where a petroleum-compatible seal is required. The Buna-N compound is the standard choice for sealing mineral oil, diesel fuel, water, and many common hydraulic fluids. Typical applications include industrial maintenance, plumbing assemblies, and HVAC refrigerant-adjacent sealing tasks where the fluid media is compatible with nitrile rubber. It should not be used in applications involving ozone exposure, sunlight storage, or contact with ozone-generating equipment such as electric motors.

Key Features

• Buna-N (Nitrile Butadiene Rubber) material with excellent petroleum-product resistance
• 90 durometer extra-hard rating for high-compression sealing applications
• Operating temperature range of -40 to 250 degrees F
• Round cross section per Dash 257 standard sizing
• Meets SAE and MIL-Spec standards
• Sold in a package quantity of 10

Compatibility

Compatible with petroleum products including mineral oils, hydraulic fluids, and diesel fuel. Not recommended for use with ozone-generating environments, direct sunlight exposure, or fluids outside the nitrile compatibility range. Not FDA approved.

Installation Notes

O-rings in this size range are typically installed by licensed plumbers, pipefitters, or industrial mechanics. Always depressurize and drain the system before replacing any O-ring seal. Inspect the groove and mating surfaces for scoring or corrosion before installation. Do not over-stretch the ring during installation; use an appropriate O-ring lubricant compatible with the system fluid and the nitrile material.