Value Collection ZMSCH70321 O-ring Dash 321 Buna-n 70A

Product Description

The VALUE COLLECTION ZMSCH70321 is a Dash 321 O-ring made from Nitrile Butadiene Rubber (Buna-N), one of the most widely used elastomers in fluid sealing applications. It measures 1.188 inches inside diameter, 1.563 inches outside diameter, and 0.1875 inches thick with a round cross section. Rated at 70 Shore A hardness, this O-ring delivers reliable compression set resistance along with strong tear and abrasion resistance. It is suited for static and dynamic sealing in systems that handle petroleum-based fluids. Licensed trades including plumbers, HVAC technicians, and fluid-system mechanics regularly specify Buna-N O-rings as primary seals and replacement components.

This O-ring is intended for use in hydraulic, pneumatic, and fluid-handling assemblies where exposure to petroleum products, oils, and fuels is expected. Its operating temperature range of -40 degrees F to 250 degrees F makes it appropriate for a broad range of residential and commercial service conditions. Grooves machined to standard SAE and MIL-Spec Dash 321 dimensions will accept this O-ring directly. It should not be stored in direct sunlight or near motors and electrical equipment that generate ozone, as ozone exposure degrades Buna-N over time.

Key Features

• Buna-N (Nitrile Butadiene Rubber) construction — excellent resistance to petroleum products, oils, and fuels
• 70 Shore A hardness rating for firm compression set performance
• Round cross section, 0.1875 inches thick, conforming to Dash 321 sizing standard
• Operating range: -40 degrees F to 250 degrees F
• Meets SAE and MIL-Spec standards
• Strong tear and abrasion resistance for dynamic sealing environments

Compatibility

Designed for use in any standard Dash 321 O-ring groove machined to SAE or MIL-Spec tolerances. Compatible with petroleum products, hydraulic oils, and fuels. Not recommended for use with ozone-generating environments, strong acids, ketones, or esters.

Installation Notes

Plumbers, HVAC technicians, and fluid-system mechanics should shut down and depressurize the system completely before replacing any O-ring seal. Inspect the groove for nicks, burrs, or corrosion before installing the new O-ring. Light application of a compatible petroleum-based lubricant eases installation and reduces the risk of pinching or rolling the seal. Follow applicable codes — IPC, IFGC, or equipment OEM service procedures — for reassembly and pressure testing after installation.