Value Collection ZMSCH90243 O-ring Dash 243 Nbr 90A

Product Description

The VALUE COLLECTION ZMSCH90243 is a Dash 243 O-ring made from Nitrile Butadiene Rubber (Buna-N), designed for static and dynamic sealing applications in hydraulic, pneumatic, and fluid-handling systems. It measures 4.125 inches inner diameter by 4.375 inches outer diameter with a 0.125-inch cross-section thickness. The compound is rated at 90 durometer (extra hard), placing it firmly in the high-hardness range suited for elevated-pressure environments. Operating temperature range spans -40 degrees F to 250 degrees F. This O-ring is typically installed by plumbers, HVAC technicians, and industrial maintenance mechanics working on fluid and gas sealing connections.

This O-ring fits Dash 243 standard-dimension grooves and is compatible with petroleum-based hydraulic fluids, oils, and fuels. The Buna-N elastomer makes it suitable for use in fuel systems, hydraulic cylinders, pumps, valves, and fittings where petroleum product exposure is a consistent service condition. It is not recommended for use with ozone-heavy environments, direct sunlight exposure during storage, or near motors and electrical equipment that may generate ozone. Conforms to SAE and MIL-Spec standards applicable to this O-ring series.

Key Features

• Buna-N (Nitrile Butadiene Rubber) compound — the most widely used O-ring elastomer for petroleum-service applications
• 90 durometer extra-hard rating for elevated-pressure sealing performance
• Operating range of -40 degrees F to 250 degrees F suits a broad range of service temperatures
• Excellent resistance to petroleum products, compression set, tear, and abrasion
• Conforms to SAE and MIL-Spec dimensional and material standards
• Round cross-section, Dash 243 sizing for drop-in groove compatibility

Compatibility

Designed as a standard Dash 243 replacement O-ring for use in grooves sized to 4.125 inches ID with a 0.125-inch cross-section. Compatible with petroleum products including hydraulic oils, fuels, and lubricants. Not FDA approved — not intended for food, beverage, or pharmaceutical contact applications.

Installation Notes

De-energize and depressurize the system fully before removing the old O-ring or installing a replacement. Lightly lubricate the O-ring with a compatible fluid or grease before seating it in the groove to prevent twisting or nicking during assembly. Inspect the groove for burrs, scoring, or contamination that could compromise the seal. Follow SAE and applicable industry standards for groove dimensions and surface finish when replacing O-rings in hydraulic or pneumatic assemblies.