Midland Industries 400110 Sae Boss O-ring 7/8 in Fkm

Product Description

The MIDLAND INDUSTRIES 400110 is an FKM SAE Boss O-Ring designed for sealing hydraulic fittings at a 90-degree SAE Boss connection point. FKM (fluoroelastomer) construction gives this O-Ring strong resistance to heat, petroleum-based fluids, and hydraulic oils. It carries a maximum temperature rating of 375 degrees F, making it suitable for demanding hydraulic service conditions. The 7/8-14 thread size matches the corresponding SAE Boss port, and the ring seats into the boss face to create a leak-free static seal. Hydraulic system technicians and fluid power mechanics install this type of seal during fitting assembly, hose replacement, or port plug service.

This O-Ring fits 7/8-14 SAE straight-thread Boss ports commonly found in mobile hydraulic equipment, industrial machinery, and fluid power systems. It is used wherever an FKM compound is specified in place of a standard Buna-N ring, particularly in systems running elevated temperatures or aggressive hydraulic fluids. The imperial measurement system sizing aligns with standard SAE Boss port tooling and fitting hardware used across North American hydraulic applications.

Key Features

• FKM fluoroelastomer compound rated to 375 degrees F for high-temperature hydraulic service
• 7/8 inch inside diameter sized for 7/8-14 SAE Boss straight-thread ports
• 90-degree SAE Boss connection profile for reliable face-seal seating
• Imperial measurement sizing compatible with standard SAE Boss fittings and port tooling
• Lightweight at approximately 0.01 pounds for easy single-unit handling and inventory

Compatibility

Designed for use with 7/8-14 SAE Boss straight-thread port fittings in hydraulic systems requiring an FKM O-Ring seal. Confirm port thread size and O-Ring groove dimensions before installation.

Installation Notes

A licensed hydraulic technician or fluid power mechanic should depressurize and bleed the hydraulic system fully before removing any fitting or seal. Lubricate the O-Ring lightly with a compatible hydraulic fluid or clean petroleum jelly before seating it in the boss groove to prevent rolling or cutting during thread engagement. Do not reuse a removed O-Ring. Torque the fitting to the port per the fitting manufacturer's published specifications for the thread size.