The Buna-N (Nitrile) 90A Durometer Hydraulic O-Ring is engineered for demanding hydraulic and pneumatic sealing applications where standard durometer compounds fall short. With a Shore A hardness of 90, this o-ring delivers superior extrusion resistance under high-pressure conditions, making it the go-to choice for heavy-duty industrial systems.
Key Features
Material: Buna-N (NBR / Nitrile Butadiene Rubber)
Durometer: 90 Shore A — harder compound for high-pressure, low-clearance applications
Temperature Range: -40°F to +250°F (-40°C to +121°C)
Pressure Rating: Suitable for high-pressure hydraulic systems; extrusion resistance superior to standard 70A compounds
Fluid Compatibility: Petroleum-based hydraulic oils, mineral oils, diesel fuel, water-glycol fluids, and most aliphatic hydrocarbons
Standards: Available in AS568 dash sizes
Ideal Applications
Hydraulic cylinders and actuators
High-pressure fittings and manifolds
Pumps, valves, and motors
Mobile hydraulic equipment
Industrial machinery and presses
Why 90A Durometer?
When operating pressures exceed 1,500 PSI or clearance gaps are larger than standard tolerances allow, a 90A compound prevents the o-ring from extruding into the gap — extending seal life and preventing system failure. Pair with a back-up ring for extreme pressure applications.
