NBR as a practical industrial choice
NBR is commonly selected for mineral oils and general hydraulic service. It offers a useful balance of cost, wear performance and availability.
When FKM may be appropriate
FKM is often considered when higher temperature or broader chemical resistance is required. Actual suitability still depends on the exact fluid and operating conditions.
Do not select by material name alone
Compound formulation, hardness, geometry and production control all matter. Ask for a recommendation against your application data instead of assuming every grade performs the same.