Difference Between NBR and FKM O-Rings

Difference Between NBR and FKM O-Rings for Industrial Sealing Applications

When selecting an O-ring material for industrial sealing applications, two of the most commonly used elastomers are NBR (Nitrile Rubber) and FKM (Fluoroelastomer, commonly known as Viton®). Both materials are widely used in hydraulic systems, pneumatic equipment, automotive components, aerospace sealing, and industrial machinery. However, each material offers different advantages depending on temperature, chemical exposure, and operating conditions.

Understanding the difference between NBR and FKM O-rings helps engineers and purchasing teams choose the right sealing material for long-term reliability and leak prevention.

What is an NBR O-Ring?

NBR (Nitrile Butadiene Rubber) is one of the most widely used sealing materials because of its excellent resistance to petroleum-based oils and fuels. NBR O-rings are cost-effective and provide reliable sealing performance in standard industrial environments.

Main Advantages of NBR O-Rings

• Excellent resistance to hydraulic oil and lubricants

• Good mechanical strength and abrasion resistance

• Economical material for general industrial use

• Suitable for pneumatic and hydraulic systems

• Wide range of hardness options

Typical Applications

• Hydraulic fittings

• Pneumatic cylinders

• Automotive fuel systems

• Industrial pumps and valves

• General machinery sealing

Temperature Range

NBR O-rings typically operate between -40°C and +120°C depending on the compound formulation.

What is an FKM O-Ring?

FKM (Fluoroelastomer) is a high-performance sealing material designed for extreme temperature and aggressive chemical environments. FKM O-rings are commonly used in aerospace, chemical processing, semiconductor, and high-temperature industrial applications.

Main Advantages of FKM O-Rings

• Excellent chemical resistance

• Outstanding heat resistance

• Superior resistance to fuels and aggressive fluids

• Long service life in harsh environments

• Excellent compression set resistance

Typical Applications

• Aerospace sealing systems

• Chemical processing equipment

• High-temperature hydraulic systems

• Fuel handling systems

• Vacuum applications

Temperature Range

FKM O-rings generally operate between -20°C and +200°C, with some specialty grades supporting even higher temperatures.

Which O-Ring Material Should You Choose?

NBR O-rings are ideal for general-purpose hydraulic and pneumatic sealing where cost efficiency and oil resistance are important. FKM O-rings are recommended for demanding environments involving high temperatures, chemicals, fuels, or aerospace applications.

For industrial sealing systems exposed to aggressive media or continuous heat, FKM provides significantly longer service life and better sealing reliability.

Roman Seal Industrial Sealing Solutions

Roman Seal Official Website manufactures industrial O-rings and sealing components for hydraulic, aerospace, automotive, and industrial applications. Available materials include NBR, FKM, EPDM, silicone, fluorosilicone, and FFKM compounds.

Roman Seal supplies custom and standard sealing solutions including:

• O-rings

• Bonded seals

• Thread seal washers

• Aerospace rubber seals

• Parker equivalent sealing products

For technical inquiries or custom sealing solutions, contact Roman Seal for engineering support and RFQ assistance.