FKM O-ring

The FKM O-ring is a sealing element made from fluorocarbon rubber. It is specifically developed to withstand harsh conditions. With its excellent chemical resistance and temperature range up to +200°C, this O-ring is ideal for industrial use. FKM is also known by names such as FPM or Viton®. It offers resistance to oils, greases, fuels, acids, bases and ozone. This makes it truly stand out in sectors like the chemical and pharmaceutical industries. Even when exposed to aggressive substances for extended periods, the FKM o ring retains its shape and elasticity. Whether for static or dynamic sealing, with an FKM O-ring, durability and quality under tough conditions are guaranteed.

What is FKM?

FKM is also known as fluorocarbon rubber. It is a synthetic elastomer with a high concentration of fluorine. The material was developed in the 1950s and is known for its strong resistance to chemicals, high temperatures and aging. The FKM O-ring consists of copolymers, terpolymers or tetrapolymers with a fluorine content of 65 to 71 percent. Well-known designations include FPM (according to ISO 1629) and Viton®. Thanks to its flexible composition, FKM O-rings can be tailored to specific uses such as seals in the chemical and pharmaceutical industries. An FKM O ring is a versatile seal that can be used across a wide range of services. This makes it a reliable sealing choice for the most critical applications. The phrase fkm viton often helps clarify its identity in industrial use.

Chemical composition and origin

An FKM O-ring is made from a copolymer based on highly fluorinated hydrocarbons. Its chemical structure provides strong resistance to aggressive substances and extreme temperatures. Originally developed by DuPont and later refined by Chemours, this material is sold under the brand name Viton®. Depending on the application, the FKM O-ring is manufactured as a co-, ter- or tetrapolymer. These have a fluorine content ranging from 65 to 71 percent. This allows the FKM o ring to be tailored to meet specific sealing requirements.

FPM, FKM or Viton®

The terms FPM, FKM and Viton® all refer to the same material: fluorocarbon rubber. FKM is the official designation according to ASTM standards, while FPM is used according to ISO standards. Viton® is the brand name used by Chemours and is recognized worldwide. So an FKM O-ring and a viton o ring are technically the same product. The difference lies only in the naming conventions used in different regions or by different manufacturers. No matter which term is used, an FKM o ring guarantees excellent chemical and thermal resistance.

Characteristics of FKM O-rings

The FKM O-ring is known for its performance in demanding environments. The material withstands temperatures from -20 °C to +200 °C, and special variants remain flexible down to -40 °C. In addition, FKM O-rings offer impressive protection against substances like oils, greases, fuels, acids, bases and solvents. Even during long-term exposure to ozone, UV radiation and aging, they retain their shape and elasticity. This makes the FKM O ring suitable for multiple sectors including chemical, pharmaceutical and process industries. With a combination of thermal stability, mechanical strength and chemical resistance, this FKM o ring is considered a highly reliable seal—even in the most rugged environments.

Temperature resistance

An FKM O-ring offers excellent temperature resistance, making it suitable for use in both hot and cold conditions. Standard FKM O-rings operate in a range from -20 °C to +200 °C, while special types remain flexible down to -40 °C or can withstand peaks above 200 °C. This wide usability makes the FKM o ring ideal for applications where thermal stability is critical, such as in the chemical industry, processing installations and other demanding environments.

Chemical resistance

An FKM O-ring provides strong protection against a wide range of fluids including oils, greases, fuels, solvents, acids and bases. This makes the material well-suited for use in many industrial areas. Even when exposed to chemical media over long periods, the FKM O-ring retains its quality. However, there are some limitations. The material is less resistant to polar solvents such as MEK and ethyl acetate, as well as to superheated steam. Therefore, it is important to select the right material for each specific case. When comparing viton vs fkm, these distinctions become particularly important in critical environments.

Aging and ozone resistance

The FKM O-ring is known for its resistance to aging, ozone and UV radiation. Even under constant exposure to harmful substances, the material retains its form and elastic properties. This makes the FKM O-ring highly suitable for outdoor use or installations that operate in continuous contact with fluids, without compromising sealing performance.

Use of FKM O-rings

The FKM O-ring is used across industries where chemical resistance and temperature stability are critical. In the chemical industry, it is perfect for sealing pipelines, valves and pumps that are exposed to corrosive substances. In the pharmaceutical sector, certified compounds offer reliable sealing for direct product contact. Thanks to its durability, the FKM O ring also performs well in process installations and technical systems under high temperature and pressure. The use of fluorocarbon rubber further enhances reliability in demanding environments.

Chemical industry and processing installations

An FKM O-ring is ideal for use in the chemical industry and processing systems. Its resistance to aggressive substances such as acids, bases, fuels and solvents ensures long-lasting performance in extreme conditions. Even at elevated temperatures, the FKM O ring maintains shape and sealing capacity. This makes it a preferred choice where standard elastomers fail to offer the needed protection.

Pharmaceutical and food industry

For direct product contact, a specialized FKM O-ring is often required. Certain FKM compounds meet strict certifications such as FDA, EU 1935/2004, USP Class VI and BfR, making them suitable for pharmaceutical and food applications. These FKM O-rings combine thermal stability, cleanliness and chemical resistance for use in filling equipment, reactors and process piping. The debate between viton vs fkm often comes up in these regulated sectors when choosing the right compound.

Other industrial applications

The FKM O-ring is frequently used in industries where chemical load, speed and temperature extremes occur simultaneously. Applications include pumps, compressors and transmissions where standard materials degrade quickly. With excellent thermal and mechanical properties, the FKM O-ring delivers consistent performance even during long-term exposure to harsh conditions. In such heavy-duty environments, the benefits of o-ring fkm sealing technology become clear.

Advantages of FKM O-rings

The FKM O-ring offers several advantages over traditional elastomers, especially in high-demand industrial settings. It withstands corrosive substances like oils, greases, fuels, acids and solvents while remaining elastic over time. With a temperature range from -20 °C to +200 °C and specialized types for more extreme ranges, the FKM O-ring continues to function even under tough conditions. For regulated industries, certified variants are available. 

Long service life and reliability

The FKM O-ring is praised for its durability and consistent quality in mission-critical systems. It resists permanent deformation, chemical degradation and aging, ensuring long-term sealing performance. Even under heavy exposure to aggressive media, the FKM O ring maintains its flexibility and shape. This is why in continuous-use environments, high-grade viton o rings are often the sealing solution of choice.

Versatility

The FKM O-ring is highly versatile and suitable for both static and dynamic sealing. Thanks to its combination of chemical resistance, heat tolerance and mechanical strength, it performs well across a wide range of industrial scenarios. Whether used in stationary connections or moving components such as shafts and valves, the FKM O-ring delivers reliable sealing even under challenging conditions.

Temperature resistance

The FKM O-ring has an impressive temperature range, staying elastic and reliable between -20 °C and +200 °C. For more demanding applications, special types remain flexible down to -40 °C. Even at elevated temperatures, the FKM O ring maintains sealing performance without deformation or quality loss. This temperature stability makes it suitable for environments with fluctuating or extreme heat exposure.

Suitable for regulated sectors

The FKM O-ring is ideal for use in highly regulated industries such as pharmaceuticals and food processing. Certain compounds meet strict international standards including FDA, EU 1935/2004 and USP Class VI. This allows safe application in direct product contact situations. The FKM O ring combines purity, thermal stability and chemical resistance to meet the strictest requirements. In this context, materials like fluorocarbon rubber provide an added level of reliability and compliance.

Limitations of FKM O-rings

Although O-Ring FKM provides top performance in both chemical and severe thermal environments, unfortunately there are some limitations. First of all, FKM is generally more expensive than standard materials such as NBR. This can play a role in low-budget projects. In addition, O-Ring FKM is not optimal for use with superheated steam or hot wate, as the material can degrade faster. Also, under extreme dynamic loading or prolonged compression, FKM can deform earlier than other elastomers. Finally, its resistance to certain polar solvents such as MEK and ethyl acetate is limited. It is therefore important to consider carefully in each situation whether the FKM O Ring is the right choice of material, especially when steam, specific solvents or mechanical stresses are involved. 

High cost

The FKM O-ring provides excellent performance but comes at a higher price point compared to alternatives like NBR. This is due to its complex composition and premium properties. When extreme resistance is not required, a more economical material may be sufficient. However, in critical applications, the FKM O ring justifies its cost by minimizing downtime and maintenance. In such cases, viton o rings are often chosen for its long-term reliability.

Low steam and hot water resistance

While the FKM O-ring performs well across many industries, it is less effective in applications involving steam or hot water. Especially standard FKM types may deteriorate faster when exposed to superheated steam or high moisture levels. This can lead to accelerated aging and reduced sealing performance. If sealing is needed in steam systems or hot water installations, it is important to review the material’s suitability carefully.

Limited flexibility

Although the FKM O ring performs well in static and lightly dynamic situations, it is not ideal for extreme movement or constant compression loads. In systems with high alternating pressure or continuous motion, the FKM O-ring may lose elasticity or deform more easily. In such cases, choosing a more flexible elastomer may be a better option depending on the application.

Why choose FKM O-rings?

The FKM O-ring is the right choice for environments where high standards are set. These include resistance to aggressive chemicals, thermal stability and long-term durability. Thanks to its tolerance for oils, acids, fuels and solvents, this O-ring offers reliable performance even under harsh conditions. Its wide temperature range from -20 °C to +200 °C (and in special types down to -40 °C) further extends its usability. Additionally, the FKM O ring stays elastic under continuous exposure to UV, ozone and aging. In sectors like chemical, pharmaceutical and food processing, specific versions are available that meet strict regulations such as FDA and EU 1935/2004. When safety, durability and operational reliability are crucial, choosing an FKM O-ring is a smart and dependable decision.