Kalrez^® Seals: Key Properties, Applications, and Alternatives

High-performance sealing materials play a critical role in industries where equipment reliability, chemical resistance, and thermal stability determine overall productivity. Among the various elastomer families used today, perfluoroelastomers (FFKM) stand out as the highest grade of sealing materials. As manufacturing processes become more advanced and process chemicals more demanding, the need for dependable FFKM solutions continues to grow.

Within this category, Kalrez^® has become one of the most widely referenced names, and it is commonly used as a benchmark when engineers evaluate sealing performance requirements. Many companies turn to Kalrez^® specifications when establishing material standards for semiconductor tools, chemical reactors, pharmaceutical systems, and other critical equipment.

However, with increasing demand in industries such as semiconductors, energy, biotechnology, and advanced manufacturing, the role of FFKM materials continues to expand. While Kalrez^® remains one of the most established names, many companies are also exploring second source FFKM solutions that provide similar reliability at a more cost-effective level. Katon contributes to this growing field by offering engineered FFKM compounds that align with application requirements where Kalrez^® materials are traditionally used.

What Is Kalrez^®?

Kalrez^® is a perfluoroelastomer (FFKM) brand, and is recognized as one of the highest performing sealing materials available today. It was originally developed by DuPont, the company that pioneered FFKM technology and introduced the first commercially available FFKM compound to the market. This innovation allowed industries operating in highly corrosive and high-temperature environments to achieve levels of sealing reliability previously unattainable with traditional elastomers.

Today, Kalrez^® is part of the QNITY portfolio, and it continues to serve as a leading reference point for FFKM technology. The brand is known for its consistency, long-term performance, and broad compatibility with critical process environments. As a result, engineers often use Kalrez^® specifications as a starting point when evaluating FFKM materials for new equipment designs or when qualifying alternative compounds.

Core Features and Material Advantages

Kalrez^® represents one of the earliest and most widely referenced implementations of perfluoroelastomer (FFKM) technology. Many of its performance characteristics reflect the broader advantages associated with FFKM materials as a class, which are now produced by multiple manufacturers worldwide.

A key advantage of FFKM materials, including Kalrez^® and Katon^® FFKM, is their exceptional resistance to aggressive chemicals. Fully fluorinated elastomer structures allow resistance to strong mineral acids, organic solvents, amines, and hydrocarbons, reducing the risk of swelling, chemical attack, or premature degradation in corrosive environments. FFKM materials are valued for combining rubber-like elasticity with chemical resistance approaching that of PTFE. This balance allows seals to conform to hardware tolerances while resisting some of the harshest processing chemistries used in advanced manufacturing environments.

High temperature capability is another defining characteristic of FFKM compounds. Depending on formulation, many FFKM grades can operate continuously at temperatures approaching 300°C or higher. This thermal stability supports use in semiconductor chambers, chemical reactors, and energy systems where prolonged heat exposure is unavoidable.

Typical Applications

Semiconductor Manufacturing

In semiconductor fabrication, FFKM seals are used in equipment that operates under high temperatures, vacuum conditions, and chemically aggressive environments. These processes require sealing materials with low outgassing, strong plasma resistance, and minimal particle generation in order to maintain yield and process consistency.

Chemical Processing

Chemical processing facilities rely on FFKM seals in pumps, valves, mechanical seals, reactors, and transfer systems. These components are frequently exposed to strong acids, solvents, hydrocarbons, and mixed chemical streams. FFKM materials help maintain dimensional stability and sealing integrity under continuous chemical exposure and elevated operating temperatures, reducing the risk of leakage and unplanned maintenance.

Pharmaceutical and Biotechnology

In pharmaceutical and biotechnology manufacturing, FFKM materials are used in systems that undergo repeated cleaning and sterilization cycles. Applications include process equipment exposed to CIP and SIP procedures involving steam, hot water, and aggressive cleaning agents. Seals in these environments must resist both chemical attack and thermal cycling while supporting contamination control and regulatory compliance.

Oil, Gas, and Energy

FFKM seals are applied in oil and gas exploration, refining, and energy production equipment where high temperatures, corrosive media, and pressure fluctuations are common. These processes are often exposed to hydrocarbons, sour gas, amines, and rapid gas decompression conditions. In these environments, special grade FFKM’s play a critical role in preventing seal failure and ensuring operational safety.

Popular Kalrez^® Grades and Their Alternatives

Over the years, Kalrez^® has introduced multiple FFKM grades tailored to different operating environments, including chemical processing, high-temperature sealing, semiconductor manufacturing, and oil and gas applications. These grades are often used as reference points when engineers evaluate sealing materials. As the FFKM market has matured, equivalent compounds from other manufacturers have been developed to meet similar performance requirements. Katon offers several FFKM materials designed to align with the functional intent of commonly specified Kalrez^® grades.

Kalrez^® 6375 and Katon^® 8075B

One of the most common Kalrez^® compounds, Kalrez^® 6375 is widely used for applications requiring broad chemical resistance, particularly in environments involving strong acids and corrosive process media. It has a maximum service temperature of 275°C (527°F), and it is commonly found in semiconductor wet processes and chemical processing equipment where consistent performance across multiple chemicals is required.

Katon^® 8075B is designed for similar service conditions with a slighty higher maximum service temperature of 290°C (554°F), offering strong resistance to acids, alkalis, solvents, fuels, and aggressive gases. It also performs reliably in steam and hot water environments, making it suitable for chemical processing systems. For users seeking broad chemical compatibility with stable long-term performance, Katon 8075B is often evaluated as an alternative to Kalrez^® 6375.

Kalrez^® 4079 and Katon^® 9080B

Another common Kalrez^® compound is Kalrez^® 4079, known for its high-temperature stability and low compression set, with a maximum service temperature of 316°C (600°F). Making it suitable for sealing applications exposed to sustained heat and thermal cycling.

Katon^® 9080B is engineered with a similar focus on thermal stability and resistance to temperature cycling. With a maximum service temperature of 317°C (602°F), it supports demanding high-temperature applications in chemical processing and industrial systems.

Both compounds are not recommended where hot water or certain hot amines are present.

Kalrez^® 7075 and Katon 9175B

Kalrez^® 7075 builds upon the performance characteristics of 4079 by offering an enhanced compression set and higher service temperature of 327°C (620°F), while maintaining broad chemical resistance. It is commonly selected for chemical processing applications that require long-term sealing reliability under heat and pressure.

Katon^® 9175B is developed with similar performance to Kalrez^® 7075. It supports continuous operation up to approximately 325°C (617°F) while maintaining mechanical integrity during temperature and pressure cycling. This makes Katon 9175B suitable for chemical processing, petroleum refining, and mechanical sealing systems where Kalrez^® 7075 is often specified.

Kalrez^® 9100 and Katon^® 8075C

Kalrez^® 9100 is formulated for semiconductor applications that demand plasma resistance, low outgassing, and tight contamination control. It is commonly used in dry semiconductor processes where low metal contamination is crucial.

Katon^® 8075C is engineered specifically for advanced semiconductor environments, featuring very low metallic content and strong plasma resistance. Its formulation supports low particle generation and stable performance in dry process chemistries.

Kalrez^® 0090 and Katon^® 7990B

Kalrez^® 0090 is designed for oil and gas applications, particularly where resistance to rapid gas decompression and sour gas exposure is required. It is often specified for high-pressure sealing environments involving H₂S and amines.

Katon^® 7990B is a high-hardness FFKM developed for oil and gas service conditions. It is engineered to withstand rapid gas decompression, extreme pressure, and sour gas exposure while maintaining sealing integrity. For upstream and energy applications where RGD performance is critical.

Conclusion

Kalrez^® is widely recognized as the original inventor of FFKM technology and remains a premium reference brand for sealing performance in extreme chemical and thermal environments. Its long-standing use across critical industries has helped define performance standards for perfluoroelastomer materials.

As FFKM technology has advanced, equivalent materials are now available that deliver comparable reliability and durability. Katon offers engineered FFKM alternatives designed to meet the same application requirements while providing greater cost efficiency. This allows companies to maintain high sealing performance without relying exclusively on premium-priced materials.