FKM vs. Kalrez

Attribute	FKM	Kalrez
Chemical Resistance	Good	Excellent
Temperature Resistance	Good	Excellent
Compression Set	Good	Excellent
Cost	Lower	Higher

Introduction

When it comes to choosing the right material for sealing applications, two popular options that often come up are FKM (fluoroelastomer) and Kalrez (perfluoroelastomer). Both materials are known for their excellent chemical resistance and high temperature capabilities, making them ideal choices for demanding environments. In this article, we will compare the attributes of FKM and Kalrez to help you make an informed decision for your specific application.

Chemical Resistance

One of the key factors to consider when choosing a sealing material is its chemical resistance. FKM is known for its resistance to a wide range of chemicals, including oils, fuels, and acids. It can withstand exposure to harsh chemicals without deteriorating, making it a popular choice for applications in the automotive and aerospace industries. On the other hand, Kalrez offers even greater chemical resistance, particularly in extreme environments where FKM may not be sufficient. Kalrez is resistant to a broader range of chemicals, including more aggressive acids and solvents, making it the preferred choice for critical applications where failure is not an option.

Temperature Resistance

Another important attribute to consider is the temperature resistance of the sealing material. FKM has a temperature range of -20°C to 200°C, making it suitable for a wide range of applications. It can withstand high temperatures without losing its sealing properties, making it a reliable choice for many industries. Kalrez, on the other hand, has a much higher temperature range of -20°C to 325°C, making it ideal for applications where extreme heat is a concern. Kalrez can maintain its integrity and sealing performance at higher temperatures, providing a level of reliability that FKM may not be able to match.

Compression Set

Compression set refers to the ability of a material to maintain its shape and sealing properties after being compressed over time. FKM has a low compression set, meaning it can maintain a tight seal even after prolonged use. This makes it a durable choice for applications where consistent sealing performance is crucial. Kalrez, on the other hand, has an even lower compression set than FKM, ensuring that it can maintain its sealing properties over a longer period of time. This makes Kalrez the preferred choice for applications where reliability and longevity are paramount.

Cost

Cost is always a factor to consider when choosing a sealing material for your application. FKM is generally more cost-effective than Kalrez, making it a popular choice for applications where budget constraints are a concern. While FKM offers excellent performance at a lower cost, Kalrez provides superior performance at a higher price point. The decision between FKM and Kalrez may ultimately come down to the specific requirements of your application and whether the added performance of Kalrez justifies the higher cost.

Conclusion

In conclusion, both FKM and Kalrez are excellent choices for sealing applications that require high chemical resistance, temperature resistance, and compression set. FKM offers good performance at a lower cost, while Kalrez provides superior performance in extreme environments at a higher price point. When choosing between FKM and Kalrez, it is important to consider the specific requirements of your application and weigh the benefits of each material against your budget constraints. Ultimately, the right choice will depend on finding the balance between performance, cost, and reliability for your specific sealing application.