Apple Rubber offers a wide range of Fluoroelastomer (FKM or FS) compounds for many industrial applications and environments. FKM is highly valued for its superior resistance to heat, oils, fuels, and many chemicals. However, it is not a universal solution for every sealing challenge, so choosing the wrong compound can cause failure in critical systems.
Sometimes FKM is not the right choice for your application. FKM may work in the short term, but other polymers may be required to meet long-term reliability requirements for sealing components. To make the right selection, carefully weigh factors such as specific chemical exposure, extreme operating temperature, and increased regulatory restrictions against application needs.
We recommend working closely with our design engineers to select the most effective material for your operation. Consider the following three primary reasons FKM may not suit your application.
- Amine-based Preservatives and Additives
Amine-based preservatives and additives are used in new high-performance lubricants to extend lubricating oil life. Their primary function is antioxidant protection and corrosion resistance. Amines help neutralize free radicals and reduce acidic degradation, but they attack standard FKM polymers by dehydrohalogenation. This reaction strips hydrogen fluoride from the polymer backbone, creating reactive sites that can lead to uncontrolled crosslinking or chain scission. End users may see the rubber become brittle or lose elongation. Amines are commonly found in automatic transmission fluid. Better options would be HNBR or polyacrylates.
- Poor Low-temperature Performance:
Standard FKM grades are typically rated only to -25°C (-13ºF). Specify the correct FKM formulation if your application requires low-temperature performance. FKM polymers like Viton GLT™ or Viton GFLT™ from Chemours can be used for static applications down to -40°C (-40ºF). New higher-performance polymers can reach -60°C (-76ºF) for static applications. These polymers are significantly more costly and may still face functionality issues in dynamic situations as they harden near their glass transition temperature.
- PFAS Free:
When PFAS regulations are uncertain, using other polymers where possible can reduce future regulatory work. For higher temperatures, peroxide-cured HNBR can handle 175ºC (347ºF) and still provide very good fuel and oil resistance. Peroxide-cured EPDM can handle some acid environments.
For more information or help selecting the right compound, please get in touch with Apple Rubber.