Perfluoroelastomer (FFKM)

What is FFKM?

FFKM (perfluoroelastomer) is a highly fluorinated FKM, with fluorine levels at or above 73%. It has a fully fluorinated backbone chain with a prevalence of carbon-fluorine bonds giving exceptional levels of chemical and thermal resistance, better than any other elastomer. Similiar resistance properties to that of PTFE, but with elastomeric properties similiar to an FKM.  

When to use FFKM

FFKM seals carry an enhanced initial procurement cost compared to most other elastomers, so their use is naturally limited to applications in aggressive environments where no other elastomer will survive the temperature or chemical conditions for long enough (for example in the manufacture of semiconductors), or in applications where downtime and costs associated with a seal replacement would outweigh the high procurement cost of the seal (for example in the oil and gas extraction and processing industries). They can provide a more practical and cost effective elastomeric seal solution in applications where either a PTFE or metallic seal would have been the usual selection.  

Whilst the chemical compatibility of FFKM materials can be considered near universal, it is still important to select the optimum grade for the specific application. Applications involving fluorinated refrigerants and perfluorinated lubricants (PFPE) may be unsuitable even for FFKM. Temperature capability typically covers -15°C (+5°F) to +260°C (+500°F) with special grades available down to -25°C (-13°F) or up to +325°C (617°F). The high coefficient of thermal expansion of FFKM materials may require specific hardware designs in high temperature applications to ensure groove overfill is avoided.