FFKM is the wrong choice when the failure is not caused by elastomer compatibility, or when a lower cost material has been proven for the whole duty. If the leak comes from pump condition, groove geometry, installation, loss of flush or an unexamined duty, do not buy another seal yet.
Start with the evidence from the failed seal and the equipment. Check the faces, secondary seals, shaft movement, groove condition, squeeze, surface finish and any flush or barrier system. Record when the leak begins and what changed before deciding that the elastomer needs upgrading.
FFKM is a family of compounds, not a universal answer. Resistance to steam, amines and bases varies by grade, cure system and formulation. Check the maker’s data for the exact grade against the actual product plus every CIP and SIP chemical, including concentration, maximum temperature, exposure time and number of cycles.
Compliance is compound specific too. A declaration or test result for one FFKM compound does not automatically cover another grade, and a compliance statement does not prove that the material will survive the process or cleaning duty.
Cost is a valid reason to choose EPDM, FKM or another material only when that exact compound is proven for the complete operating and cleaning cycle. The cheapest suitable material is a sound engineering choice. The cheapest material family named without grade specific evidence is not.
Sometimes the answer is not a different elastomer. Dry running, solids at the faces, repeated pressure reversal, extrusion gaps, movement or loss of lubrication can require a revised groove, harder back up arrangement, different face materials, a flush or barrier system, or a different seal design. Andrew’s independent verdict is simple: diagnose the duty and failure first, then specify the material and sealing arrangement together.
Andrew Sykes, independent mechanical seals and sealing specialist.