Overview
PFAS restriction has moved from a chemicals question to a design question. The proposal filed with the European Chemicals Agency in 2023 by five member states covers fluoropolymers and fluoroelastomers as a class, and while the final scope and any derogations are still open, procurement organizations are already asking suppliers to declare fluorine content and identify replacements. If a seal in your assembly is FKM, FFKM, or AFLAS, it falls inside the definitions currently being used.
That puts most engineers in one of two positions. Either you need to know what is actually in the part you already buy, or you need to know what a compound without fluorine would cost you in performance. Both are answerable, and the second one is where a molder that compounds and tests in-house is worth more than a distributor.
What we can test
Our ISO/IEC 17025:2017 accredited laboratory characterizes elastomers by physical and thermal property, and those results are what a substitution decision turns on. We do not run trace-level analytical chemistry for PFAS quantitation, that is a specialist analytical service and we will say so plainly rather than imply a capability we do not hold. What we do run, and run to an accredited method, is the performance comparison.
- Identification of fluorine-containing families in a compound from formulation records and supplier documentation, for compounds we make
- Full physical property characterization of an incumbent fluoroelastomer, so a candidate has a measured target to hit instead of a datasheet number
- Heat aging to ASTM D573 and compression set to ASTM D395 on both incumbent and candidate, at your service temperature
- Fluid immersion to ASTM D471 in your actual media, which is where most substitutions fail
- Low-temperature behavior, the property non-fluorinated candidates most often lose on
What a replacement gives up
There is no drop-in for a fluoroelastomer. Anything that matches FKM on chemical breadth and 200 °C continuous service, at a comparable sealing force and price, contains fluorine. The practical question is narrower: on the specific duty your part actually sees, how much of the fluoroelastomer's envelope are you using?
Parts specified in FKM because a datasheet said 200 °C, but running at 130 °C in hot water or steam, are frequently better served by a well-developed HNBR, which has no fluorine, costs substantially less, and beats FKM outright in hot water. Parts in genuinely aggressive fuels or aromatic solvents at temperature are not. Peroxide-cured EPDM covers steam and hot water but nothing hydrocarbon. Silicone covers temperature extremes but not fluids or wear.
| Candidate | ASTM | Fluorine | Where it can replace a fluoroelastomer |
|---|---|---|---|
| Hydrogenated Nitrile | HNBR | None | Hot water and steam sealing, oil and refrigerant service to about 150 °C |
| EPDM, peroxide cured | EPDM | None | Steam, hot water, weathering, dilute acids and bases. No hydrocarbon service |
| Silicone | VMQ | None | Wide temperature range, biocompatible and food-contact duty. Poor in fuels |
| Epichlorohydrin | CO/ECO | None | Fuel and oil service where cold flexibility matters and 175 °C is not required |
| AFLAS | FEPM | Contains fluorine | Steam, amines and strong bases where FKM degrades. Still inside PFAS definitions |
Note that AFLAS is on that list as a technical alternative to FKM, not as a PFAS-free one. It is a fluoroelastomer and it is captured by the same proposals. Any program treating fluorine removal as the requirement has to look at the four families above it.
How a substitution program runs here
The work is a compound development project with a test plan attached. We characterize the incumbent, agree the property window that actually matters for the part, develop and mold candidates, and age them in your media at your temperature until something either holds or does not. Molding the candidate on the same presses that will make production parts removes a variable most substitution programs never close.
If nothing non-fluorinated holds, get that result in writing. A derogation request or an internal exemption is built on it, and it costs less to produce before a line goes down than after.