FFKM Chemical Compatibility Chart
What perfluoroelastomer really resists, where FKM, EPDM and nitrile give up, and the short list of chemicals that beat FFKM too.
In one line: FFKM resists over 1,600 chemicals, including the acids, amines, ketones, esters, steam and hot caustic that destroy FKM, EPDM and nitrile. The only real exceptions are molten alkali metals, elemental fluorine and a few fluorinated solvents.
Chemical compatibility is where most seal specifications go wrong, because plants rarely handle one fluid. The product is mild, then a solvent flush goes through, then a hot caustic clean, then steam. The seal has to survive all four. Rate the material against the worst step, not the normal one.
Use the table below as a screening tool. It assumes general purpose compounds at moderate temperature and full immersion. Real limits are grade specific, and every 10C rise roughly doubles the rate of chemical attack.
Compatibility by Chemical Family
| Chemical family | FFKM | FKM | EPDM | NBR |
|---|---|---|---|---|
| Acetone, MEK, ketones | Excellent | Poor | Good | Poor |
| Esters, ethyl acetate | Excellent | Poor | Good | Poor |
| Amines | Excellent | Poor | Fair | Poor |
| Steam and hot water | Excellent | Fair | Excellent | Poor |
| Sodium hydroxide, hot caustic | Excellent | Poor | Excellent | Fair |
| Sulphuric acid, concentrated | Excellent | Fair | Poor | Poor |
| Nitric acid | Excellent | Fair | Poor | Poor |
| Hydrochloric acid | Excellent | Good | Good | Fair |
| Hydrofluoric acid | Excellent | Fair | Fair | Poor |
| Aromatic solvents, toluene, xylene | Excellent | Good | Poor | Poor |
| Chlorinated solvents | Excellent | Good | Poor | Poor |
| Mineral oils and fuels | Excellent | Excellent | Poor | Excellent |
| Ethanol, methanol | Excellent | Fair | Good | Good |
| Ethylene oxide, sterilants | Excellent | Fair | Good | Poor |
| Hydrogen peroxide | Excellent | Fair | Good | Poor |
| Ozone and weathering | Excellent | Excellent | Excellent | Poor |
| Molten alkali metals | Not recommended | Not recommended | Not recommended | Not recommended |
| Elemental fluorine | Limited | Not recommended | Not recommended | Not recommended |
Ratings are typical for general purpose compounds at moderate temperature. They are a starting point for discussion, not a specification. Confirm against the compound datasheet and your actual service conditions before ordering.
Four Things a Chart Will Not Tell You
Temperature changes the answer
A fluid rated acceptable at 20C can be marginal at 120C. Give us the peak temperature, including the cleaning cycle, not the average.
Mixtures behave differently
Two fluids that are each harmless can be aggressive together, particularly acid and solvent blends. Rate the mixture, not the components.
Grade matters as much as polymer
Semiconductor, food contact and explosive decompression FFKM grades use different fillers and cure systems, and they do not all resist the same fluids.
Chemistry is only one failure mode
Extrusion, compression set, explosive decompression and installation damage all look like material failure. Upgrading the polymer fixes none of them.
If the failure does not look chemical, work through the seal troubleshooting guide first, and compare the two materials properly on the FFKM vs FKM page.
FFKM Chemical Resistance, Questions Answered
Is FFKM chemically resistant to everything?
Almost, but not quite. FFKM resists over 1,600 industrial chemicals including acids, bases, amines, ketones, esters, steam and most solvents. The known exceptions are molten alkali metals, elemental fluorine, and some fluorinated solvents and refrigerants that can swell certain compounds. Resistance is also grade specific, so a general purpose black FFKM and a semiconductor grade will not behave identically in the same fluid.
Is FFKM resistant to steam?
Yes. FFKM handles saturated steam and sterilise in place cycles that harden FKM within months. This is one of the clearest cases for paying the FFKM premium, especially where steam alternates with solvent or caustic cleaning in the same plant.
Is FFKM resistant to sulphuric acid?
Yes, including hot concentrated sulphuric acid, which destroys most other elastomers. Nitric, hydrochloric, hydrofluoric and phosphoric acid service is also normal FFKM territory. Confirm the temperature and concentration with us, because those two together decide the grade.
Does FFKM resist ketones and esters?
Yes. Acetone, MEK, ethyl acetate and similar solvents swell FKM badly and are a common reason an FKM seal fails within weeks. FFKM is stable in them. If your process has a solvent flush step, that step usually decides the material, not the main product.
Does FFKM resist amines?
Yes. Amine service is a classic FKM killer, producing hardening and cracking. FFKM grades formulated for amines hold up in gas sweetening, pharmaceutical synthesis and coatings work.
Is FFKM resistant to caustic and sodium hydroxide?
Yes, including hot caustic used in clean in place cycles. Strong bases attack many fluoroelastomers by dehydrofluorination. FFKM does not have the same vulnerability, which is why food, dairy and pharmaceutical plants running aggressive CIP move to it.
What chemicals attack FFKM?
Molten or free alkali metals such as sodium and potassium, elemental fluorine and some very aggressive fluorinated fluids. A few refrigerants and fluorinated solvents can cause volume swell in particular compounds. If your fluid is on that short list, tell us and we will look at PTFE, PFA lined or metal sealing options instead of selling you an FFKM that will not last.
How do I read a chemical compatibility chart correctly?
A chart is a screening tool, not a specification. It assumes room temperature, full immersion, and a general purpose compound. Raise the temperature, add pressure cycling, or mix two fluids together and the rating can change. Always confirm the final choice against the specific compound datasheet and the real service conditions.
Does temperature change chemical compatibility?
Substantially. As a working rule, every 10C rise roughly doubles the rate of chemical attack. A fluid rated as acceptable at 20C can be marginal at 120C. That is why we ask for the maximum process temperature and any cleaning cycle temperature before quoting a grade.
Can you check compatibility for my specific fluid?
Yes, and it costs you nothing. Send the fluid or the mixture, the concentration, the maximum temperature, the pressure and the cleaning regime. We will confirm the grade against the compound data and tell you honestly if a cheaper material will do the job.
Send us the fluid, we will confirm the grade
Fluid, concentration, temperature, pressure and cleaning regime. That is all we need to give you a straight answer, including when a cheaper material will do.