Elastomer compatibility: FKM vs EPDM vs FFKM
No generic chart. The temperature ranges below plus the real failure modes we see — because most early seal failures we encounter trace back to the elastomer, not the seal size.
Standard elastomer operating ranges
Ranges describe the elastomer material family, not a complete assembly rating. Final operating limits depend on the full seal configuration and are confirmed during technical review.
| Elastomer Family | Lower Temp Limit | Upper Temp Limit | Chemical Resistance Profile |
|---|---|---|---|
| FKM (Fluorocarbon) | -20°C | +200°C | Excellent resistance to mineral oils, synthetic fluids, and aliphatic hydrocarbons. |
| FFKM (Perfluoroelastomer) | -15°C | +315°C | Broadest chemical resistance across almost all aggressive acids, bases, ketones, and solvents. |
| EPDM (Ethylene Propylene) | -40°C | +150°C | Excellent for steam, water, ketones, and dilute acids. Avoid use with petroleum oils. |
| PTFE (Polytetrafluoroethylene) | -100°C | +250°C | Virtually inert to all process chemicals. Used in high-corrosion chemical environments. |
Failure mode 1: FKM that swells in amine
A brochure says “chemical resistant” — but which chemical, at what temperature? FKM rated for oils can swell and soften in amines or strong bases. When the O-ring swells, it extrudes, nicks, and the seal starts weeping within weeks. Always name the actual medium, not the industry.
Failure mode 2: EPDM that degrades in oil
EPDM is superb in steam and water — and destroyed by petroleum oils. A water-service seal moved to an oily duty without an elastomer change will swell shut. This is the classic “but it worked on the other pump” failure: same seal, different medium, different elastomer required.
Failure mode 3: FFKM where PTFE would do
Over-specifying has a cost of its own. FFKM covers nearly everything, but where PTFE suits the duty it is the simpler, proven choice for corrosive service. Tell us the medium and temperature and we map the elastomer at the intersection — Pressure ∩ Temperature ∩ Media ∩ Speed — instead of guessing from a compatibility chart alone.
Check your duty with us
Send the medium, temperature, and pressure — we confirm the elastomer and face pairing before quoting. Our RFQ checklist shows exactly what to include.