FFKM (Perfluoroelastomer) O-rings
-20 °C to 260 °C
FFKM is an ultra-premium perfluoroelastomer (known as Kalrez®, Chemraz®) with the highest chemical and temperature resistance among elastomers. Used in the most demanding applications.
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Temperature and chemical compatibility
Temperature and chemical compatibility
Temperature range: -20 °C to +260 °C (short-term up to +325 °C).
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Typical applications: semiconductor industry, plasma processes, aggressive chemicals, pharmaceutical reactors, aerospace, sterilization processes.
FFKM (Perfluoroelastomer)
Each elastomer has different mechanical and chemical properties.
FFKM (Perfluoroelastomer) — properties and applications
FFKM (perfluoroelastomer) is the most resistant — and at the same time the most expensive — elastomer you'd commonly use for O-rings today; its price runs to tens of times that of NBR. In return it offers almost universal chemical resistance and handles extreme temperatures. FFKM O-rings work in the −20 to +260 °C range (briefly up to +325 °C) and their typical hardness is 75 ShA, so they cover even operations in which other materials fail. On the market you'll also know it under the brand names Kalrez® and Chemraz®.
When it comes to media, FFKM is among the most universal choices: it shows good to excellent resistance across oils, fuels, acids, bases, amines, solvents and steam alike. It's precisely this breadth of resistance that's the reason it's reached for where aggressive chemicals combine with high temperature and where no cheaper elastomer reliably lasts. Where FKM (Viton®) runs up against strong bases, amines or extreme temperature, FFKM is still sealing.
The only real limitation of FFKM is its price, not its technical properties — which is why it isn't deployed across the board, but in a targeted way wherever it's justified. For ordinary oil, fuel and water applications it's overpriced and you'll get by with NBR, EPDM or FKM. When choosing a specific FFKM compound, what's more, the manufacturer type and purity class matter (for semiconductor processes, for example), so we select a suitable compound according to the application.
Typical uses are found in semiconductor manufacturing, in pharmaceuticals and in the chemical industry — wherever a seal has to survive what other materials can't withstand. In the material hierarchy FFKM stands right at the top: above FKM in both performance and price. An FFKM O-ring is the last-resort choice for the most demanding combinations of medium and temperature — choose it when you have an aggressive medium and a high temperature at the same time and no other material gives you the certainty that the seal will hold.
Browse all O-rings across every material.
O-ring material comparison
Indicative values for a quick comparison. Temperature ranges are conservative (continuous service); for a specific medium always verify compatibility or consult a technician.
| Material | Temperature range | Mineral oil | Water | Acid | Fuel | Hardness (Sh A) | Relative price (vs NBR) |
|---|---|---|---|---|---|---|---|
| NBR | -30 – 100 °C | Excellent | Limited | Avoid | Excellent | 70 Sh A | 1.0× |
| HNBR | -30 – 150 °C | Excellent | Limited | Avoid | Excellent | 75 Sh A | 3.0× |
| FKM | -20 – 200 °C | Excellent | Limited | Excellent | Excellent | 75 Sh A | 5.0× |
| FFKM — your selection | -20 – 260 °C | Excellent | Excellent | Excellent | Excellent | 75 Sh A | 50.0× |
| EPDM | -40 – 130 °C | Unsafe | Excellent | Excellent | Unsafe | 70 Sh A | 1.2× |
| VMQ | -60 – 200 °C | Avoid | Excellent | Avoid | Avoid | 70 Sh A | 3.5× |
| PU | -40 – 80 °C | Excellent | Limited | Avoid | Limited | 90 Sh A | 2.0× |