Known for high media and temperature resistance, Perfluoroelastomers or FFKM has a wide range of chemical stability for use where extreme safety standards are required and where high maintenance and repair costs exceed the costs of quality seals. FFKM materials are elastomeric compounds designed with high fluorine content to offer extreme chemical resistance, similar to PTFE, and also offer rubbery-elastic qualities of an elastomer with flexibility and resilience. 

The chemical resistance prevents the molecular breakdown of the rubber. The resilience and spring back allow for continued sealing during thermal changes and joint movement. Dupont was the first to offer this solution with their Kalrez product line. Since then, other competitors including Parker, Freudenberg, and Minnesota Rubber introduced FFKM O-Rings to their product lines.

Advantages of FFKM

  • Wide temperature range (-55°C – 330°C)
  • Excellent chemical resistance – Resists over 1,800 different chemicals
  • Good mechanical properties, maintains seal integrity
  • Excellent gas and liquid permeation resistance
  • Excellent weather ability and ozone resistance
  • Self-extinguishing and non-flammable in air
  • Reduces maintenance and operating costs
  • Meets safety standards for pharmaceutical and food processing

Disadvantages of FFKM

  • Can swell significantly in fluorinated solvents
  • Should not be used with molten or gaseous alkali metals
  • Thermal coefficient larger than other elastomers, so seal housing size may need modifying
  • High cost, so generally used when no other elastomer is appropriate

FFKM materials are found in markets such as chemical, industrial, oil and gas, semiconductor, food & pharmaceutical, medical, and aerospace applications. These industries often have critical sealing applications where high-end elastomers prevent costly downtime and provide safe seals to prevent exposure to strong chemicals and high temperatures. In many cases, specific formulations of FFKM are created depending on the industry’s needs. Specific formulations depend on the industry’s need in a specific process.

Within the Semiconductor industry, there are specific FFKM compounds depending on whether the need is for Plasma Etch, Thermal Oxidation and Diffusion, or Wet Etching processes. These compounds are designed as pure as possible. Any impurity will result in defective integrated microchips. Some of these processes involve strong acids so chemical resistance is important. Equipment downtime can result in massive production costs so going with a premium elastomer is nothing compared to knowing the part will work the first time and last longer than lower-performing alternatives.

Within the Chemical Industry, there are specific formulations available that are designed for optimal temperature and compression set resistance. In other cases, steam and strong chemical resistance have been prioritized. Most of these properties far exceed any other rubber elastomer solution available on the market today.

Within the Food and Drug Administration, there are compounds designed for compliance with USP Class VI and FDA regulation 21 CFR 177.2600 which meet low extractable compatibility.

Kalrez 7075 has the highest temperature rating of any elastomer solution available. It also offers the greatest compression set resistance and strong acid resistance in addition to the high-temperature capability.

Kalrez 4079 is an industry-standard, particularly with a new AMS formulation for the aerospace market. It offers high temperature and compression set resistance. Kalrez 4079AMS offers high thermo-oxidative stability in gas turbine engines and meets the requirements of AMS 7257.

It is so important to understand all needs of the seal regardless of the industry, so the best compound can be selected. Sharing as much of this information with Sealing Devices Applications Engineers will result in the best product selection in the shortest amount of time.

Let us know if there are ways we can improve your seals today to save money down the road.