Seals star with aggressive media

An independent comparison of different FFKM materials has revealed significant differences between the various elastomers.

Seals made of perfluoroelastomer (FFKM) are resistant to extreme temperatures and a broad range of chemicals.

These high-end sealing materials are used in applications where other elastomers have failed.

O-rings made of the new FFKM material Simriz 495 are universally applicable because of their outstanding resistance to chemicals.

Moreover, the fact that they can be used across a broad application temperature range from -15 to +260C guarantees optimum reliability.

An independent comparison of different FFKM materials revealed significant differences between the various elastomers: 10 of the 14 FFKM seals tested broke down when used with critical media - not so the one made of Simriz 495.

The decisive advantage of perfluorinated elastomer O-ring seals over pure PTFE seals is their elastic properties.

With a fluorination level of 76%, PTFE has the highest known level of media resistance.

However, their lack of elasticity means that PTFE seals can only be used in applications characterised by permanent positive engagement.

FFKM O-rings, on the other hand, have a fluorination level of approximately 72% percent similar media resistance to PTFE.

However, they are also outstandingly elastic, which is important for long-term imperviousness.

Freudenberg has been working on the continuous optimisation of FFKM for many years.

The latest innovation is the O-ring material Simriz 495.

This FFKM elastomer can be used over an unusually broad application temperature range.

Simriz 495 O-rings provide reliable, long-term sealing from -15 to +260C.

They can also be subjected to temperatures up to +300C for short periods.

FFKM's high chemical resistance varies greatly depending on the elastomer mix and the way in which it is processed.

In order to define Simriz 495's universal media resistance clearly, an accredited test institute was commissioned with the comparison of O-rings made of 14 different FFKM elastomers.

FFKM O-rings for general applications in the chemical industry, those with incredibly high temperature resistance and those that meet the requirements of the FDA were used for the tests.

Among other things, the following properties were tested: compression set in accordance with DIN ISO815 over 72 hours in air, water and steam at 200C, and the change in volume and hardness after 72 hours (DIN53521) in various media at different temperatures.

The comparison showed that only four FFKM O-rings could be used without restrictions for all media groups.

One of these materials was Simriz 495 with its outstanding source values.

In terms of change in hardness, Simriz 495 turned out to be the best in the test.

No fewer than 10 of the 14 FFKM elastomer O-rings broke down when used with critical media.

Not so Simriz 495, which offers broad chemical resistance and proved resistant not only to alcohols, alkalis and ketones, but also to acids and amines at boiling point temperatures.

In short, Simriz 495 is one of the truly universal FFKM sealing materials.

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