Tip: FEP/PFA Encapsulated O-ring Part 2

(This tip is about the characteristics the inner elastomer core brings to the o-ring)

Keep in mind that just as the outer jacket of FEP or PFA in the FEP/PFA encapsulated o-ring brings certain advantages to the o-ring, the inner elastomer core also brings its own desirable characteristics. That doubles the advantages you can get from this one o-ring.

Here at PSP we find that most of our customers prefer a Viton® core. Because of the low compression set of Viton®, it is a good fit for most applications. If the application requires extremely high or low temperatures then another elastomer needs to be chosen.

An encapsulated o-ring with silicone as the core works very well for a very low temperature applications. If low loading is also a requirement, then a hollow core can be used, it compresses easier than a solid silicone core.

In spite of the fact that FEP/PFA encapsulated o-rings offer so many advantages, there are times when you would not want to use them.

Abrasion
FEP and PFA do not wear well in abrasive materials whether they are liquid, powder or a slurry. The wall of the jacket is thin and simply will not stand up to any kind of abrasive materials.

Dynamic Situations
FEP and PFA do not stand up well in a dynamic environment even in situations with low speed and excellent finishes on the surface of the mating parts.

Collapsing
If you try to squeeze the encapsulated o-ring into a bore it can be severely damaged because the jacket will kink.

Stretching
Just as FEP and PFA cannot be compressed, it also will not survive extreme stretching. They will crack and the elastomer core of Viton® or silicone may also break.

Please call us if you need help in choosing a FEP/PFA encapsulated o-ring for your application. Our engineers are happy to talk about all the details of your application so you can make a wise choice.