FEP/PFA encapsulated O-rings

FEP/PFA encapsulated O-rings consist of an elastomer (FKM or VMQ) inner ring and a seamless FEP/PFA sheath which surrounds the elastomer ring.

The FEP sheath is relatively thin-walled, it is possible to install the O-ring in the existing grooves, there is no need to modify the groove dimensions.

Advantages

• Low friction, no adhesion or stick-slip effect
• Very good chemical resistance and compatible with most chemicals
• Physiologically safe, can be sterilized and can be used with foodstuffs, pharmaceuticals and medicinal products
• Temperature application range from approximately -60°C (-76°F) up to 200°C (392°F), depending on the material of the inner ring.

Sealing effect

The encapsulated O-rings are double acting sealing elements. The sheath serves to seal while the O-ring acts as a resilient pre-tightening clamping element. They are mainly used as static seals (axial and radial). For dynamic sealing, the FEP O-rings for slow switching and rotary movements are suitable.

• Encapsulated O-rings are available in following standard sizes: A S568A
• Metric units of cross-section: 2 - 2,5 - 3 - 3,5 - 4 - 5 - 6 - 7 - 8 mm, etc
• Swedish standards of cross-section: 1,6 – 2,4 – 3 – 5,7 – 8,4 mm

Assembly instructions

The same recommendations apply to the installation of encapsulated O-rings as for standard elastomer O-rings. Some specific points should however be noted:

• The encapsulated O-Ring should on no account be stretched or bent
• The sharp edges should be avoided, or must be covered
• The FEP or PFA sheaths are not flexible, they have limited stretch: this implies that Installation in closed grooves is not advised and even forbidden for a d1<20 mm.

In the case of an installation in closed grooves, we recommend to heat the seal between 70°C and 150°C in water or oil and grease the parts in contact with the seal.

These installation recommendations are only indications and are intended as approximate guidelines. Users are advised to perform tests validating the installation.