This encapsulated O-Ring consists of an elastomer inner ring and a seamless FEP sheath which surrounds the elastomer ring. It is produced from silicone or fluorocarbon with a seamless FEP jacket. These O-Rings can solve sealing problems due to their chemical resistance coupled with elastic properties and low friction and are therefore used wherever the chemical resistance of normal elastomer O-Rings is insufficient, similar to PFTE O-Rings. FEP encapsulated O-Rings are ideally suited for use in the petrochemical, chemical, medical technology, foodstuff, water and sewage industries, as well as segments with similar functional requirements. Typical applications for FEP encapsulated O-Rings are sealing valve spindles and secondary sealing elements for mechanical seals.

The required elasticity is provided by the elastomer ring, while the chemical resistance is provided by the seamless FEP sheath. FEP is the abbreviated designation for Tetrafluoroethylenehexafluoropropylene copolymer. This material has similar properties to those of Polytetrafluoroethylene (PTFE), with additional benefits of very high chemical resistance and good resistance to abrasion. In contrast to PTFE, however, FEP is thermoplastically moldable. This allows the material to be processed to form flexible semi-finished products, such as thin-walled hoses.

FEP encapsulated O-Rings are used primarily as static seals. They are also suitable for use as sealing elements for slow switching and rotary movements. They are fully interchangeable with standard O-Ring seals. There is no need to modify the groove dimensions. The FEP sheath is relatively thin-walled. (All the specifications given here refer to the installation dimensions of elastomer O-Rings).

Because of the FEP sheath, the O-Rings are less flexible than elastomer O-Rings. They have limited stretch and higher permanent deformation. Split grooves are recommended, especially for outside sealing FEP encapsulated O-Rings, to avoid overstretching during installation. The general information on the construction, design and surfaces given for the elastomer O-Rings also applies to FEP encapsulated O-Rings.

Technical Data:

• Working pressure: Up to 25 MPa (3,626 psi)
• Temperature: -60 °C (-76 °F) up to +200 °C (+392 °F) depending on the elastomer material
• Media: Practically all liquids, gases and chemicals

If you’re interested in purchasing FEP O-Rings or related products, you can visit our O-Ring section.

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