RT/Dygert also offers a wide array of metric sizes, in both standard and non-standard dimensions. As a subset of the metric sizes offered, we also stock many Japanese Industrial Standard (JIS B2401) sizes. If an O-ring with special size or fluid resistance is required, RT/Dygert can provide custom O-rings, specially made to your demanding requirements.
FEP PFA Encapsulated O-Ring
Teflon® Encapsulated O-Rings combine the resilience and sealing force of an elastomer with the chemical resistance of Teflon®. They consist of an elastomeric core of Silicone or Viton® with a relatively thin, molded encapsulation of Teflon® FEP or PFA polymer. This produces an elastomeric PTFE seal with maximum sealing capability. FEP Encapsulated O-Rings are solvent resistant and chemically inert (except for attack by alkaline metals, fluorine and some halogenated compounds at high temperatures) yet they have an elastomeric memory near that of rubber O-rings. FEP polymer also has an extremely low coefficient of friction (.1 to .2) and very low permeability to gases, making the Encapsulated O-Ring a virtually universal seal for use in hostile environments. PFA offers improved mechanical and creep properties at elevated temperatures (up to 500°F)
See the Silicone or Viton® materials section for their temperature and chemical resistance properties.