Water Vapor Transmission: Teflon® encapsulated O-ring
All plastics have some permeability to gases. In the case of the FEP/PFA encapsulation of the ENCAP-O-SEAL, Teflon® encapsulated O-ring, gases and vapors will permeate at a considerably lower rate than for most other plastics. Water vapor transmission rates are an important benchmark for determining core material choice when specifying an encapsulated o-ring for extreme applications. See How to choose Application Specific Encapsulated O-rings.