Self-energizing o-rings do not require much mechanical preloading which allows O-rings to be used at very high pressures and are offered in a complete range of chemical resistant and general working conditions. NBR, Neoprene,EPDM, FKM etc. are typical materials selected for a variety of service conditions. Teflon is not a good material for an O-ring, particularly when the it is to be dynamic. The encapsulated O-rings.are utilized to gain the chemical resistance offered by Teflon . The encapsulated “O” ring is sensitive to temperature fluctuations so encapsulated O-rings are usually recommended only for static sealing elements
