Fluoroelastomer is a broad classification covering two similar base elastomers: Viton* and Fluorel**. Compounds from either elastomer can be formulated to withstand temperatures up to +600°F for limited periods but become fairly stiff when subjected to -20°F. Service temperatures are generally limited to these two values. Although extremely stiff at -85°F, Fluoroelastomer compounds are not brittle at this temperature. Outstanding resistance to aromatic fuels and straight aromatic as well as halogenated hydrocarbons has opened many new applications for these compounds. The materials can be compounded to achieve good resistance to strong acids, including RFNA.