Polytetrafluoroethylene (PTFE, Teflon) offers superior chemical resistance to oils, solvents, acids and salts. High temperature resistance and low friction are also advantages compared to other elastomers.
With the addition of appropriate fillers, PTFE has excellent mechanical properties, favorable for applications where low lubrication could be a problem.
Fluorocarbon (Viton, Fluorel, Kel-F) elastomers are selected for high underlip temperatures and excellent chemical resistance. Fluorocarbon carries the ASTM designation of FKM and is covered by the ASTM D2000 / SAE J200 - HK classification.
Low temperature resistance is not favorable for dynamic applications. For temperatures below -30°F (-34°C) an alternate elastomer should be selected.
Fluorocarbon elastomers have good resistance to the swelling and deteriorating effects of aromatic solvents, aliphatic hydrocarbons, halogenated hydrocarbons such as carbon tetrachloride, trichloroethylene, diester oils, silicate ester oils, petroleum oils, and many mineral acids. They are also highly recommended in applications involving ozone combined with heat, as in electric motors and electrical equipment.
Fluorocarbons are not recommended for use with highly polar fluids such as hydrazine, ketones, phosphate esters like Skydrol, anhydrous ammonia, low-molecular- weight esters and hot hydrofluoric or chlorosufonic acids.
Polyacrylate elastomers are most commonly selected for higher operating temperatures or extreme pressure (EP) lubricants. Polyacrylate carries the ASTM designation ACM and is covered by the ASTM D2000 / SAE J200 - DF, DH or EH classification.
The main advantage Polyacrylate has over Nitriles is a higher temperature range and additional resistance to ozone and weather attack.
It is not compatible with glycol based brake fluids, aromates, chlorinated hydrocarbons, hot water / steam, acids, alkalis, amines and is not to be used in dry running applications.