FKM rubber or Viton is based on hexafluoropropylene vinylidene fluoride. Viton rubber sheet has high resistance to heat with a temperature range of -40 to 250 ℃ it also possesses a good flame resistance and is usually self extinguishing. FKM have excellent resistance to oxygen ,ozone and natural weathering and also have outstanding resistance to compresion especially at elevated temperatures its resistance to most solvents and chemicals give long service life as it has excellent resistance against hydrocarbons ,aliphatics ,aromatic and chlorinated chemicals and resistance to acids and alkalis including oxidants, however ,they have poor performance against ethers ,ketones and bases.