FKM Flourocarbon Rubber - Viton©
Fluoroelastomer copolymer FKMs are composed of vinylidene fluoride and hexafluoropropylene
They show excellent overall performance with an operating temperature range of -20°C to 200°C.
Benefits of FKM Flourocarbon Rubber - Viton©
They exhibit resistance to a broader range of chemicals combined with very good high temperature properties more so than any of the other elastomers. They are known especially for their non-flammability, low gas permeability and excellent resistance to ozone, weathering and aging.
Depending on structure and fluorine content FKM compounds can differ with regards to their chemical resistance and cold-flexibility. When exposed to low temperatures, fluorocarbon elastomers can become quite hard (-4 °F) but can be serviceable at low temperatures, although FKM compounds are not recommended for applications requiring good low temperature flexibility.
In addition to standard FKM materials, a number of special materials are available with differing monomer compositions and fluorine content (65% to 71%) for improved low temperature, high temperature, or chemical resistance performance.
Fluorocarbons are highly resistant to swelling when exposed to fuel as well as resistant to degradation due to expose to UV light and ozone. Fluorocarbons exhibit low gas permeability making them well suited for hard vacuum service and many formulations are self-extinguishing.
FKM compounds are not generally recommended for exposure to hot water, steam, polar solvents, low molecular weight esters and ethers, glycol based brake fluids, or hot hydrofluoric or chlorosulfonic acids.
The operating temperatures of the Fluorocarbon Rubber range between -20 °C /-4 °F and +200 °C /+392 °F (for a short period of time up to +230 °C /+446 °F). Suitable formulated FKM can be used down to -35 °C /-31 °F.
FKM is also often used with mineral based oils and greases at high temperatures. It offers a wide range of chemical compatibility, and excellent temperature range, low compression set and impermeability including excellent aging characteristics.
FKM is generally used as a liner and combined with ECO or VMQ for hose construction. In this way you benefit from the excellent chemical resistance properties without the cost of building the entire hose from FKM.