Fluoroelastomer, FKM, FPM, Viton®... the name alone, whose commercial reference has become more common than the official name, is already a mess, so we have decided to write a small didactic guide on this material that is so common in our markets:
First, let's bring some order to the nomenclature:
FluoroelastomerFluorocarbon rubber: a synthetic rubber based on fluorocarbon compounds containing carbon-fluorine bonds.
FPMEuropean designation according to DIN/ISO 1629.
FKMAmerican designation according to ASTM D1418.
Vitonis a registered trademark of Chemours.
Aflas®is a registered trademark of Asahi.
Fluorelis a registered trademark of Dyneon, a division of 3M Company.
Main characteristics:
- Thermal stability, even above 200 ºC.
- Wide chemical resistance (strong acids, fuels, greases...).
- Longer service life.
- Low gas permeability.
FPM offers an excellent combination of mechanical properties that are sought after in a rubber, such as chemical inertness and thermal resistance.
Varieties
The FKM cited in most chemical resistance tables (including ours) refers to type 1 FKM, cured with Bisphenol, the closest to the original compound. However, peroxide cured polymers are more suitable in alkaline environments or in contact with water and high temperature steam. At the other end of the table, we find Viton Extreme® (ETP) or FEPM fluoroelastomer according to ASTM. It presents the particularity of being resistant in highly alkaline solutions, steam and amines, but it is relatively little known in the market, due to its difficult processing.
Variants
Articles made of FKM can be supplied with a wide variety of options or certificates: lubrication, PTFE coating, conductive, AED, USP, 3A, FDA, CE1935/2004, KTW, NSF, detectable and in all colors (brown and black being the most common).