As highlighted by Rubber World in their article “Fluoroelastomers (FKM) for Sealing,” recent advancements in fluorocarbon polymer technology have opened new possibilities for seal designers. Modern fluorocarbons now offer significantly improved resistance to chemicals and temperature, reduced volume swell, and other benefits that make them ideal for extreme sealing conditions. However, careful selection of the appropriate fluorocarbon type for specific sealing applications is crucial.

The fact sheet provided in the article assists in making the right material choice for fluoroelastomers:

A or E Form of FKM: This is one of the oldest and most common elastomers in the FKM product line, with a fluorine content of up to 66%. These types are typically used for standard aerospace specifications and are known for their low compression set. However, they lack resistance to flex fuels containing high levels of alcohol or MTBE, classifying them as general-purpose FKMs.

B Form of FKM: Developed to enhance the fluorine content to 67%, this form offers superior fluid resistance, especially against acids and flex fuels compared to the A or E types. It is specifically used in applications requiring resistance to flex fuels with alcohol or MTBE.

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