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When searching for a chemical resistant
o-ring, gasket, or seal, the most successful elastomers will be in the class of fluorocarbon
rubbers. Several characteristics of fluorocarbon rubber tend to
impart the characteristics necessary for chemical resistance,
specifically,
- the ratio of fluorine to hydrogen,
- the inherent strength of the carbon-fluorine bond,
- the absence of carbon bond unsaturation, and
- the steric hindrance associated with fluorinated structures.
As a general rule, the higher the fluorine content, the broader the
chemical resistance. However, there are exceptions to this rule that can
be attributable to the solubility parameter
of a given reagent and the elastomer designated to seal the reagent. Consideration
must also be given to the curative employed within the fluorocarbon
rubber.
The second rule of thumb is that the higher the fluorine content, the
more expensive the polymer will be. But again, exceptions exist. For
instance, a Type 2 FKM (such as Viton ® B) possesses a higher Fluorine content than an
Aflas
® FEPM, yet the FKM costs less. Generally speaking, FKM's will be the least
expensive fluorocarbon elastomer, followed by FEPM, with the most expensive being
FFKM.
Good background information on Fluorocarbon
Elastomers can be found in our Technical
Papers Online page. For information on base resistance you may want
to visit our statement about BREs.
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Seals Eastern, Inc.,
is an engineering and manufacturing firm,
founded in 1960, with the resources to design, manufacture, and deliver high
quality elastomer seals, gaskets, and
o-rings for the most demanding
seal applications throughout the world.
Click here to learn more about Seals Eastern
To learn more about AFLAS
®
To
learn more about Viton ®
AFLAS® is a registered trademark of the Asahi Glass Company.
Viton® is a registered trademark of Dupont Dow Elastomers, LLC.
Fluorel® is a registered trademark of Dyneon, LLC.
OringOnline® is a registered trademark of Seals Eastern, Inc.
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