The following profiles of the most commonly used shaft seal polymers are intended to serve as general guidelines only. Inherent strengths and weaknesses are noted, but keep in mind that these properties may be enhanced or diminished through compounding. For this reason, selecting the best material for a given application will inevitably require both comparison and compromise. When possible, you should always test the final formulation (the base polymer and all additional modifying agents) in actual service conditions prior to field use. Table 4 shows the color coding for the individual atoms depicted in the molecular illustrations of each polymer. Table 9 shows a summary of base polymer properties. Table 10 shows the results of life tests on shaft seals with the same design and size but with lips molded from different polymer types.

NITRILE (NBR)
HYDROGENATED NITRILE (HNBR)
FLUOROELASTOMER (FKM)
POLYACRYLATE (ACM)
SILICONE (VMQ)
POLYTETRAFLUOROETHYLENE (FEP/PTFE)

“Selecting the best material for a given application will inevitably require both comparison and compromise.”

Table 4

Table 9

Table 10