Surface contamination occurs when unwanted material (such as dust or dirt) is found on the surface of a seal (see Figure 172). Surface contamination can largely be eliminated through proper storage and handling of finished seals. Seals exposed to dirty environments (such as work benches) are most susceptible to contamination, especially if the seals have been pre-lubed. The lubrication can pick up and hold on to any grit, metal particles, or dirt the seal might contact.

Foreign material on a shaft seal’s primary sealing lip is a big problem. This foreign material can damage both the lip and the shaft, with leakage likely. Foreign material on other surfaces—such as a secondary lip, at the flex section, on the O.D., or on the endface—can also cause problems.

Care must be taken in choosing a cleaning solution. Depending on the lip material, there are several commonly used solvents (such as high flash napthas or Stoddard solvent). Abrasive and chemical cleaners must not be used; they can irreparably damage the seal elements and/or the bonding.

See Table 49 for a diagram of these seal components.

POSSIBLE MANUFACTURING DEFECTS MAIN PAGE