Designing a shaft seal and selecting the materials that will function well in a given environment are far from simple tasks. Even experienced seal designers are often met with unusual service requirements that test both their ingenuity and the capabilities of the seal. Whether your sealing needs are simple or complex, the factors to be considered are numerous enough to guarantee that not every seal will be successful in every application.

When shaft seals do leak, you can often determine why through careful inspection of all elements within the sealing system. This includes not only the seal, but also the shaft (or other running surface) and the housing bore. An examination of the lubricant should also be conducted. All of these elements should be studied both with the failed seal in place and following its removal.

RMA CHECKLISTS
In order to facilitate this inspection process, the Rubber Manufacturers Association (RMA) developed a series of four checklists. As shown in Table 68, the first of these is designed to step you through examination of the sealing system and its environment prior to seal removal.

As shown in Table 69, the second checklist steps you through an examination of the seal following removal.

As shown in Table 70, the third checklist steps you through an examination of the housing bore, the shaft, and the lubricant in use following seal removal.

Because the use of these three checklists in their entirety may not be practical in field situations, the RMA also developed a shortened form designed to expedite inspection. That short form is shown in Table 71.