Leakage In Mechanical Seals


The definition of seal leakage falls into two categories:

  • Visible leakage. You can see liquid or vapors coming from the seal.
  • The leakage allowed by fugitive emission laws. (Usually defined in parts per million).

Just about any good balanced O-ring seal can run without visible leakage as evidenced by the mechanical seal in the water pump of your automobile, or the fact that an automobile air conditioning compressor can hold a Freon charge for several years.

Fugitive emission sealing is another problem.

There are some stationary single seals that can seal well enough to pass a fugitive emission test, but most of the older rotating seal designs cannot. Dual seals operating with either gas or liquid barrier fluid between the seals are the most popular solution to fugitive emission sealing.

See “dual seals” for more information on this subject.