A description of the types

Sealing is a crucial factor in most aspects of our daily lives within our homes and vehicles. Among the hundreds of seals in the average vehicle, modern turbocharged engines include at least one seal that is required to carry out a similar duty to those of interest in this paper; that is, separating the engine air flow from bearing oil. Also in the oil and gas industry, or in a petrochemical processing plant, there are many pumps and compressors with seals that closely resemble those used in gas turbine engines on aircraft. A key factor with any installation is that the seals impede the progress of fluid. The key word is impede (i.e., to delay or prevent), because just about every known seal, including static gaskets, will leak (Fig. 1) [1]. For high integrity static seals it may be an extremely small amount, so small that we call it an “emission” rather than a leak. But even one millilitre per year is still leakage [2]. clearance in the seal, otherwise rapid wear will occur. Contacting types of rotary seals without lubrication are only used either for slow speed or very short life applications.