Seal Selection

Mechanical Seal Selection There are many factors that govern the selection of seals. These factors apply to any type of seal ... 

These factors are not necessarily all the guide-points in final seal selection, as individual conditions may be so special or unusual as to justify a special design or a compounding of the features of several standard designs. Only rarely will any seal be perfect for the service or job application. Many types and designs of seals are available, each to fill a certain need. Table 12-7 lists a few for general applications. 

Breeding habits vary from species to species, with some true seals selecting one mate, while others opt for mating with more than one female during a breeding season. Phocids are excellent divers, and many can swim to great depths, but this ability varies from species to species. Weddell seals can reach depths of 1,968.5 feet (600 m) and stay underwater for more than an hour. 

The factor of percent compliance to contamination control targets aggregates the organization s performance in various aspects of contamination control. This includes new oil management and dispensing practices, filter selection and maintenance, breather selection and maintenance, seal selection and maintenance, proper combustion management, and other aspects of effective contamination control. If the machine is not in conformance, one or more of the above named (or other) sources of contamination requires attention. 

In those vessels requiring sealing, two common types of seal are employed packed-gland units and mechanical seals. Selection is usually dictated by application. The cheaper, packed-gland type are often used for low-pressure vessels, whilst at high pressures mechanical seals are preferred. However, when vessel contents are the main consideration, mechanical seals are employed when hazardous materials are under mix, whereas for less hazardous liquors a packed gland is normal. 

TABLE 9.22. Caustic Pumping Applications and Seal Selection... 

While proper seal selection and installation are critical, consideration must also be given to proper hole forming. Holes through poured concrete walls can be saw cut or formed with steel or thermoplastic sleeves. If saw-cut, there must not be any voids in the footprint of the installed seal, and the penetration must be free of dust and dirt. The modular seal can then be installed directly into the penetration. 

The stack assembly procedure also affects the seal selection process. For instance, a laminate structure of anode, electrolytes, and cathode is formed by the plasma spraying technique. The microstructuring processing steps must be controlled so that the interfacial reactions and interdiffusion between those layers can... 

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