Sealing principles

Seals, which may be individual sealing elements or combinations of parts arranged to interact, are intended to prevent substances from escaping from an enclosed space into adjoining spaces. the object is to prevent, as far as possible, changes in pressure and temperature and the invasion of foreign substances

Widely varying sealing duties have to be performed in chemical plants. Equipment closures, connections, and piping systems usually employ static or stationary seals. But in many cases it is necessary to seal rotating parts, as in the case of agitators, pumps, compressors, and piping accessories. Anyone wishing to seal rotating parts economically usually has to put up with a certain amount of leakage. These seals are categorized under the heading of dynamic sealing.

Magnetic drives have to be considered separately. Because the energy is transmitted by a magnetic field, hermetic static sealing of the rotating shaft is possible.

Dynamic agitator seals for hermetic sealing are very widespread, especially where a single product is processed in large quantities. Here the availability and effectiveness of individual system components that operate without any back-up in the event of failure.

Dynamic contact seals on rotating shafts can be divided into two general groups, which differ essentially in the direction of the contact forces, see Fig. 1.