According to different working conditions and medium properties, mechanical seals include high-temperature and low-temperature resistant mechanical seals, high-pressure and corrosion resistant mechanical seals, granular media resistant mechanical seals, and light hydrocarbon media that are easy to vaporize. Mechanical seals with different structural types and materials shall be selected according to different uses of centrifugal pumps.

The main parameters of model selection include: pressure of sealing chamber (MPa), fluid temperature (℃), working speed (m/s), fluid characteristics and effective space for installing seals.

1. According to the temperature and fluid properties, determine the friction pairs and auxiliary sealing materials, and correctly select the lubrication, flushing, thermal insulation, cooling and other mechanical seal circulation protection systems.

2. According to the pressure of the sealing chamber, it is determined that the sealing structure is balanced or unbalanced, single end or double end.

3. According to the effective space of the installation seal, it is determined to use multiple springs or single springs or wave springs, internal or external.

4. Rotary or static, hydrodynamic or non-contact type shall be adopted according to the working speed.