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Mechanical Seals for Pump
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Mechanical Seals for Pump

Mechanical seal for pump is a kind of dynamic seal assembly, which is widely used on the rotating shaft. It is also known as the end seal. Consisting of at least a pair of end faces which are perpendicular to the rotating shaft, mechanical seal acts on the end surface through fluid pressure and compensation mechanism (elastic force or magnetic force). In addition, auxiliary seal makes the joint surface stick and keep relative sliding, so as to prevent fluid leakage.

The working principle of mechanical seal for pump is to form the thin liquid film between rotating ring and shaft, so that it can efficiently prevent leakage of medium and make the end face lubricated, which help achieve the sealing effect. Mechanical seals are often used in rotating machinery, such as pumps, compressors, and reaction stirred kettle.
There are 2 common sealing methods of the pump: mechanical seal and soft packing seal. Each of them has different characteristics and they are also suitable for different occasions. The correct selection of mechanical seals is beneficial to reducing the cost and improving the working efficiency. 

Compared with the soft packing seal, the mechanical seal for pump has the following advantages:

  • Good sealing function. In the long working, the sealing state of mechanical seals for pump is very stable, and the leakage is small: about 1% of the leakage of soft packing seal. 
  • Long service life. The general service life can reach more than 1~2 year when used in oil and water working occasions; and the mechanical seals should have 6-months service life when used in chemical medium.
  • Small consumption of friction power. The friction power of mechanical seals for pump is only 10% ~ 50% of the soft packing seal. And the abrasion of the shaft or sleeve can be negligible.
  • Long maintenance period. The mechanical seals for pump can still meet the requirements of usage, even thought its end face is in a certain range of repair.
  • Good earthquake resistance. It is not sensitive to the vibration of the rotating shaft.
Of course, compared with the soft packing seal, mechanical seals for pump have complex structure, higher requirements and cost. And the operators needs to have a certain level of technology, such as the basic knowledge of fitter and the characteristics of the mechanical seal.