Definition of Mechanical Seal

Mechanical seal is an oil seal device for rotating machinery. Such as centrifugal pumps, centrifuges, reactors and compressors and other equipment. Since the drive shaft runs through the inside and outside of the equipment, there is a circumferential gap between the shaft and the equipment, through which the medium in the equipment leaks out. If the pressure in the equipment is lower than atmospheric pressure, the air leaks into the equipment, so there must be a Shaft seals to prevent leaks.

There are many types of shaft seals. Since mechanical seals have the advantages of less leakage and long service life, mechanical seals are the main shaft sealing methods in these equipment. Mechanical seals, also known as end face seals, are defined in the relevant standards as follows: 'At least one pair of end faces perpendicular to the axis of rotation are kept in contact with each other under the action of fluid pressure and the elastic force (or magnetic force) of the compensation mechanism and the cooperation of the auxiliary seal. Sliding device to prevent fluid leakage.

” What are the requirements for the sealing ring of the mechanical seal? The sealing ring is the general term of the dynamic ring and the static ring (the same below), and is the main component of the mechanical seal. The sealing ring determines the use of the mechanical seal to a large extent. Performance and longevity, therefore, put some demands on it.

1. There is enough strength and stiffness. It is not damaged under working conditions (such as pressure, temperature and sliding speed, etc.), the deformation should be as small as possible, and the sealing can still be maintained when the working conditions fluctuate.

2. The sealing end face should have sufficient hardness and corrosion resistance to ensure a satisfactory service life under working conditions.

3. The sealing ring should have good thermal shock resistance. For this reason, the material is required to have a high thermal conductivity and a small coefficient of linear expansion, so that it will not crack when subjected to thermal shock.

4. The matching of the sealing ring should have a small friction coefficient and good self-lubrication, and the material of the sealing ring should have good wettability with the sealing fluid. If dry friction occurs for a short time during work, the sealing end face will not be damaged.

5. The sealing ring should be simple, symmetrical and give priority to the use of an integral structure. Combination type (such as insert type) sealing ring can also be used, try to avoid spraying type structure with sealing end face.

6. The sealing ring should be easy to manufacture, easy to install and maintain, and low in price.