Common sealing forms of chemical pumps
There are various sealing forms for chemical pumps, each of which has its specific application scenarios and advantages and disadvantages. The following are several common sealing forms for chemical pumps:
1. Mechanical seal
Features: Mechanical seal is the most widely used sealing form in the chemical pump industry. It has the advantages of low leakage and long service life, and is an important shaft sealing method in chemical pumps and other equipment in the world today. Mechanical seals are devices that prevent fluid leakage by maintaining contact and relative sliding under the action of fluid pressure and the elastic force (or magnetic force) of the compensation mechanism and the cooperation of auxiliary seals.
Application: Suitable for chemical pumps under various working conditions, especially those that require long-term continuous operation and strict leakage requirements.
2. Gasket seal
Features: Gaskets are the basic components of static seals for centrifugal pumps and have a very wide range of uses. The selection of gaskets is mainly determined by factors such as the conveying medium, temperature, pressure and corrosiveness of the chemical pump. Gasket seals achieve sealing by plastic deformation of the gasket material under the action of the compression load to fill the tiny unevenness of the flange sealing surface.
Application: Suitable for static sealing occasions of various chemical pumps, such as the seal between the pump body and the flange.
3. Packing seal
Features: Packing seal is to put the packing with high compressibility and resilience into the stuffing box, and rely on the axial pressure of the gland to convert it into radial sealing force, so as to play a sealing role. This sealing method has a simple structure, easy replacement, low price, and strong adaptability to speed, pressure and medium.
Application: It is widely used in the design of chemical pumps, especially in the occasions where the medium contains solid particles or the packing needs to be replaced frequently.
4. Thread seal
Features: On chemical pumps, thread seals generally have two forms: one is threaded connection gasket seal, and the other is thread plus filler seal. Both are used for sealing occasions with small diameter thread connections. The thread only provides the role of compression, and the sealing effect is mainly achieved by the gasket or filler.
Application: Suitable for sealing occasions of chemical pumps with small diameter thread connections.
5. Oil seal
Features: The oil seal is a self-tightening lip seal with a simple structure, small size, low cost, easy maintenance, and small resistance torque. It can prevent medium leakage and external dust and other harmful substances from invading. However, oil seals are not resistant to high pressure, so they are generally used in chemical pumps in low-pressure situations.
Application: Suitable for chemical pumps with low pressure, low speed and low sealing requirements.
6. Labyrinth seal
Features: Labyrinth seals have good sealing effects when they are reasonably designed, well processed, well assembled and have high speed. However, in actual applications, chemical pumps leak more because the processing and assembly accuracy is difficult to guarantee, so they are not commonly used in chemical pump seals.
Application: Although it is not commonly used, it can still be considered for use under certain specific conditions (such as high speed and low leakage requirements).
7. Dynamic seal
Features: Dynamic seals include various forms such as spiral seals. When the chemical pump is running, the pressure head generated by the auxiliary impeller balances the high-pressure liquid at the outlet of the main impeller, thereby achieving sealing. The auxiliary impeller does not work when the pump is stopped, so a parking seal must be equipped at the same time to solve the possible leakage of the chemical pump when the pump is stopped. The dynamic seal has a simple structure, reliable sealing and a long service life.
Application: Suitable for chemical pumps that transport media containing impurities, especially where leakage-free operation is required.
