I. Structure of mechanical seal
Mechanical seal is mainly composed of the following four basic components:
Sealing ring: usually made of hard materials (such as carbon graphite, silicon carbide, tungsten carbide, etc.). ), used to bear friction and provide sealing function.
No sealing ring: usually made of flexible materials (such as stainless steel, alloy, etc.). ), which can closely fit the sealing ring and provide sealing support.
Spring: used to provide pressure between sealing ring and non-sealing ring to maintain a good fit.
Auxiliary seal: such as rubber O-ring, wedge ring, etc. Used to seal the gap between the stationary part and the rotating part to prevent fluid leakage.
Second, the working principle of mechanical seal
Mechanical sealing is achieved by the friction pair between sealing ring and non-sealing ring. When the equipment is running, friction occurs between the sealing ring and the non-sealing ring, forming an extremely thin liquid film. The liquid film is composed of leaking fluid, which can effectively prevent the fluid from leaking further.
Liquid film principle: In the working process of mechanical seal, the friction between sealing ring and non-sealing ring will generate heat, so that the leaked fluid will partially evaporate in the gap. The evaporated fluid will form pressure and reduce the leakage rate. At the same time, the heat generated by friction will also reduce the viscosity of the liquid film and further reduce the leakage.
Micro-vibration of sealing surface: during the operation of the equipment, the sealing surface will be subjected to vibration, axial force and radial force, resulting in micro-vibration. These micro-vibrations help to keep the liquid film between sealing surfaces stable and reduce leakage.
Function of spring: the spring provides a certain pre-tightening force for the sealing surface, so that the sealing ring and the non-sealing ring always maintain a good matching state. With the operation of the equipment, friction will lead to the wear of the sealing surface. The spring can automatically adjust the pressure to ensure that the sealing surface always maintains a constant contact force, thus maintaining the sealing effect.
Function of auxiliary seal: auxiliary sealing elements, such as O-rings and wedge-shaped rings, are mainly used to seal the gaps between stationary parts and rotating parts to prevent fluid from leaking from these gaps. The auxiliary seal can also reduce the friction and wear of the sealing surface and improve the sealing effect and service life.
Equipment centering: the sealing effect of mechanical seal is closely related to the degree of equipment centering. If the rotating shaft deviates from the static part of the equipment, it will lead to uneven wear of the sealing surface, thus affecting the sealing effect. Therefore, equipment alignment is an important factor to ensure good sealing performance of mechanical seals.
Third, the application of mechanical seal
Mechanical seals are widely used in various rotating equipment, such as centrifugal pumps, mixers, compressors, blowers, etc. They play an important role in petroleum, chemical, pharmaceutical, food, energy and other fields. The advantages of mechanical seal include high sealing performance, low leakage rate, long service life and simple maintenance, and it is the first choice for sealing devices in these fields.
Four. conclusion
Mechanical seal is an efficient and reliable sealing device, and the sealing effect is achieved by the friction pair between the sealing ring and the non-sealing ring. The working principle of mechanical seal mainly includes the principle of liquid film, the micro-vibration of sealing surface, the role of spring, the role of auxiliary seal and the centering of equipment. Mechanical seals are widely used in various rotating equipment, providing efficient and environmentally friendly sealing solutions for modern industrial and civil systems.