Application characteristics of mechanical seal

There are two kinds of seals for vacuum devices. One is that the sealing element separates the container filled with liquid medium from the external vacuum space. In this case, the main function of the seal is to prevent the liquid medium from leaking into the vacuum space. On the other hand, the seal separates the vacuum inner cavity from the outer cavity, and its function is to maintain the required vacuum degree. This situation is more complicated, because even if the surrounding gas medium leaks into the vacuum chamber slightly, its vacuum degree will be reduced. If corrosive gas leaks, the vacuum equipment may be damaged. In many cases, the vacuum degree and the cleanliness of vacuum space have a decisive influence on the quality of various technological processes under vacuum conditions. There is nothing special about the mechanical seal used in vacuum devices. For the first case mentioned above, it is usually a metal corrugated pipe single-ended mechanical seal with good air tightness. In the second case, a double-ended mechanical seal is used. If a single-ended seal is adopted, there is bound to be a problem that the sealing end face cannot be lubricated.

It is difficult to distinguish between mechanical seal and hydraulic seal, and they are often regarded as the same thing.

A, the definition of mechanical seal and hydraulic seal:

Mechanical seal is one of the precise and complicated mechanical basic components, and it is the key component of various pumps, reaction synthesis kettles, turbo compressors, submersible motors and other equipment. Its sealing performance and service life depend on many factors, such as type selection, machine accuracy, correct installation and use.

Hydraulic seal needs pressure, and the joint surface must have a certain smoothness. Seals are mostly made of rubber, and the sealing effect is achieved through local deformation of seals.

Second, the classification of mechanical seal and hydraulic seal

Model of mechanical seal: container seal series, light mechanical seal series, heavy mechanical seal series, etc.

Hydraulic seals: lip seals, V seals, U seals, Y seals, YX seals and hydraulic cylinders. The commonly used combined seals mainly include bud ring, lattice ring and stern seal.

Third, choose the seal.

When purchasing maintenance seals, most users will choose according to the size and color of the samples, which will only increase the difficulty of purchasing and may not be able to choose the right products. The following procedures are recommended to improve the accuracy of purchasing seals:

1. Motion direction-First, determine the motion direction of the seal, such as reciprocating, rotating, screwing in or fixing.

2. Sealing points-for example, the pull rod that determines the moving point is sealed in the inner diameter or the piston that determines the moving point is sealed in the outer diameter.

3. Temperature grade-refer to the operating instructions of the original machinery or evaluate the working temperature according to the actual working environment to determine the required materials. For the description of temperature grade, please refer to the following precautions for production users.

4. Size-Most users will choose and buy according to the used old samples, but after a period of use, the original size of the seal will be greatly affected by factors such as temperature, pressure and wear. According to the sample selection, it can only be used as a reference. A better method is to measure the size of the metal groove where the seal is located, which will have higher accuracy.

5. Pressure grade-refer to the relevant data in the original machine instruction manual, or infer the working pressure grade by observing the hardness and structure of the original seal. For the description of pressure grade, please refer to the following precautions for production users.