Mechanical seal application characteristics

There are two situations for the sealing of vacuum devices. One is that the seal separates a 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. Another situation is that the seal separates the vacuum inner cavity from the outer cavity, and its function is to maintain the required vacuum. This situation is more complicated, because even a slight leakage of the surrounding gaseous medium into the vacuum chamber will reduce its vacuum. If corrosive gas leaks in, the vacuum equipment may be damaged. In many cases, the degree of vacuum and the cleanliness of the vacuum space have a decisive influence on the quality of various processes carried out under vacuum conditions.　The mechanical seal used in the vacuum device has no special features in its structure. For the first case mentioned above, a metal bellows type single-end mechanical seal with good airtightness is usually used. In the second case, a double end face mechanical seal is used. If a single end face seal is used, there is bound to be a problem that the seal end face cannot be lubricated.
Generally, it is difficult for people to distinguish between mechanical seals and hydraulic seals.


Definition of mechanical seals and hydraulic seals:

Mechanical seals are one of the basic mechanical components with precision and complex structure. They are key components 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, etc.
Hydraulic seals have pressure requirements and require a certain degree of smoothness on the joint surface. The sealing elements are mostly rubber, and the sealing effect is achieved through the local deformation of the seal.


Classification of mechanical seals and hydraulic seals：

Mechanical seal model: cartridge seal series, light mechanical seal series, heavy mechanical seal series, etc.
Hydraulic seals: lip seals, V-shaped seals, U-shaped seals, Y-shaped seals, YX-shaped seals, and hydraulic cylinders. The commonly used combined seals are mainly lace rings, grid rings and ster seals.

Choose the seal：

When purchasing seals for maintenance, most users will buy them according to the size and color of the samples. This will only increase the difficulty of purchasing and may not necessarily be able to select the right product. The following procedures are recommended to improve the accuracy of procurement of seals:

1. The direction of movement-first determine the direction of movement of the location of the seal, such as reciprocating, rotating, spiral or fixed.
2. Sealing focus-for example, determine whether the active point is the tie rod seal with the inner diameter or the piston seal with the outer diameter.
3. Temperature grade-consult the original machinery operating instructions or evaluate the working temperature according to the actual working environment to determine the materials needed. For the description of the temperature level, please refer to the following notes for production users.
4. Size-most users will choose the old samples that have been used, but after a period of use, the original size of the seal will be greatly affected by factors such as temperature, pressure and wear. The selection according to the sample can only be used as a reference , A better method is to measure the size of the metal groove where the seal is located, the accuracy will be higher.
5. Pressure level-refer to the relevant data from the original mechanical instructions, or infer the working pressure level by observing the hardness and structure of the original seal. For the pressure level description, please refer to the following notes for production users.