Overview of vacuum system and knowledge

The definition of vacuum

The meaning of vacuum refers to a condition of being below one atmosphere of pressure in a given space. People usually refer to this thin gaseous state as a vacuum condition, and the vast space between the Earth and planets is vacuum. The general term for vacuum refers to relative vacuum, and absolute vacuum is almost non-existent, even at the lowest pressure that can be achieved, there are still a few gas molecules per cubic meter of gas. Vacuum technology refers to the technology of making the gas pressure lower than the atmospheric pressure on the ground, which is usually achieved by special vacuum pumps. Vacuum has many uses in science and technology, electron vacuum instruments, vacuum tubes and other electronic instruments.

Vacuum system

   What is a vacuum system? In a nutshell, it is a system designed to obtain a specific vacuum degree according to the requirements of the container to be evacuated. The basic content of vacuum system design includes selecting an appropriate vacuum system design scheme based on the vacuum degree requirements of the container to be evacuated, calculating the selection of pumps (determining the pipes, valves, traps, and vacuum measurement elements), and rationally configuring them. Finally, draw the assembly diagram and component diagram of the vacuum system.
There are many types of vacuum application equipment, but whatever type of vacuum application equipment there is, there is always a system for removing the gas in the evacuated container in order to obtain the desired vacuum conditions in the vacuum container. For example: a container for vacuum treatment, connected to a vacuum pump by pipes and valves, needs a vacuum measurement device when the vacuum pump evacuates the container. This constitutes the simplest vacuum pumping system (as shown in Figure 1). A more complete vacuum system consists of the following components: 1. Vacuum pumping equipment, such as various types of vacuum pumps; 2. Vacuum valves; 3. Connecting pipes; 4. Vacuum measurement devices, such as vacuum pressure gauges and various types of manometers; 5. Other components, such as collectors, dust filters, vacuum interlock switches, and storage tanks.

Vacuum measurement and unit conversion

   In vacuum technology, "vacuum degree" and "pressure" are generally used to express the degree of vacuum. The lower the pressure in a certain space, the higher the vacuum degree; the higher the pressure, the lower the vacuum degree. In addition to the pressure unit Pa of the International System of Units, Torr (Torr) or millibar (mbar) is often used as the unit of vacuum degree, 1 Torr equals the pressure generated by a 1 millimeter high column of mercury, i.e., 1Torr=133.3224Pa; kPa and MPa are also used in engineering; in addition, there are units such as bar, mmHg, atm, kg/cm2, and PSI. The common conversion relationships between vacuum degree units are shown in Table 1.

Based on the different physical characteristics in each pressure range, vacuum is generally divided into several regions: rough vacuum, low vacuum, medium vacuum, high vacuum, ultra-high vacuum, and extremely high vacuum.

Vacuum of moderate degree: 105 to 103 Pa

Low vacuum: 103-10^-1 Pa

High vacuum: 10^-1 Pa to 10^-6 Pa

Ultra-high vacuum: 10^-6 Pa to 10^-10 Pa

Extremely high vacuum: less than 10^-10 Pa