What is the principle of vacuum pump

The principle of the vacuum pump is mainly based on reducing or eliminating the gas molecules in the closed container by mechanical or physical means, thereby reducing the pressure in the container to achieve the purpose of generating a vacuum. The following is a detailed explanation of the principle of the vacuum pump:

1. Basic principle
The vacuum pump uses a mechanical device to change the volume in the pump chamber to extract, compress and discharge the gas. During the suction process, the volume of the pump chamber increases, forming a local low-pressure area, so that the gas in the container is sucked into the pump; during the compression process, the volume of the pump chamber gradually decreases, the gas is compressed and accumulates energy; finally, during the exhaust process, the high-pressure gas is discharged from the pump through the exhaust valve to complete a working cycle.

2. Working principles of different types of vacuum pumps
Positive displacement vacuum pump:
Definition: The suction, compression and discharge of gas are achieved by changing the volume of the pump chamber.
Mechanical parts: usually include one or more pistons, screws or rotary impellers, etc.
Working process: During the suction stage, the volume of the pump chamber increases, forming a local low-pressure area, and the gas is sucked in; during the compression stage, the volume of the pump chamber decreases, and the gas is compressed; during the exhaust stage, the high-pressure gas is discharged through the exhaust valve.
Advantages: It can provide a high vacuum degree and a large gas flow rate, and is suitable for occasions that require rapid extraction or large amounts of gas processing.
Disadvantages: High noise, high energy consumption, and relatively high maintenance costs.
Molecular vacuum pump:
Definition: Extracting gas by physical means (such as the collision of gas molecules with high-speed rotating parts).
Mechanical parts: Usually contain one or more high-speed rotating rotors or centrifuges.
Working process: When the rotor or centrifuge rotates, gas molecules will continuously hit its surface and be carried away, thereby achieving gas extraction.
Advantages: It can provide a very stable vacuum degree and a small gas reflux, and is suitable for occasions that require high vacuum and have high requirements for gas purity.
Disadvantages: The flow rate is relatively small, and the applicable pressure range is also relatively limited.

3. Specific examples
Taking the spiral blade pump as an example, its working principle is to randomly arrange several spiral blades with the cylindrical wall of the pump. The drive part of the pump rotates the cylinder, and the spiral blades suck the gas from the inlet. While discharging gas, the spiral blades form a one-way gas flow path on the surface of the pump cylinder to ensure the continuity and flow of the gas extraction.

4. Application of vacuum pumps
Vacuum pumps have been widely used in many fields due to their unique vacuum extraction capabilities. For example, in the metallurgical industry, vacuum pumps are used for vacuum degassing and vacuum refining in the metal smelting process; in the chemical industry, vacuum pumps are used to create a vacuum environment for chemical reactions and separate and purify products; in the food industry, vacuum pumps are used for vacuum packaging of food to extend the shelf life.

In summary, the principle of the vacuum pump is mainly based on mechanically or physically changing the volume in the pump chamber to extract, compress and discharge gas. Different types of vacuum pumps differ in structure and working principle, but all have the function of extracting gas. When choosing a vacuum pump, you need to choose a suitable pump type according to the specific application scenario and needs.