Vacuum pumping methods

Mechanical pump vacuum pumping, diffusion pump vacuum pumping, molecular pump vacuum pumping, and cryogenic pump vacuum pumping are four commonly used vacuum pumping methods.

They each have unique working principles, application scenarios, and advantages and disadvantages. In practical applications, we need to choose the appropriate vacuum extraction method based on specific needs and conditions.

For example, in situations where high pumping speed and low vacuum degree are required, we can choose mechanical pumps to evacuate;

For situations that require extremely high vacuum and good extraction efficiency for specific gases, we can choose diffusion pumps or cryogenic pumps for vacuum extraction;

For situations that require both high vacuum and high pumping speed, we can choose molecular pumps for vacuum pumping.

By selecting and applying these vacuum extraction methods reasonably, we can effectively meet various scientific research, production, and experimental needs, and promote the progress and development of science and technology. 

Below are detailed explanations of these four methods of vacuuming.

一、Mechanical pump vacuum pumping

Mechanical pumping is the most traditional and common method of vacuuming. It mainly relies on mechanical force (such as rotation or reciprocating motion) to generate suction, thereby extracting gas from the container or space and achieving the goal of reducing pressure.

Working principle

Mechanical pumps typically consist of one or more rotors rotating within the pump body, which suck in and discharge gas through the rotational motion of the rotors. When the rotor rotates, it forms a low-pressure area inside the pump body, which attracts gas from the container or space into the pump body, and is then carried by the rotor to the high-pressure area and discharged outside the pump.

Application

Mechanical pump vacuum pumping is widely used in scientific research, medical treatment, industry and other fields. For example, in the laboratory, mechanical pumps are often used to extract gases from containers such as reaction vessels and distillation bottles; In the medical field, it is used to extract air from medication bottles and syringes; In industrial production, mechanical pumps are often used to extract gas from large containers or pipelines.

Advantages and disadvantages

Advantages: simple structure, easy operation, and low maintenance cost.

Disadvantages: relatively slow pumping speed, poor adaptability to certain specific gases (such as corrosive gases), and the generation of certain noise and vibration during operation, which may affect some precision experiments or production environments. 

二、Diffusion pump vacuum pumping

Diffusion pump vacuum pumping is a method of vacuum pumping that utilizes the principle of gas molecule diffusion. It mainly relies on the diffusion motion of gas molecules between high and low pressure regions to achieve vacuum pumping.

Working principle

The diffusion pump consists of a heated diffusion chamber and a cooled collection chamber. When the diffusion chamber is heated, the gas molecules inside will gain sufficient energy and diffuse outwards. Due to the pressure difference between the diffusion chamber and the collection chamber, gas molecules tend to diffuse towards the collection chamber. In the collection room, gas molecules are cooled and condensed into liquids or solids, thereby achieving vacuum pumping.

Application

Diffusion pump vacuum pumping has a wide range of applications in scientific research and high-tech fields.

For example, in the fields of semiconductor manufacturing, optical instrument manufacturing, vacuum coating, etc., diffusion pumps are often used to extract high vacuum environments.

In addition, in scientific research experiments, diffusion pumps are also an important choice when obtaining extremely high vacuum levels. 

Advantages and disadvantages

Advantages: Able to achieve extremely high vacuum levels; very effective in extracting certain gases such as hydrogen, oxygen, etc.

Disadvantages: Complex structure, high operation and maintenance costs; The heating and cooling process requires a large amount of energy consumption;; When working, it is also necessary to pay attention to preventing the entry of pollutants such as oil vapor, otherwise it will affect the vacuum pumping effect. 

三、Molecular pump vacuum pumping

Molecular pump vacuum pumping is a method of using a high-speed rotating rotor to transport gas molecules from the inlet to the outlet and discharge them outside the pump. It mainly relies on the interaction between gas molecules and the rotor surface to achieve vacuum pumping.

Working principle

A molecular pump consists of a high-speed rotating rotor and a fixed stator. When the rotor rotates, it forms a high-speed airflow channel inside the pump body. When gas molecules pass through this channel, they will collide with the rotor surface and be carried to the outlet and discharged outside the pump. Due to the high-speed rotation of the rotor, the residence time of gas molecules in the pump body is very short, thereby achieving efficient vacuum pumping.

Application

Molecular pump vacuum pumping has a wide range of applications in situations where high vacuum degree and high pumping speed are required. For example, in fields such as semiconductor manufacturing, vacuum coating, and space simulation experiments, molecular pumps are often used to extract high vacuum environments. In addition, in scientific research experiments, molecular pumps are also an important choice when both high vacuum and high pumping speed requirements need to be met simultaneously.

Advantages and disadvantages

Advantages: It can achieve high vacuum degree and high pumping speed, and has excellent extraction effect for most gases.

Disadvantages: Complex structure; The manufacturing cost is relatively high; Regular maintenance is required; During work, it is also necessary to pay attention to preventing the entry of pollutants such as particulate matter, otherwise it will affect the vacuum pumping effect and lifespan. 

四、Vacuum pumping by cryogenic pump

Vacuum pumping with a cryogenic pump is a method of vacuuming using the principle of low-temperature condensation. It mainly relies on the condensation and adsorption of gas molecules at low temperatures to achieve vacuum pumping.

Working principle

A cryogenic pump consists of a cooling system and an adsorption system. When the cooling system is working, it will lower the temperature inside the pump body to an extremely low level (usually below -100 ℃). At this temperature, most gas molecules lose their activity and condense into solids or liquids. Subsequently, these condensed gas molecules will be adsorbed by the adsorption system and remain in the pump body, thereby achieving vacuum pumping.

Application

Cryopump vacuum extraction has a wide range of applications in situations that require extremely high vacuum levels and extremely low temperature environments. For example, in the fields of superconducting material research, low-temperature physics experiments, space science, etc., cryopumps are often used to extract extremely high vacuum environments. In addition, in scientific research experiments, when it is necessary to simultaneously meet the requirements of high vacuum and low temperature environment, a cryogenic pump is also an important choice.

Advantages and disadvantages

Advantages: It can achieve extremely high vacuum degree and extremely low temperature environment, and has very good extraction effect for most gases.

Disadvantages: Complex structure; Both manufacturing and usage costs are relatively high; Professional maintenance and operation are required; During work, it is also necessary to pay attention to preventing the entry of pollutants such as water vapor, otherwise it will affect the vacuum pumping effect and service life; Due to its low-temperature characteristics, special attention should also be paid to safety issues to avoid damage to personnel and equipment.