Types of Vacuum Pumps and Their Uses
Last Updated on October 11, 2024
Vacuum pumps are mechanical devices that create a vacuum by removing gas molecules from a chamber. This is done by either mechanically compressing or accelerating the gas molecules. To understand the various types of vacuum pumps, you must first know the primary difference between wet and dry vacuum pumps.
Wet vacuum pumps use water or oil in the pumping chamber to lubricate the moving parts and to create a vacuum. Dry vacuum pumps do not have fluid in the chamber, but they have oil for the gears and bearings to lubricate them.
Now, let’s look at different types of vacuum pumps based on their mechanism.
Types of Vacuum Pumps
Vacuum pumps are broadly classified into positive displacement, kinetic, and entrapment vacuum pumps. Here is a list of all the vacuum pumps available in the market.
Positive Displacement Vacuum Pumps
A positive displacement vacuum pump works by trapping a fixed volume of air inside the chamber and then mechanically compressing it to push the air outside and create a vacuum. These pumps are suitable for low vacuum applications and provide a moderate suction flow. The types of positive displacement vacuum pumps are:
- Oil Sealed Rotary Vane Pumps
- Diaphragm Pumps
- Liquid Ring Pumps
- Claw Pump
- Screw Pump
1. Oil-Sealed Rotary Vane Pumps
These pumps consist of a rotor inside a cylindrical chamber. The rotor traps gas molecules using vanes or shafts to create a vacuum. Oil-sealed rotary vane vacuum pumps are suitable for high-vacuum applications and are typically used in laboratories.
2. Diaphragm Pumps
A flexible metallic or elastomer membrane is used by diaphragm vacuum pumps to create a hermetic seal inside the pumping chamber. The air is trapped by the up-and-down111 movement of the diaphragm to create a vacuum. Diaphragm pumps are used in the pharmaceutical and chemical industries.
3. Liquid Ring Pumps
As the name suggests, liquid ring vacuum pumps use liquid (generally water) to rotate and create a vacuum. The pumps are suitable for moisture-containing gases and are used in chemical industries.
4. Claw Pumps
These pumps consist of meshing claws that rotate in opposite directions to compress the gas. It is a dry type of vacuum pump that is efficient and requires less maintenance. Claw pumps are used in food processing, pharmaceutical, aerospace and other industrial operations.
5. Screw Pump
Screw pumps use two rotating screws that rotate in opposite directions to create a vacuum and discharge air. This is a dry-type positive displacement vacuum pump. These pumps are suitable for handling gases and vapours. Screw pumps are used in metallurgy, wastewater treatment and chemical processing.
Kinetic Vacuum Pumps
Kinetic vacuum pumps are also known as momentum transfer vacuum pumps. These pumps move gas in the pumping direction by accelerating it with a mechanical drive system or directed vapour steam to create a vacuum. These pumps are best suited for high or ultra-high vacuum applications and are used in manufacturing and research labs. The kinetic vacuum pump types are:
- Turbomolecular Pumps (Dry)
- Vapour Diffusion Pumps (Wet)
1. Turbomolecular Pumps
These pumps utilise angular blades or rotors at high speeds to transfer kinetic energy to gas molecules. Turbomolecular vacuum pumps are highly efficient and are used in the production of semiconductors and spectrometry.
2. Vapour Diffusion Pumps
Vapour diffusion pumps use a high-velocity heated oil stream to “drag” the gas from the intake to the outlet, transferring kinetic energy to gas molecules and lowering the input pressure. These pumps are used for high-vacuum applications such as vacuum coating and high-vacuum furnaces.
Entrapment Pumps
These pumps are also known as capture pumps. Entrapment pumps create a vacuum by trapping gas molecules in solid or absorbed states. These pumps are used for ultra-high vacuum applications. The entrapment pump types are:
- Cryopumps
- Sputter Ion Pumps
- Ion Getter Pumps
1. Cryopumps
In cryopumps, the gas molecules are cooled down at extremely low temperatures. These molecules are freezed to the walls of the chamber creating a highly effective vacuum. Cryopumps are used in particle accelerators and cryogenic systems.
2. Sputter Ion Pumps
In sputter ion pumps, gas molecules are ionised using an electric field. This ionised gas is then trapped on a solid surface to create a vacuum. Sputter ion pumps are used in ultra-high vacuum applications such as research and scientific development.
3. Ion Getter Pumps
These pumps are similar to sputter ion pumps as both ionise gas. In ion-getter pumps, the ions are attracted to a reactive metal, where they are absorbed. These pumps are used in high-vacuum environments such as high-precision instrumentation applications.
Conclusion
- Vacuum pumps are essential devices for operational efficiency and accuracy in any industrial process that requires a vacuum.
- Choosing the right one is crucial for your business. The article above covers the unique characteristics of each pump type as well as their applications.
- The applications of vacuum pumps do not just include cleaning. They are an essential part of industries such as chemical processing, pharmaceuticals, construction, aerospace, and automobiles that require high precision in different industrial processes.
FAQs
The major types of vacuum pumps are positive displacement vacuum pumps, kinetic vacuum pumps, entrapment vacuum pumps, and hybrid or specialised pumps.
A vacuum pump works by removing gas molecules from a chamber to create a vacuum or a space devoid of air. This is done by lowering the pressure of the chamber allowing the chamber to be free of gas. Vacuum pumps use either a positive displacement mechanism (compressing the gas molecule mechanically) or accelerate the gas molecule to push it out of the chamber.
The differences between a dry and a wet (oil-sealed) vacuum pump are:
(i) Dry vacuum pumps do not have any oil or liquid for sealing the chamber whereas an oil-sealed vacuum pump uses oil to seal the chamber and for lubrication of moving parts.
(ii) Dry vacuum pumps are suitable for deep vacuum applications and oil-sealed pumps are used for low or moderate vacuum applications.
