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Mastering the Art of Vacuum Pump Selection: Your Ultimate Guide to Different Types
A vacuum pump is a device that removes air from a sealed space so that a low-pressure or vacuum is created. It works by creating a negative pressure gradient in the enclosed space. This allows the air to be sucked out of the sealed volume. The process of creating a vacuum is called evacuation. The process of creating a high vacuum or partial vacuum is called degassing. In most applications, vacuum pumps are used to reduce the pressure in a tank of liquid or to suck particles and gas molecules out of a sample.
The purpose of vacuums is to suck in gas molecules from outside of the container or to let them out when the pressure inside is greater than the pressure outside.
Vacuum pumps are typically used in manufacturing, packaging, and scientific applications. Some common examples include A general-purpose air pump that creates positive pressure to inflate balloons or tires, a diaphragm pump that creates a partial vacuum for industrial uses, and the steam engine which uses high-pressure steam to create a vacuum.
Types of Vacuum Pumps
There are many types of vacuum pumps in the market. One of the most popular and widely used in industry and science is the diaphragm pump. It is also called a positive displacement pump.
- Positive Displacement Pumps
- Rotary Vane Pumps
- Diaphragm Pumps
- Piston Pumps
- Momentum Transfer Pumps
- Diffusion Pumps a. Working Principle
- Turbomolecular Pumps
- Entrapment Pumps
- Cryogenic Pumps
- Ion Pumps
- Regenerative pump
Positive displacement pump
A positive displacement pump is the most common type of pump used in industrial applications. This kind of pump is usually made up of a sealed chamber that contains fluid. The vacuum is generated by expanding and contracting the sealed chamber, thereby drawing the fluid in and ejecting it out. Positive displacement pumps operate by the same principle as a diaphragm pump. However, the pressure needed to make the piston move is much higher than that of the diaphragm.
Positive displacement vacuum pumps are used for industrial applications. They are also used for air conditioning and refrigeration purposes. They are more efficient than displacement pumps because they use less power. Vacuum pumps are mostly used in vacuum tubes, rocket engines, and the aerospace industry.
- Reciprocating Vacuum Pumps and
- Rotary Vacuum Pumps
Reciprocating Vacuum Pumps
- Reciprocating piston vacuum pumps
- Plunger vacuum pumps, and
- Diaphragm vacuum pumps
Rotary Vacuum Pumps
A rotary vacuum pump is a machine that creates low pressure through the rotation of the moving components against the pump housing. Rotary vacuum pumps work by creating a vacuum region around the rotor shaft. This vacuum can be achieved by the pressure differential between the inlet and outlet. If there is a pressure difference between the two sides, the inlet side will be lower in pressure than the outlet side. The rotor is connected to the shaft and moves around the shaft when it is rotating. The housing is a cylinder that has an opening on the side. The inlet and outlet are located at one end and the rotor is located at the other end. When the rotor is connected to the shaft, it rotates. The inlet and outlet open up and close in order to let the air into and out of the pump.
In comparison with reciprocating pumps, rotary vacuum pumps are designed with lower pulsating delivery, and the flow is more continuous. Rotary vacuum pumps are not suited to handle fluids containing abrasive media as it can erode the small clearances between the rotor and the housing.
The seven main types of rotary vacuum pumps are:
- Rotary Vane Vacuum Pump
- Liquid Ring Vacuum Pump
- Rotary Piston Vacuum Pump
- Screw Vacuum Pump
- Gear Vacuum Pump
- Lobe Vacuum Pump
- Scroll Vacuum Pump
Rotary Vane Vacuum Pump
Roller vane rotary vacuum pumps use a single-piece rotor that revolves against a stationary cylindrical housing. The rotor and the housing have complementary external and internal surfaces, which are not in contact with each other. The clearance between the surfaces is filled with fluid. The rotor is equipped with multiple vanes that face the housing and are open to the low-pressure side. When the pump is started, the rotor moves toward the housing. The rotation of the rotor creates a pressure difference between the high-pressure and low-pressure sides. The fluid is sucked into the pump.
Momentum Transfer Pumps
Momentum transfer pumping is used to move the particles from one place to another. It is similar to what happens when you pump water from one container to another. When you open the valve on the container, some of the water moves through the opening and into the next container. This makes the flow of the water more powerful. As the water enters the next container, it pushes the air out of the first container. That’s how the momentum transfer pumping works.
There are two main types of molecular pumps used to extract atoms form a gas. The first one is called a diffusion pump. This is a simple pump that uses a jet of oil or mercury vapor to expel the gas from the chamber. It is a low-cost and easy-to-use pump. The second type of pump is called the turbomolecular pump. This is a more expensive pump. It works on the principle of an electric motor with a high-speed fan to create a high-velocity jet of air that pushes the gas from the chamber.
These two types of pumps work in different ways. The first one, a diffusion pump, uses jets of oil or mercury vapor to expel the gas molecules from the chamber. On the other hand, the turbomolecular pump uses a high-speed fan to push out the gas molecules from the chamber. Both these pumps can be used for scientific experiments because they can create a vacuum of about 4.1 torrs (5.001 mbar). However, they are also much more expensive than a diffusion pump.
- Turbomolecular Vacuum Pump
- Diffusion Vacuum Pump
Regenerative pump
Regenerative pumps use the vortex behavior of the fluid, which is caused by the difference in speed of the fluid. They are also called vortex pumps. The idea is to circulate air molecules in a chamber while applying an external force. The external force is usually provided by a turbine.
The rotor in a regenerative pump uses several rows of teeth. The teeth are perpendicular to each other and are arranged in a spiral shape. This creates a vortex motion as the fluid passes between the teeth. This pump has lower power consumption than the conventional centrifugal pump. The power required to run the pump is low.
It is important to know that regenerative pumps are normally used to pump air. However, these pumps can also be used to pump other fluids such as water, oil, etc. These pumps are commonly known as air pumps.
Regenerative pumps are pumps that use air as a liquid. Regenerative pumps have air passageways that allow air to circulate through the pump. This type of pump is usually used to get air into a building. It has many different parts and is made in several sizes.
Entrapment Vacuum Pumps
Entrapment vacuum pumps use physical and chemical phenomena to capture gas molecules. An entrapment pump is an amazing tool used by scientists to remove gases from the air, which is an important job. This device works by using the principle of the cryopump to remove gases from the air. A cryopump uses cold temperatures to condense gases to a solid or adsorbed state, so they will stay in a liquid form. Once the gas has been condensed into a solid, it can be removed and used in scientific experiments.
The first thing you need to know about an Entrapment vacuum pump is that they don’t rely on any moving parts. This means that you do not need to worry about the reliability of the vacuum pump when it’s working. The second thing you should know is that they cannot operate continuously since they need to be regenerated once the surface or material capturing the gases is full. You should also know that they cannot remove lighter gases such as hydrogen, helium, and neon.
- Cryogenic Vacuum Pump
- Sorption Vacuum Pump
- Sputter Ion Vacuum Pump
- Titanium Sublimation Vacuum Pump
6 Factors to Consider When Choosing a Vacuum Pump
When selecting a vacuum pump for your specific application, several factors should be taken into account:
- Operating Parameters – Consider the required vacuum level, gas composition, and permissible pressure fluctuations.
- Required Vacuum Level – Determine the desired vacuum range, from rough vacuum to ultra-high vacuum, based on your application’s requirements.
- Pumping Speed and Capacity – Evaluate the required pumping speed to achieve and maintain the desired vacuum level within a specific time frame.
- Chemical Compatibility – Ensure the pump materials and design are compatible with the gases or vapors involved in your process.
- Maintenance and Serviceability – Assess the maintenance requirements, such as oil changes, part replacements, and availability of service support.
- Cost Considerations – Consider the initial investment cost, operational expenses, and the overall cost-effectiveness of the chosen pump.
Selecting the Right Vacuum Pump for Your Application
Different applications require specific vacuum pump types. Here are some common application areas and the recommended vacuum pump types for each:
Laboratory and Research Applications – Rotary vane pumps, diaphragm pumps, and turbomolecular pumps are often suitable for laboratory-scale processes and research experiments.
Industrial Manufacturing and Processing – Piston pumps, diffusion pumps, and cryogenic pumps are commonly used in industrial settings for high-capacity and continuous operation.
Medical and Pharmaceutical Applications – Diaphragm pumps, rotary vane pumps, and cryogenic pumps find applications in medical devices, pharmaceutical production, and vacuum freeze-drying.
HVAC and Refrigeration Systems – Rotary vane pumps and reciprocating pumps are commonly used in HVAC systems, refrigeration, and air conditioning units.
Other Specialized Industries – Depending on the specific requirements, specialized vacuum pumps types such as ion pumps, turbomolecular pumps, or customized solutions may be required.
Conclusion
A vacuum pump works by removing air from a chamber and then creating a partial vacuum inside it. This causes the pressure on the side of the chamber opposite the suction opening to increase, which creates an inward force to move the diaphragm. In other words, the pressure gradient at the chamber walls causes a pressure gradient across the diaphragm which will pull it inwards. When the vacuum is strong enough, the diaphragm is pulled down and the piston will rise. The vacuum can be generated using either a compressor or a turbine.
