How Does a Vacuum Pump Work?
A vacuum pump, just as its name suggests, is used to create a vacuum. The vacuum it creates is not a true vacuum, though, but a partial cone. Vacuum pumps have been in existence since the 17th century. Today’s vacuum pump is a piece of sophisticated equipment and is used in numerous industrial applications.
How Does a Vacuum Pump Work?
A vacuum pump works by sucking gas out of a container or chamber by continually decreasing the number of gas molecules until a vacuum is achieved. Most vacuum pumps use rotating blades to push air out of a sealed containers, while other types feature no moving parts. The effectiveness of the work done by a vacuum pump depends on the air volume to be removed. It’s determined by the pressure difference between the chamber to be evacuated and that of the outside.
There are various versions of the vacuum pump, each with a different working mechanism it uses to suck out air. The principle of operation remains the same, though; moving air molecules away to create a region of low pressure or a partial vacuum.
Types of Vacuum Pumps
There are three types of mechanisms for removing air from a chamber that vacuum pumps use:
- Positive displacement
- Momentum transfer
- The capture or trapping method
1. Positive Displacement Vacuum Pump
This type of pump works by expanding a cavity into which air molecules from the chamber where the vacuum is to be created flows. Once the gas escapes the vacuum chamber, the cavity is sealed and the gas left to move out into the atmosphere. The cycle is repeated again and again. By continually expanding the opening for air molecules to escape the chamber through the cavity and sealing it to allow the same air to exhaust to the outside atmosphere, a vacuum is finally left in the chamber. The positive displacement vacuum pump is not very powerful. They’re only useful where low vacuums are needed
2. The Momentum transfer vacuum pump
It’s also known as the kinetic pump. The pump utilizes the force of rotating parts to force air out of the chamber air needs to be driven out from. As the moving parts continually push air molecules out, the pressure of the air left behind continues decreasing until the required pressure is reached, at which point a special valve closes. The valve is known as a High vacuum valve and works to close the opening through which air was escaping to prevent it from flowing back. As a result, a vacuum is created. The momentum displacement pump is of two types; the diffusion and the turbomolecular pumps. The diffusion vacuum pump utilizes oil jets to drive air out, while the turbomolecular vacuum pump uses fans rotating at high speeds.
3. The Entrapment Vacuum Pump
The entrapment pump removes air while inside the chamber to be evacuated, making them more efficient at removing air to create a vacuum. The pump utilizes chemical reactions instead of mechanically forcing air out.
The pump is placed in the container out of which air is to be removed and the container sealed. The pump cools the inside of the container and uses the resulting condensation to trap air molecules before absorbing them away. For increased efficiency, this type of pump is usually used together with other kinds of mechanical vacuum pumps.
Uses of Vacuum Pumps
The vacuum pump is used in many ways that include;
- In medical labs and health facilities for suction purposes
- In the car manufacturing industry
- In making of electric bulbs and tubes
- In the electronics industry when making semiconductors
- To compact trash and in sewage removal systems
- In farm machinery such as milking machines and water pumps
- In aircraft to operate some instruments, and many more other applications
Vacuum pumps are useful in many ways, especially in industrial processes. The mechanism they use keepsvon improving to make them work better and more efficiently. Today, versions of the vacuum pump exist in many different sizes and modes of operation.
The level of sophistication depends on the use. Industrial vacuum pumps are big and more complicated. Miniature vacuum pumps used for lesser tasks are small and easy to operate, with just a few moving parts. But they’re equally less efficient, which doesn’t matter because they’re mostly used to create low vacuums.