There are many different types of vacuum pumps such as liquid ring vacuum pump, rotary vane vacuum pump, roots vacuum pump, rotary piston vacuum pump, molecular vacuum pump, but the main function of a vacuum pump is to pull air or gases out of a container. The air or gas is sucked or pumped out, leaving the container void of any or most air or gas molecules. Forms of vacuum pumps are used in household and commercial vacuum cleaners, for vacuum sealing food, or vacuum packing other objects you wish to save from the elements. The type of vacuum pump discussed in this article are absolute vacuums, used to suck all the air and gas molecules from a container; such vacuums are used in space training applications.
Also called kinetic pumps, these types of pumps create momentum, through a piston or propeller-like device pushing the gas around the inner parts of the vacuum pump, continuously flowing from the inlet to the outlet of the pump. The piston or other moving part of the pump accelerates the gas and air molecules, creating an area of low pressure. The gas and air molecules begin moving away from the low-pressure region and escape through the outlet valve of the pump. When the desired amount has been removed from the vacuumed chamber, a closure valve is put into place to prevent the molecules from being pulled back into the container from the pump.
To perform more effectively, trapping pumps, also known as capture pumps, are usually placed inside the container that is being vacuumed. These types of pumps work using chemical reactions; for example, some trapping pumps operate by removing the condensation or thin film created by the molecules in the air when they chemically react to the internal surfaces of the pump.
The basic information you need to know to understand how vacuums work is how the low pressure regions power the vacuum system. Molecules in the air do not like the areas of low pressure and rush to immediately escape to higher-pressure areas. Tornadoes are excellent examples of natural vacuums, creating such a chaos as air and gas molecules rapidly search for areas of higher pressure.