When atmosphere has been removed from an enclosure, the area within the enclosure is called a vacuum. A complete vacuum is a space devoid of pressure. In practice, it is impossible to create a complete vacuum.
No machinery can completely remove atmospheric pressure from a space, but different vacuums can create varying levels of low atmospheric pressure depending on their construction. Liquid ring vacuum pumps are not the most powerful vacuum pump systems, but they are effective and reliable.
They are used in many industrial processes including the vacuum forming of products like egg cartons and other forms of packaging. They can also be used in more complex industrial applications like soil remediation (the collection of contaminated groundwater) and petroleum refining.
Vapor recovery processes, which involve the reuptake of vapors created or released by an industrial process, are often accomplished with the use of a liquid ring vacuum pump.
Liquid ring vacuum pumps are made up of a circular enclosure, a rotating vane with paddles, a set volume of liquid and openings for intake and outlet of gas from the vacuum enclosure.
The liquid in a liquid ring vacuum is often water, but it can also be oil or another liquid. Depending on the properties of the gas being evacuated, water or oil may not be appropriate because of reactivity concerns. Regardless of whatever liquid is used, the process by which liquid vacuum pumps create a vacuum is always the same.
The spinning of the rotating vane causes the liquid to form a ring around the outside of the circular enclosure. This creates an air-tight seal and individual compression chambers between each of the vane’s paddles, all of which are partially submerged in the liquid at all times.
As the vane spins, it draws air through its inlet, compresses it and forces it through the outlet. The expelled atmosphere cannot rush back in through the pump because of the liquid seal.