What are the main types of Vacuum Pumps?

A vacuum pump is a type of device used to reduce the pressure of gases in a sealed chamber. In many industries, the main need is the level of pressure required to enable the production process. These pumps are classified into different types and are used in different processes according to different requirements for vacuum and displacement.

The function of the vacuum pump is that it pumps the gas out of the closed system to gradually reduce the gas molecules concentration  in the confined space so that vacuum can be created. 

Thus, depending on their operation and principle of pumping there are four kinds of vacuum pumps (you can visit Agilent Vacuum Pumps website to discover all the different technologies).

1.   Positive displacement pumps:

These types of vacuum pumps operate with a mechanism that continuously expands the cavity to allow air to flow from the outer chamber. Then the cavity is opened as well as the exhaust gas into the atmosphere. These pumps are useful for creating medium vacuum levels. A scroll pump from Agilent functions in this same manner.

2.   Momentum Transfer pumps:

These types of pumps are called molecular pumps and they move gaseous particles out of the chamber piping them out to a second pumping stage and then to the atmosphere.  These pumps are mainly used to achieve high vacuum and they work together with other  different pumps leveraging on other pumps based on different principles of operation.

3.   Regenerative pump:

Typically, they  consist of multiple sets of teeth perpendicular to the rotor of the air particles circulating in fixed drum grooves such as a multistage centrifugal pump. When the pump is combined with a Holweck pump, it reaches 1×10−5 mbar discharged directly at atmospheric force. It is sometimes called a sub-channel pump. These pumps are used to lock loads in the semiconductor process manufacturing industries.

4.   Entrapment pump:

This type of pump can be a cryogenic pump and uses cold temperatures to compress gases  to a solid state. Chemical pumps react with gases to produce hard deposits, conversely, ion pumps use strong electric and magnetic  fields to ionize and trap gas atoms in a hard substrate.

In addition to pump principles, vacuum pumps can be classified by type of lubrication and sealing system. Vacuum pumps can be wet or dry lubricated. The choice between the two mainly affects other performance factors such as wear resistance, fluid contamination, etc.

1.   Wet vacuum pump:

Unlike dry vacuum pumps, wet vacuum pumps are generally less expensive. The main lubricating fluid used is oil. Different oils are used depending on the application. Oil  supplied to the pump  and needed to generate the pumping effect,  performs additional functions such as heat removal and contaminant filtration. The disadvantage of using a wet system is that the oil comes into contact with the pumped gas. An oil separator is used downstream to separate the oil from the gas.

2.   Dry vacuum pumps:

These pumps do not have oil or any hydrocarbon participating in the pumping.  The main advantage of the dry system is that the pump is free of contaminants, no possible pollution to the vacuum system can originate from these pumps.