Regardless of the technology, the essential functioning principle of an industrial vacuum pump stays the same. Air molecules (and other gasses) are removed from the vacuum chamber using vacuum pumps (or the outlet side if a higher vacuum pump is connected in series). The removal of extra molecules gets progressively difficult when the pressure in the chamber is lowered.
As a result, an industrial vacuum system must be capable of operating across a significant percentage of a very wide pressure range, often ranging from 1 to 10-6 Torr / 1.3 to 13.3 mBar of pressure. This is extended to 10-9 Torr or below in research and scientific applications. In a normal vacuum system, multiple types of pumps are employed to do this, each covering a section of the pressure range and working in series at times.
