ABSTRACT
Vacuum pumps are subdivided by purpose into ultrahigh-vacuum, high-vacuum, mediumvacuum, and low-vacuum, and by the principle of action, into mechanical and physicochemical. Working pressure ranges of mechanical types of vacuum pumps are given at Fig. 4.1. The main parameters of any vacuum pump are the pumping speed, the limiting pressure, the lowest working pressure, the highest working pressure, the highest pressure of start, and the highest output pressure.
