الوصف

A Roots vacuum pump is a rotary positive-displacement type of pump where two symmetrically-shaped impellers rotate inside the pump casing past each other in close proximity. The two rotors have a cross section resembling approximately the shape of a figure 8 and are synchronized by a toothed gear. The clearance between the rotors and the casing wall as well as between the rotors themselves amounts only to a few tenths of a millimeter. For this reason Roots pumps may be operated at high speeds without mechanical wear. Roots pumps are used in pump combinations together with backing pumps (rotary vane- and rotary plunger pumps) and extend their operating range well into the medium vacuum range.