Rotor pump classification and definition is as follows: A. Screw pump: Screw pump is a single screw pump, its main working parts are eccentric screw spiral (referred to as the rotor) and the inner surface of the double helical screw bush (called stator). B. Liquid ring pump: C. Gear Pumps: Rotary pumps that deliver or pressurize liquids by changing and moving the working volume created by the pump cylinder and meshing gear. D. Slide pump: E. Roots pump: a vacuum equipment, is a kind of vacuum pump without internal compression, the compression ratio is usually very low, so high, the vacuum pump requires a foreline pump. F. Roller pump: G. Cam pump; Peristaltic Pump: Pump fluid by alternately squeezing and releasing the pump's flexible delivery hose.