"Blower Fan" Its greatest feature is used when the pressure to be adjusted within the allowable fluctuation range of little traffic, select a wide range of pressure, a mandatory gas transmission characteristics. When the transmission medium is not oil. Simple structure, easy maintenance, long service life, machine vibration. Vacuum pump. Since the periodic suction and discharge and transient isochoric compression caused by pulsating flow velocity and pressure, and thus will have a greater aerodynamic noise. In addition, between the rotor and the gap between the rotor and the cylinder will cause gas leakage, so that the efficiency is reduced. Roots blower displacement is 0.15 to 150 m3 / min, the speed of 150 to 3000 r / min. Single-stage pressure ratio is typically less than 1.7 up to 2.1, you can use multi-level series.