liquid is delivered in axial direction continuously without agitation, and pulsation, so screw pump has constant capacity and pressure, smooth running, small vibration and low noise. screw pump has a very high suction capability. it needn't bottom valve and other equipments. the drive screw is driven by motor and the idler screw is driven by the pressured liquid, between the drive screw and idler screws, screw set and insert an oil film is formed, so the mechanical friction is minimized and a longer life is ensured. screw pump has single suction, double suction and horizontal installation, vertical installation pump. in order to ensure the safe working of pump, motor, piping system, screw pump is equipped with safety valves.