Screw pump is a positive displacement positive displacement pump, the main components are the rotor and stator, the rotor is a large gear tooth large and small screw inner diameter of the screw (rotor) stator is matched double helix and screw sleeve, so that at The space between the rotor and the stator forms a storage medium. When the rotor runs in the stator, the medium is axially moved from the suction end to the discharge end. It can be seen from the above working principle, screw pump has the following advantages: 1, a wide range of pressure and flow. Pressure of about 3.4-340 kgf / cm 2, the flow rate of up to 18600cm3 / min; 2, the type and viscosity of a wide range of liquid transport; 3, because the rotary inertia force within the pump is low, it can use high speed ; 4, good inhalation performance, self-priming capability; 5, continuous flow, small vibration, low noise; 6, compared with other rotary pumps, the gas and dirt into the less sensitive; 7, solid structure, installation Easy to maintain. The shortcomings of the screw pump is: the screw machining and assembly requirements are higher; the performance of the pump is more sensitive to changes in the viscosity of the liquid.