By the principle of twin-screw pump know, for the external bearing twin-screw pump, through the bearing positioning, the two screws in the bushing do not touch each other, to maintain a constant gap between the flanks (the gap value by the conditions and the pump itself Specifications), the screw cylindrical and bushing inner surface remains constant gap unchanged. Two screw drive by the synchronous gear to complete. There is a separate lubrication in the gearbox, separated from the pump working chamber. The advantages of this structure greatly broaden the use of dual-screw pump, that is: In addition to conveying a good lubrication medium, but also transport a large number of non-lubricative media, a variety of viscosity (the highest viscosity up to 3 * 106mm / s) Of the medium and corrosive (acid, alkali and other properties), abrasive liquid. Due to their constant clearance and profile features, twin-screw pumps are non-hermetic positive displacement pumps and therefore deliver a mixture of gas and liquid, that is, a mixture of gas and liquid, in addition to the pure liquid, which is also twin screw One of the advantages of pumps is very unique. Twin screw pump due to the unique structure of the design, can be self-priming without the need for special self-priming device, but also due to the axial transport axial flow velocity is small and have a strong suction capacity that is small NPSHr value. Twin screw pump can also dry rotation. Because the moving parts do not touch each other during work, short-term dry rotation will not damage the pump components. This feature greatly facilitates the automatic control flow, but the dry running time is limited by many factors and is generally short . In addition the twin-screw pump in the transport process without shear, no emulsification, it will not undermine the molecular chain structure and working conditions in the process of the formation of a specific fluid properties, and because the transmission relies on synchronous gear, pump low noise, low vibration Work steadily.