*    During working process, the engaged power screws and the driven screws form the sealed chamber with the pump casing. With rotation of the screws, the fluid makes axial movements following the seal chamber, and is transmitted stably and continuously to the delivery side of the pump.
 
 *   While pumping, the volume of the seal chamber remains constant during the working process, so no pulsation occurs.
 
 *    Independent-lubricated timing gears are adopted to transfer torque from power screw to driven screw to ensure no metallic contact or dynamic transfer is produced between the working components. The reliability of the components guarantees the pump harm free even when dry running happens in the short time.
 
  *   The specially designed suction side ensures the axial velocity of the fluid relatively low, thus ensure the pump is with very-low NPSHr value and strong capability of suction height. Besides, the unique structures of the suction and discharge side enable the pump store enough fluid while it stops, so it possesses relatively high self-priming abilities.