1. Due to the washing of the water flow, the inner wall and the impeller surface of the pump flow duct became rough and uneven. The resistance coefficient of the flow channel inner rivers in the pump pump increased. In addition, the flow rate of the water in the pump was very large, and the water head loss increased. Hydropower is reduced.

2. Due to adding drugs or water quality in front of the pump, severe dirt or corrosion in the pump shell. The severe accumulation in the pump shell can increase the wall thickness of the pump shell to increase by about 2ram, and the inner wall of the pump can form staintoma, which reduces the volume of the pump body, reduces the amount of water pumping, and rough the flow channel, and the loss of water head. The accumulation efficiency and hydraulic efficiency are reduced.

3. Casting defects, etching, abrasion, corrosion, and chemical perforation caused by the pump processing process causes empty or cracks in the pump flow duct, and vortex occur during water flow to cause energy loss. Hydropower is reduced.

4. Stele erosion on the surface of the impeller. Due to negative pressure when the leaves are running on the back of the water, when the pressure is PK <PVA, after the surface of the steam acupoint and honeycomb is generated, the pump leaves are eroded under electrochemical corrosion.

5. Losses and mechanical losses. Due to the long period of use of the pump, the leakage and resistance of mechanical wear were increased, which reduced the volume efficiency and mechanical efficiency.