What causes the efficiency of submersible pumps to decrease?

Submersible pumps are an important component of sewage systems and bear great safety responsibilities. The operational efficiency of submersible pumps directly determines the working efficiency of sewage systems. Sometimes, we may find that the operating efficiency of submersible pumps has decreased. What is the reason for this?
1, The surface of the submersible pump impeller is caused by cavitation. When the submersible pump is running, negative pressure will be generated on the back surface of the impeller blades, and long-term exposure to negative pressure can easily lead to cavitation problems.
2, Caused by volume loss and mechanical loss of submersible pumps. During long-term operation, submersible pumps experience leakage and increased resistance due to mechanical wear, which reduces volumetric efficiency and mechanical efficiency.
3, Caused by an increase in the friction coefficient inside the pump. In the long-term operation of submersible pumps, the water flow continuously erodes the inner wall and impeller over the water surface, resulting in surface roughness, increased friction coefficient, and reduced hydraulic efficiency.
4, Caused by processing technology during the production process of submersible pumps. Due to manufacturing defects, cavitation, abrasion, corrosion, and chemical erosion caused by the manufacturing process of the diaphragm pump, voids or cracks are formed in the flow channel of the submersible pump. When water flows, the submersible pump vortex is generated, resulting in energy loss.
5, The accumulation of scale or corrosion inside the submersible pump casing. The submersible pump is affected by the added drugs or water quality, causing severe scaling or corrosion inside the pump casing, forming scale nodules on the inner wall of the pump, reducing the volume of the pump body, reducing pumping capacity, and roughening the flow channel, resulting in increased head loss.