Common faults of centrifugal pumps and their solutions

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Causes of failure and troubleshooting methods for pipeline pumps. Pipeline pumps are widely used in both industrial production and agriculture. Pipeline centrifugal pumps possess outstanding advantages such as stable performance, small size, simple structure, easy operation, few failures, long service life, and low cost. But all machinery is prone to certain faults; below are thirteen common faults of pipeline centrifugal pumps along with their solutions: 1. Before starting the pipeline pump, insufficient water is filled in, or the vacuum pump fails to remove all the air from inside the pump. Extend the water filling time, increase the amount of water filled, and continue to use the vacuum pump to remove air. If the water level still doesn’t fill up and the air cannot be completely removed, it is necessary to check whether there are leaks in the inlet pipe, whether the bottom valve is rusted shut, and whether there are leaks at the packing gland. Then, for the problems identified, repairs or replacements are carried out accordingly. II. The installation head of the pipeline pump exceeds the rated head of the water pump. Appropriately reduce the installation height of the water pump (referring to the vertical distance between the center line of the pump shaft and the dynamic water level in the well) or shorten the length of the suction pipe; additionally, increase the diameter of the suction pipe (generally, the diameter of the suction pipe should be one size larger than that of the pump’s inlet) in order to reduce the pumping head required and increase the suction height of the pump. III. Air leakage in the inlet pipe of the pipeline pump results in poor sealing, incomplete filling with water, and failure to remove all air. Conduct an inspection using the light exposure method; if there is air leakage at the pipe wall, repair it to ensure a tight seal ； If there is air leakage at the interface, tighten it with a wrench or replace the gasket. IV. Reverse rotation of the pipeline pump impeller. The rotation direction of the water pump can be changed by altering the rotation direction of the power engine. If an electric motor is used as the power source, the wiring phase sequence of the motor should be adjusted to change its rotation direction ； If an internal combustion engine is used as the power source, adjustment should be made by employing crossed drive belts. V. The suction pipe of the pipeline pump is not submerged deep enough in water. First, measure the depth to which the suction inlet of the pipeline pump is submerged in water. If it is not deep enough, measures such as lowering the installation height of the water pump or increasing the length of the suction pipe of the centrifugal pump should be taken to ensure that the suction inlet remains at a depth of no less than 0.5 meters below the water surface. Sixth, the inlet of the pipeline pump or the flow channel of the impeller may be blocked. First, stop the pump and check to identify the exact location of the blockage; then remove the obstruction. Finally, depending on the type of blockage (such as sediment or debris), measures such as well cleaning (it is recommended to use an air compressor or other equipment) or installing trash racks can be taken to improve the quality of the water entering the system and prevent further blockages from occurring. VII. The bottom valve of the pipeline pump is not flexible enough or is rusted, resulting in it being unable to open or close properly. In case of this phenomenon, stop the vehicle first. Then lift the water pump’s faucet to the ground, remove the bottom valve for inspection, and repair or replace it as necessary. VIII. The suction height of the pipeline pump is too high. Appropriately lower the installation height of the water pump or find ways to reduce water pressure losses (such as using inlet and outlet pipes with smooth inner walls). IX. The impeller of the pipeline pump is severely damaged. Disassemble the water pump and remove the impeller for inspection; if the damage to the impeller (wear, cavitation) is not severe, it should be repaired ； If the impeller is severely damaged, it should be replaced with a new one. X. Air leakage at the packing gland of the pipeline pump results in poor sealing. First, use a tool to tighten the stuffing box gland. If the fault cannot be ruled out, the stuffing box must be disassembled to check for any defects in the water seal ring and the packing (such as twisting or deformation of the water seal ring, or hardening or deformation of the packing), and repairs or replacements should be carried out if necessary. 11. The impeller fixing nut and key of the pipeline pump are loose or have come loose. Open the pump body and check the positioning key and lock nut of the impeller. If the key is dislodged or damaged, the positioning key should be reset, or it should first be repaired or replaced before resetting. If the impeller lock nut has loosened or fallen off, the lock nuts should be replaced first, and then the impeller lock nut should be tightened using tools. 12. The rotation speed of the pipeline pump is too low. First, increase the speed of the prime mover to meet the rated speed of the centrifugal pump. For engines that are electric motors, first check whether the supply voltage is too low; if it is, try to increase it. If the voltage is normal, then replace the motor with one of higher power ； For engines that are internal combustion engines, it is necessary to first increase the throttle in order to raise the speed. If this does not allow the water pump to reach its rated speed, then a diesel engine with higher power should be used. Secondly, replace the drive wheel of the power engine or water pump (to change the gear ratio) in order to meet the rated speed of the water pump. 13. The resistance in the drainage pipe of the pipeline pump is too high. First, check the length of the drainage pipes and the number of bends; try to minimize the number of bends and the length of the pipes, and choose pipes that match the diameter of the pump. Original article: http://www.yzj.cc/contents.asp?tid=669. Please indicate the source of the article and its completeness when reproducing it