Common Faults and Troubleshooting Methods for Multistage Pumps

Multistage centrifugal pump fails to draw water, with pressure and vacuum gauge needles vibrating violently:
Possible causes include insufficient priming water, air leakage at pipe-instrument connections, or excessive suction lift. Solutions involve checking whether the pump’s foot valve is leaking and ensuring adequate priming, tightening leaky connections, and reducing the suction height.

Horizontal multistage centrifugal pump fails to draw water, with vacuum gauge showing high vacuum:
This may occur due to a closed or clogged foot valve, excessive resistance in the suction pipeline, or a blocked filter. Solutions include inspecting the foot valve, replacing the suction pipe, and cleaning the filter.

Pressure gauge shows pressure, but no water discharge:
Possible causes are excessive resistance in the discharge pipe, incorrect rotation direction, closed discharge valve, or clogged impeller. Corresponding solutions include inspecting or shortening the pipe, checking the motor and correcting rotation direction, opening the discharge valve, and clearing debris from the impeller.

Multistage centrifugal pump fails to achieve designed flow rate:
This may result from air intake, insufficient submersion depth due to lowered water level, foreign objects clogging the impeller, or severe wear in the rotor. Solutions involve checking and sealing air leaks, extending the suction pipe and increasing submersion depth, disassembling to remove blockages, and replacing sealing rings.

Excessive power consumption in horizontal multistage pumps:
Possible causes include overly tight packing, excessive flow rate, friction between rotating parts and the casing, worn bearings, or a bent pump shaft. Solutions include loosening the packing appropriately, reducing the gate valve opening, adjusting the alignment of rotating parts and casing, replacing bearings, and straightening or replacing the pump shaft.

Increased vibration in horizontal multistage pumps:
This may be caused by partial impeller blockage, impeller damage, excessively low flow rate, misalignment between the pump shaft and motor, damaged bearings, or cavitation due to air intake. Solutions involve disassembling to remove blockages, replacing the impeller, slightly opening the discharge valve, realigning the shaft, adjusting the suction position, and improving the suction pipe.

Overheating of the drive shaft or motor bearings in mining multistage pumps:
This may result from insufficient lubrication or bearing failure. Solutions include adding lubricant or replacing the bearings.

Note: Before performing any of the above operations, ensure the multistage centrifugal pump is powered off to guarantee safety. If you are unsure about the procedures, it is recommended to contact professional technicians for inspection and repair.