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Centrifugal Pump Common Problems And Solutions

Published on 2019/10/18

There are many kinds of centrifugal pump problems, such as inherent faults of equipment, installation problems, operation faults, and type selection errors. For example, the pump can’t start normally, no water out or the flow is insufficient, pump vibration and noise, bearing heat, etc. When judging the faults of the centrifugal pump, we should combine the basic index of equipment condition and rich maintenance experience to diagnose. The following introduces some centrifugal pump common faults.

5 Centrifugal Pump Common Problems and Solution

Horizontal Centrifugal Pumps for Water Supply Company

Motor can’t normal start

If the motor is used as the prime mover, first use the hands to switch the cooling fan of the motor to see whether the rotation is flexible. If flexible, it may be the start capacitor failure or capacity reduction which needs to replace. if die, it explains the rotor is stuck. It should cleaning rust add lubricating grease, or remove the stuck rotor foreign body.

Reverse rotation of pump

This is a common problem when first used which should immediately stop. If the motor for power, it should replace three-phase power supply any two-phase. The operation can change the direction of rotation of the pump. If the diesel engine for power which should consider the way the belt connection.

After pump rotation, no water out

If the rotation is normal but the water out, the possible reasons are:
1) the inlet is blocked by sundries, the filter should be installed after cleaning.
2) the suction pipe or instrument is leaking, which may be from welding seam, the pipe has a sand hole or crack, the joint gasket seal is not good, etc.
3) the suction height is too high, reduce.
4) the Impeller cavitation.
5) the amount of water injected into the pump is not enough.
6) there is air in the pump, the emptying method is to close the pump outlet regulating valve, open the loop valve.
7) the outlet resistance is too large, should check the length of the water pipe or clean the outlet pipe.
8) The pump speed is not enough, should increase the pump speed.

Abnormal sound or excessive vibration

When the pump operating normal, the whole pump equipment should be stable, and the sound should be normal. If there is noise or abnormal vibration of the unit, it is often the precursor of pump failure. We should immediately check to eliminate hidden dangers. The reason for the pump unit vibration is very complicated. From the cause of vibration, it is mainly mechanical, hydraulic, electrical and so on. From the mechanism of vibration, it is mainly added vibration force is too large, rigidity is insufficient, and resonance.

Bearing overheating

When running, if the bearing is hot, the reasons should be checked and dealt with from the following aspects:
1) insufficient lubricating oil or poor oil circulation.
2) poor quality lubricating oil and impurities make the bearing rust, wear and rotation are not flexible.
3) serious bearing wear.
4) the pump and motor are not the same center.
5) the bearing inner ring and the pump shaft neck fit too loosely or too tightly.
6) the belt is too tight when driving with the belt.
7) the axial thrust is too large, the balance hole on each impeller should be dredged.

What Centrifuge Pump

Centrifugal pump is widely used in electric power, metallurgy, coal, building materials and other industries to conveying slurry containing solid particles. Such as power plant hydraulic ash removal, metallurgical ore dressing plant slurry transport, coal washing plant slurry, and heavy medium transport.

Centrifugal pump structure

The centrifugal pump structure can be divided into horizontal and vertical centrifugal pumps according to the position of the shaft. According to the type of exit chamber and suction mode, it can be divided into the snail pump and guide vane pump. Centrifugal pump composition is relatively simple, which mainly composed of four parts: prime mover, impeller, pump shell, and shaft seal device.

structure of centrifugal pumps

Working principle of centrifugal pump

Take the common water pump as an example, before starting, the pump shell should be filled with liquid first. After starting, the impeller rotates at high speed driven by an electric motor. When the impeller rotates, the water pressure at the impeller inlet is lower than the atmospheric pressure. And along the impeller radius of the direction of the water pressure rising, far higher than atmospheric pressure. So in the intake pipe to form a certain suction. Under the atmospheric pressure of the outside world, the water in the lower part pushes the water inlet valve into the pump shell along the water inlet pipe, and thrown into and out of the water pipe by the impeller. Then the water at the bottom can be pumped continuously to the top.