Basic Skills For Maintenance Of The Centrifugal Pump

Do you know the skills for maintenance of the centrifugal pump?Today let us talk together!


What are the vulnerable parts of centrifugal pump?

Answer: bearing, shaft sleeve, impeller mouth ring, shell mouth ring, mechanical seal dynamic and static ring, seal ring, opposite wheel rubber ring, cancellation coupling spring gasket, etc.


Why to close the outlet valve when the centrifugal pump starts?

Answer: because when the flow of centrifugal pump is equal to zero, the power is minimum. In this way, the starting current of the motor can be reduced and the motor can be protected.


How is the rated flow, head and power of centrifugal pump regulated?

Answer: when the centrifugal pump efficiency is the highest, the flow, head and power are determined as the rated flow, head and power of the centrifugal pump.


What are the consequences of centrifugal pump cavitation?

A: (1) generate noise and vibration;

(2) With the decrease of flow, head and efficiency, it is impossible to operate;

(3) There are pockmarks and honeycombs in the impeller shell and blade, which may even cause the shell to penetrate;

(4) Damage to the pump shaft.

centrifugal slurry pump


Does the flow change of centrifugal pump produce radial force in normal operation?

Answer: can produce radial force. Because the change of flow rate makes the pressure distribution around the impeller uneven, the radial force acting on the impeller is formed


What kind of harm will be caused by the radial force of centrifugal pump?

Answer: because the radial force of centrifugal pump is vertical acting on the pump shaft, so the pump shaft will produce a larger deflection (official account: Pump housekeeper), and the rotating shaft will be subjected to alternating force. Therefore, the force of the pump will cause fatigue damage to the pump shaft.


What harm will be caused by axial force of centrifugal pump?

Answer: the existence of axial force of centrifugal pump will cause wear of ring, balance plate and impeller; damage of mechanical seal, bearing and motor.


What measures are taken to eliminate the axial force in the design of centrifugal pump?

(1) Balance hole, balance plate, balance tube and balance drum are used;

(2) Impeller double suction;

(3) Use thrust bearing;

(4) Use symmetrical arrangement of impeller, etc.

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What is the main reason why the centrifugal pump can't supply water?

(1) There is gas in the pump inlet and inlet pipe;

(2) The increase of medium viscosity is inconsistent with the design;

(3) Leakage of inlet pipeline or mechanical seal;

(4) The inlet pipeline is blocked;

(5) At the end of the pump revolution, the rated revolution is reached;

(6) Pump reverse;

(7) The gap between the ring and the mouth is too large.


What are the main causes of centrifugal pump vibration?

(1) The coupling is not concentric;

(2) The bending degree of shaft exceeds the standard;

(3) Excessive or damaged bearing clearance;

(4) Rotor unbalance;

(5) Friction between rotor and stator;

(6) The medium carries gas and has cavitation;

(7) Pump out;

(8) There are foreign matters in the impeller passage;

(9) The unreasonable installation of process pipeline makes the pump subject to external force.

(10) Low load operation for a long time;

(11) The influence of the vibration of the accessory pipeline;

(12) Foundation bolts are loose.


What are the causes of Bearing Overheating of centrifugal pump?

(1) Poor quality of rolling bearing or wear during operation;

(2) The clearance of sliding bearing is too small;

(3) Poor cooling of bearing box;

(4) Insufficient or excessive amount of lubricating oil and grease or impurities.


There are several reasons for the centrifugal pump motor current is too large?

(1) The medium weight or viscosity is too large, which is inconsistent with the design;

(2) Serious friction between rotor and shell;

(3) The coupling is not concentric or the bearing is worn.


Which types of centrifugal pump rotors need only static balance?

(1) Single stage pump;

(2) Small diameter multistage pump rotor;

(3) Lower speed rotor.


Which type of centrifugal pump rotor must be installed to find dynamic balance?

(1) More impellers;

(2) Larger diameter;

(3) High speed rotor.


What are the methods of coupling alignment?

(1) Single table alignment;

(2) Double table alignment;

(3) Three table alignment.


What are the reasons for the unstable or large fluctuation of the pointer of the pressure gauge at the outlet of the centrifugal pump?

(1) The indicator of pressure gauge damage is not working;

(2) Pump evacuation or flow fluctuation;

(3) Impurities or blockage in the pipeline;

(4) Pump vibration;

(5) Gas in pipeline or pump casing;

(6) Cavitation.


What is the effect of centrifugal pump on mechanical seal?

(1) It will cause a lot of leakage of mechanical seal;

(2) Destroy the sealing surface of mechanical seal and even cause damage.


What is the maximum allowable bending value of centrifugal pump shaft?

At the Journal: no more than 0.02mm;

Middle axis:

(1) 1500 rpm is not more than 0.08mm;

(2) 3000 rpm is not more than 0.06mm.

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