9 Questions For Maintenance Of Centrifugal Pump

9 questions for maintenance of centrifugal pump

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1. 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. 

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2. Why should the outlet valve be closed when the centrifugal pump is started?

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.

3. 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.

4. What are the consequences of cavitation of centrifugal pump?

Answer:

(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.

5. 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。

6. 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.  

7. What harm will be caused by the 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.

8. What measures have been 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.

9. What is the main reason why the centrifugal pump can not 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.