Causes and hazards of centrifugal pump idling

The idling of a centrifugal pump is very harmful to the pump. It will not only cause the temperature inside the pump to rise abnormally, but also may cause cavitation. In severe cases, it will damage the impeller, mechanical seal and pump housing. Today we will explore the causes and hazards of idling of centrifugal pumps.

• Reasons for idling:

The water pump has insufficient inlet medium or insufficient water inlet pressure, or the water pump inlet pipe is blocked, or the air in the water pump cavity has not been completely exhausted.

• Hazards of idling

The impact on the water pump is mainly in the following aspects:

(1) Since there is a large amount of gas in the idling pump, it is easy to cause cavitation and damage the pump body and flow channel components;

(2) The mechanical seal or packing seal has no liquid lubrication, and dry grinding is very likely to cause wear;

(3) The balance plate of the multi-stage centrifugal pump is not lubricated, and the balance plate will soon burn and damage.
(4) If there is no liquid when the water pump is idling, the rotor components and the pump body will heat up and cannot be cooled. Thermal expansion and contraction will easily cause some gaps (such as sealing rings) to lock.

• Early warning and maintenance

(1) The gap position of the irrigation centrifugal pump should be enlarged under permitted conditions to prevent the pump from stopping;
(2) The shaft of the centrifugal pump is treated with special processes, such as tempering and heat treatment, to increase the hardness, and low-flexibility materials are used to prevent the shaft from swinging too much so that the shaft will not stop running when idling;
(3) Mechanical seals and packing chambers that do not require liquid medium lubrication are used;
(4) Sealed self-lubricating bearings are selected, and no oil injection is required;
(5) Compared with other centrifugal pumps, the horizontal self-priming centrifugal pump has a larger volume space and a place to store water. Before the self-priming centrifugal pump works normally, the cavity should be filled with liquid. There is a period of self-priming time before working. During this period, air is continuously discharged to the outside of the pump, which is part of the idling;
(6) An idling induction system is set up. The pump is monitored in real-time through modern equipment. When the centrifugal pump is idling, an alarm is immediately triggered and the pump is automatically shut down to ensure the safety of the unit.