In the operation of centrifugal pump, idling of pump is not allowed. The majority of users "talk about the idling" of centrifugal pump. The reason is that they do not understand the causes of idling and do not know how to solve it well. In fact, centrifugal pump idling in a very short time will not cause damage (within 1 minute).
The reasons for the idling of the centrifugal pump are: the inlet medium of the pump is insufficient or the inlet pressure is insufficient, or the inlet pipe of the pump is blocked, or the air in the pump cavity is not exhausted.
When the centrifugal pump is idling, the impeller has no or little contact with the medium, so it can't work effectively, and the liquid can't be transported out normally, which are all idle work. Because there is no effective work, the load on the motor is very small, and the current generated is very small, so the impact on the motor will not be much, and the impact of centrifugal pump idling on the pump is indeed fatal. The idling water pump is easy to cavitate, causing damage to the pump body and flow passage parts; the idling of the mechanical seal or packing seal of the idling water pump will not get liquid lubrication, resulting in dry grinding, thus causing rapid damage; the idling water pump rotor parts and pumps will experience heat, without liquid cooling, and those narrow gap positions (such as sealing rings) are very tolerant due to the effect of heat expansion and cold contraction Easy to bite; idle multi-stage centrifugal pump balance plate without whose lubrication, balance plate will soon be burned, damaged.
It is suggested to improve the design of centrifugal pump to a higher level in the early warning and maintenance of centrifugal pump idling:
1、 The clearance position of the centrifugal pump shall be treated to expand under the allowable conditions to prevent it from seizing;
2、 The shaft of centrifugal pump is treated by special technology, such as tempering, heat treatment, etc. to improve the hardness, and low flexible materials are used to prevent large swing and seizure during idling;
3、 Use the mechanical seal and packing cavity which do not need to be lubricated by liquid medium;
4、 Select sealed self-lubricating bearings of centrifugal pump without oil filling.
Compared with other centrifugal pumps, the volume space of horizontal centrifugal pump increases, and there is a place where water can be stored. Before the self-priming centrifugal pump works normally, the cavity shall be filled with liquid, and there is a period of self-priming time before operation, during which air is continuously discharged to the centrifugal pump body, which belongs to partial idling.
1.During installation, the weight of the pipeline shall not be added to the water pump, and there shall be respective supports to avoid deformation affecting the operation performance and service life.
2.The pump and motor are integral structure, so it is convenient to install because they do not need to be aligned.
3.The foundation bolts must be tightened during installation to avoid the influence of vibration on the performance of the pump during starting.
4.Before installing the water centrifugal pump, carefully check whether there are hard objects (such as stones, iron particles, etc.) in the pump flow path that affect the operation of the water pump, so as to avoid damaging the impeller and the pump body during the operation of the water pump.
5.In order to facilitate maintenance and use safety, a regulating valve is installed on the inlet and outlet pipelines of the pump and a pressure gauge is installed near the pump outlet to ensure the operation within the rated head and flow range, ensure the normal operation of the centrifugal pump and increase the service life of the centrifugal pump.
6.When the pump is used in suction head, it should be equipped with bottom valve, and the inlet pipeline should not have too many bends, and there should be no water and air leakage.
7.Discharge pipeline such as check valve shall be installed outside the gate valve.