During the operation of centrifugal pump, the pump idling is not allowed. The majority of users "turn pale" at the idling of centrifugal pump. The reason for this is that they do not understand the causes of idling and do not know how to solve it well. In fact, the centrifugal pump will not cause damage (within 1 minute) when idling for a short time.

The reasons for the centrifugal pump idling are: the inlet medium of the pump is insufficient or the water inlet pressure is insufficient, or the water inlet pipe of the pump is blocked, or the air in the pump chamber is not exhausted.

When the centrifugal pump is idling, the impeller has little or no contact with the medium, so it can not work effectively, and the liquid can not be delivered normally, which is useless work. Because there is no effective work, the load on the motor is very small, and the generated current is also very small, which will have no impact on the motor. The impact of pump idling on the pump is really fatal.

The idle water pump is easy to cavitate, causing damage to the pump body and flow passage parts; Idling pump mechanical seal or packing seal will not be lubricated by liquid, resulting in dry grinding and rapid damage; The idling pump rotor parts and pumps will generate heat without liquid cooling, and the narrow gap positions (such as sealing rings) are easy to bite due to thermal expansion and contraction; The balance disc of the idling multistage centrifugal pump is not lubricated by water, and the balance disc will soon be burned and damaged.

It is recommended to improve the design of centrifugal pump by one level during the warning and maintenance of centrifugal pump idling:

1、 The clearance positions of the centrifugal pump shall be treated to expand under allowable conditions to prevent seizure;

2、 Special process treatment, quenching and tempering, heat treatment, etc. shall be carried out on the shaft of the centrifugal pump to improve the hardness, and materials with low flexibility shall be used to prevent large swing and seizure during idling;

3、 Use mechanical seal and packing chamber that do not need to be lubricated by liquid medium; 4、 Closed self-lubricating bearings without oil filling shall be selected.

Compared with other centrifugal pumps, the pump chamber of horizontal self-priming centrifugal pump has a larger volume space and a place where water can be stored. Before the self-priming centrifugal pump works normally, the cavity should be filled with liquid. Before operation, there is a period of self-priming time, during which the air is continuously discharged to the pump body. This period belongs to partial idling.

Set the idle induction system. The water pump is monitored in real time by modern equipment. When the centrifugal pump runs idle, it will alarm immediately and stop automatically to protect the safety of the unit.

Notes for use attached:

Installation instructions:

1. During installation, the pipeline weight shall not be added to the water pump, and each support body shall be provided to prevent deformation from affecting the operation performance and life.

2. The pump and motor are of integral structure, so alignment is not required during installation, so installation is very convenient.

3. The anchor bolts must be tightened during installation to avoid the impact of vibration on pump performance during startup.

4. Before installing the water pump, carefully check whether there are hard objects (such as stones, iron particles, etc.) in the pump channel that affect the operation of the pump, so as to avoid damage to the impeller and pump body during the operation of the pump.

5. In order to facilitate maintenance and ensure safe use, a regulating valve shall be installed on the inlet and outlet pipelines of the pump and a pressure gauge shall be installed near the pump outlet to ensure the operation within the rated head and flow range, ensure the normal operation of the pump and increase the service life of the pump.

6. When the pump is used for suction, it should be equipped with a bottom valve, and the inlet pipeline should not have too many bends, and there should be no water or air leakage.

7. The discharge pipeline such as check valve shall be installed outside the gate valve.

8. When the pump shaft is moved after installation, the impeller shall be free of friction sound or seizure, or the pump shall be disassembled to check the cause.

9. The installation mode of pump is divided into rigid connection and flexible connection installation.

Centrifugal pump installation sequence:

1. When the unit is transported to the site, the water pump and motor have been calibrated by the person who attached the base. It is not necessary to remove the water pump and motor when leveling the base, so the installation is very convenient;

2. Place the base on the foundation, pad wedge iron near the foundation screw, and pad the base 20~40mm high for filling cement slurry after leveling;

3. Check the levelness of the base with a level gauge, fill the base with cement slurry after leveling, and check the levelness again after the cement dries up;

4. When the power of the unit is large, the pump, motor and base may be packaged separately to facilitate transportation. At this time, users need to install and calibrate the pump unit by themselves. The method is as follows:

a) Clean the dirt on the support plane of the base, the water pump foot and the motor foot plane, and place the water pump and motor on the base;

b) Adjust the level of the pump shaft, and fix the pump on the base with bolts after leveling to prevent it from moving;

c) Lift the motor, make the pump coupling and motor coupling cooperate, and put down the motor to the corresponding position on the base;

d) Adjust the gap between the two couplings to about 5mm, and correct whether the axis lines of the motor shaft and the pump shaft coincide. The method is to place a flat ruler on the coupling, and the outer circles of the two couplings should be flat with the flat ruler. If they do not coincide, adjust the relative position of the motor or the pump, or pad it with a thin iron sheet;

e) In order to check the installation accuracy, the clearance between two coupling planes shall be measured with a feeler gauge at several different positions on the circumference of the coupling. The difference between the maximum and minimum clearance around the coupling plane shall not exceed 0.3mm, and the difference between the lower or left and right centerlines at both ends shall not exceed 0.1mm.

5. When the unit is not equipped with a base, it needs to be directly installed on the foundation. The method is similar to that in 4., but more attention should be paid to calibration.

Start and stop:

Preparation before starting:

1. Turn the fan blade of the motor by hand. The impeller should be free of grinding and flexible.

2. Open the inlet valve, open the exhaust valve to fill the whole pump chamber with liquid, and then close the exhaust valve.

3. Turn the pump by hand to make the lubricating fluid enter the mechanical seal face.

4. Inch the motor to determine whether the steering is correct.

Start and operation:

1. Fully open the inlet valve and close the discharge pipeline valve.

2. Connect the power supply, and when the pump reaches the normal speed, gradually open the valve on the discharge pipeline and adjust it to the required working condition.

3. Pay attention to the reading of the instrument and check the leakage of the shaft seal. Under normal conditions, the mechanical seal leaks,<3 drops/minute. Check that the temperature rise at the motor and bearing is ≤=70 ° C. If any abnormality is found, it should be handled in time.

parking:

1. Gradually close the discharge pipeline valve and cut off the power supply.

2. Close the inlet valve.

3. If the ambient temperature is lower than 0 ℃, the liquid in the pump should be drained to avoid frost cracking.

4. If the pump is out of service for a long time, it should be disassembled, cleaned, packed and kept.

4. Pump maintenance

Maintenance during operation:

1. The water pipe must be highly sealed.

2. It is forbidden to operate the pump for a long time under cavitation.

3. Do not allow the motor to run for a long time in excess of current when the pump is running at flow.

4. Regularly check that when the pump is running, the motor runs for a long time due to overcurrent.

5. The pump shall be guarded by special personnel during operation to avoid accidents.

6. Add oil to the bearing every 500 hours of pump operation. Motor power greater than 11KW is equipped with oil filling device, which can be directly injected with high-pressure oil gun to ensure excellent bearing lubrication.

7. After long-term operation of the pump, if the noise and vibration of the unit increase due to mechanical wear, the pump should be stopped for inspection. If necessary, the vulnerable parts and bearings can be replaced. The overhaul period of the unit is generally one year.

Mechanical seal maintenance:

1. The mechanical seal lubrication shall be clean and free of solid particles.

2. It is strictly forbidden to operate the mechanical seal under dry grinding.

3. Before starting, the pump (motor) should be turned for several circles to prevent the seal ring from being broken and damaged due to sudden starting.

Overall maintenance:

1. Check whether the centrifugal pump pipeline and joint are loose. Rotate the centrifugal pump by hand to see if it is flexible.

2. Add bearing lubricating oil into the bearing body, observe that the oil level should be at the center line of the oil pointer, and the lubricating oil should be replaced or supplemented in time.

3. Unscrew the water diversion plug of the centrifugal pump body, and inject water (or slurry).

4. Close the gate valve, outlet pressure gauge and inlet vacuum gauge of the water outlet pipeline.

5. Inch the motor to see if the rotation direction of the motor is correct.

6. When the centrifugal pump operates normally, open the outlet pressure gauge and the inlet vacuum pump, and gradually open the gate valve, and check the motor load.

7. Try to control the flow and head of the centrifugal pump within the range indicated on the label to ensure that the centrifugal pump operates at the highest efficiency point, so as to obtain the maximum energy saving effect.

8. During the operation of centrifugal pump, the bearing temperature shall not exceed the ambient temperature by 35C, and the maximum temperature shall not exceed 80C.

9. In case of abnormal sound of centrifugal pump, stop the pump immediately to check the cause.

10. When the centrifugal pump is to be stopped, first close the gate valve and pressure gauge, and then stop the motor.

11. The lubricating oil of the centrifugal pump shall be replaced after 100 hours in the first month of operation, and then every 500 hours.

12. Regularly adjust the packing gland to ensure that the leakage in the packing chamber is normal (it is better to leak in drops).

13. Regularly check the wear condition of the shaft sleeve, and timely replace it if it is worn seriously.

14. When the centrifugal pump is used in cold winter, it is necessary to unscrew the drain plug at the lower part of the pump body to drain off the medium after shutdown. Prevent frost cracking.

15. If the centrifugal pump is out of service for a long time, it is necessary to disassemble all the pumps, wipe off the moisture, coat the rotating parts and joints with grease, and install them properly.