Common faults and troubleshooting of magnetic drive pump

Common faults and troubleshooting of magnetic drive pump common faults of magnetic drive pump in the process of use: damaged bearing of magnetic drive pump, broken shaft of magnetic drive pump, lack of flow, lack of head, and inability of magnetic drive pump to pump liquid.

20210822065649 52387 - Common faults and troubleshooting of magnetic drive pump

1. Magnetic drive pump bearing damaged
The bearing of magnetic drive pump adopts high-density carbon. If the pump is cut off or there are impurities in the pump, the bearing will be damaged. If the coaxiality between the inner and outer magnetic rotors of the cylindrical coupling is not guaranteed, it will also directly affect the service life of the bearing.
2. Magnetic drive pump shaft broken
The data of the pump shaft of the magnetic drive pump is 99% alumina porcelain. The main reason for the fracture of the pump shaft is that the shaft is twisted due to the empty operation of the pump and the dry grinding of the bearing. When the pump is disassembled for inspection, it can be seen that the bearing has been seriously worn. The main method to prevent the pump from breaking is to prevent the pump from idling.
3. Lack of flow
The main reasons for the lack of flow are: the impeller is damaged, the speed is not enough, the head is too high, and there are sundries in the pipe.
4. Lack of head
The reasons for the lack of head are: there is air in the escort medium, the impeller is damaged, the speed is not enough, the specific gravity of the escort liquid is too large, and the flow is too large.
5. The magnetic drive pump cannot pump out liquid
The most common problem of magnetic drive pump is that it can’t pump liquid, and there are many reasons. First, check whether there is air leakage in the suction pipe of the pump, whether the air in the suction pipe can be discharged, whether the amount of liquid filled in the magnetic drive pump is sufficient, and whether there are sundries in the suction pipe. Also check whether the pump is reversed (especially after changing the motor or after the maintenance of the power supply line). Pay attention to whether the suction height of the pump is too high. If it cannot be handled after the above inspection, the pump can be disassembled for inspection to see whether the pump shaft is broken, whether the moving ring and static ring of the pump are intact, and whether the whole rotor can move a small amount axially. If the axial movement is difficult, check whether the carbon bearing can be separated from the pump shaft too tightly.
If the magnetic drive pump is repaired several times and no problem is found, pay attention to whether the magnetic coupling works normally. The bearing, inner magnetic rotor and spacer sleeve will generate heat during operation, which will increase the working temperature. On the one hand, it will reduce the transmitted power, and on the other hand, it will take a lot of trouble to escort the magnetic pump that is easy to vaporize liquid. The power transmitted by magnetic steel is a continuous falling curve with the increase of temperature. Generally, below the working limit temperature of magnetic steel, the decline of transmission ability is reversible, while above the limit temperature, it is irreversible, that is, after the magnetic steel is cooled, the lost transmission ability can no longer be recovered. Under special conditions, when the magnetic coupling slips (out of step), the eddy current heat in the spacer will increase sharply and the temperature will rise sharply. If it is not handled in time, it will cause demagnetization of the magnetic steel and make the magnetic coupling invalid.
Therefore, the magnetic drive pump should be designed with a reliable cooling system. For the medium that is not easy to vaporize, the cooling circulation system usually leads out the liquid flow from the impeller outlet or pump outlet and returns to the suction population through the bearing and magnetic drive. For the medium that is easy to vaporize, a heat exchanger shall be added or the liquid flow shall be led to the storage tank outside the pump to prevent the heat from returning to the suction population. For the medium with solid impurities or ferromagnetic impurities, filtration shall be considered, and for the high-temperature medium, cooling shall be considered, To ensure that the magnetic coupling does not exceed the working limit temperature.

When considering whether the rotation speed is enough, first check whether the rotation speed of the motor itself is normal, and stop measuring with the tachometer. When the rotation speed of the motor is normal, check whether there will be slippage of the magnetic coupling.

Source: China Permanent Magnet Manufacturer – www.ymagnet.com

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