During the use of magnetic drive pump, some users reported that the magnetic steel was demagnetized, which caused the pump to fail to operate normally. Therefore, they considered that the quality of the magnetic steel was a problem. However, after many years of experience accumulated from after-sales practice, we found that there are some problems in the early design or later use of the user, which led to the demagnetization of the magnetic steel. Therefore, in order to reduce the user's cost of use and avoid unnecessary losses, today we will talk about several reasons for demagnetization of magnetic steel.
1. The operating temperature is unreasonable. The temperature of the medium conveyed by the pump is too high, exceeding the allowable operating temperature of the magnetic material. For example, for a pump using NdFeB magnets, the operating temperature should be less than 150°C. If the system temperature exceeds 150°C, the magnets will be demagnetized quickly.
2. Long-term operation with head value lower than rated . For example, the rated point flow is 25 m3/h and the lift is 50m. If the operation deviates from the rated point (for example, the lift is only more than 10 meters), the internal return pressure of the pump will drop, the circulation will not be smooth, and the metal isolation sleeve eddy current heat will not go away, and its temperature will rise sharply. Magnets will also demagnetize.
3. The pipeline matching is unreasonable. For example, the inlet is required to be equipped with DN65 pipeline. If the pipeline is less than 65mm, the flow will be in short supply, which will easily cause poor internal circulation, heat is not easily taken away, and the system temperature exceeds the operating temperature of the magnet steel.
4. The sliding bearing is worn and not replaced in time. If it is not replaced in time, there will be friction between the inner magnetic rotor and the inner wall of the isolation sleeve, causing the temperature of the isolation sleeve to rise and the magnet steel to demagnetize.
5. The magnetic pump runs without liquid. In this case, the temperature of the metal isolation sleeve and the inner magnetic rotor rises sharply, exceeding the operating temperature of the magnetic steel, which will quickly lead to the demagnetization of the magnetic steel of the inner magnetic rotor.
6. The pump inlet and outlet lines are blocked. In this case, the magnetic pump will work without liquid or less liquid, and the internal circulation of the pump will be affected. So the temperature will rise; and the blockage of the outlet pipeline will also cause the magnet steel to demagnetize due to the poor circulation in the pump. If the pump inlet pipeline is equipped with a filter, the filter should be cleaned regularly to ensure that the filter area is within a reasonable range.
7. The rotor parts are abnormally stuck. The rotor part consisting of the inner magnet and the impeller is stuck by mechanical impurities and cannot run, but the motor does not stop in time, which will lead to demagnetization of the magnetic steel.
8. Cavitation phenomenon. The cavitation phenomenon of the pump will cause the demagnetization of the magnetic steel for various reasons.
From the above reasons, we can see that temperature is the main reason that affects the demagnetization of magnetic steel. In order to give you a understanding of the influence of temperature on the magnetic torque strength, please look at the line graph below.
