Problems with magnetic pump idling

At high speeds, the external and internal magnets continuously cut through the magnetic flux lines, generating a large amount of heat. The high temperature inside the pump chamber cannot be dissipated, and once a certain temperature is reached, the magnets lose their magnetism

Reply to 2# awfuling: What you mean is that if there’s a fluid present, it can carry away heat, thus creating a positive cycle, right? Could such a situation occur with shielded pumps as well?

Reply to 3# formosapta: Magnetic drive pump cooling system: When the magnetic drive is in operation, eddy currents continuously generate heat, so it is necessary to design a cooling system that can continuously remove this heat. If heat is not removed, the temperature will rise rapidly, affecting the driving torque and even causing demagnetization. The cooling liquid used to carry away heat is usually a medium pumped, and these media have a certain impact on the efficiency of the pump. For pumps with high flow rates, the cooling medium has a minor impact on the pump’s efficiency. In contrast, for pumps with low flow rates, especially those with high head at low flow rates, the cooling medium has a significant effect on the pump’s efficiency. If the pump runs idle (while still filled with fluid), the heat generated by eddy currents cannot be dissipated, causing the temperature to rise rapidly, which poses an even greater risk.

Reply to 3# formosapta: The flow channel of the shielded pump is long, which results in slow heat dissipation; therefore, an external cooling device is needed. Shielded pumps are also driven by electromagnetic fields, and with the motor located inside the pump chamber, a large amount of heat is generated. So it’s easy to burn out the motor. Of course, the harm caused by the idle operation of a shielded pump is much less than that of a magnetic pump

Cage pumps must never be run dry; their sliding bearings rely on the self-lubrication of the medium. Magnetic pump running idle: 1. High temperature leading to demagnetization; 2. Self-lubrication issues with the bearings.

Due to structural limitations, conventional magnetic pumps, both domestic and international, are not allowed to operate without a medium. The heat generated by relative friction in sliding bearings during operation, as well as the magnetic eddy current heat resulting from the torque transmission through magnetic couplings, must be dissipated through the circulation of a medium. Therefore, magnetic pumps generally cannot operate without a medium. However, the German company Kraus has proposed using rolling bearings made of zirconia ceramic, which do not require lubrication during operation. Additionally, they have replaced the isolation sleeves with non-metallic materials, eliminating eddy current losses; as a result, it is possible for magnetic pumps to operate without a load. I would like to hear everyone’s opinions on this – please share your insights!