Causes of demagnetization of the inner and outer magnetic rotors in magnetic pumps and causes of sliding bearing damage

Reasons for demagnetization of the inner and outer magnetic rotors in magnetic pump: 1. Debris blocking the internal cooling/lubrication pipes can cause the temperatures of the inner and outer magnetic cylinders to rise rapidly; once these temperatures exceed 80 degrees, demagnetization may occur； 2. During maintenance, proper cleaning was not ensured; iron shavings adhered to the inner magnet, causing the isolation sleeve to wear out ； 3. The axial clearance between the inner rotor and the isolation sleeve is too small, resulting in friction and demagnetization. 4. Wear of the thrust bearing, resulting in friction between the inner rotor and the isolation sleeve ； 5. Medium temperature exceeds 80 degrees ； 6. During process purging, steam temperature causes demagnetization. Causes of sliding bearing damage: 1. Dry running caused by cavitation; 2. Ingression of contaminants, leading to bearing wear; 3. Alternating impacts caused by vibrations, resulting in bearing damage

The explanation on the 2nd floor is quite comprehensive. One additional point: another reason for demagnetization is dry operation, which can also lead to demagnetization

1. Problems caused by large fluctuations in the pump’s operating conditions: In actual operation, if the operating parameters (inlet pressure, outlet pressure) fluctuate significantly, it is easy to disrupt the hydraulic balance of the magnetic pump, causing the sliding bearings to experience large radial and axial forces that result in bearing damage. 2. Problems caused by cavitation in pumps: The main reasons for cavitation in pumps include high resistance in the pump inlet pipe, a high gas content in the fluid being transported, insufficient priming of the pump, and insufficient energy head at the pump inlet. Cavitation is the most harmful to pumps. When cavitation occurs, the pump vibrates violently and hydraulic balance is severely disrupted, which can lead to damage to the pump bearings, rotor, or impeller. 3. No medium or low flow rate of the conveying medium: This causes dry friction in the bearing, leading to its burning and destruction. The Hammett magnetic pump uses the medium being transported to provide lubrication and cooling for the sliding bearings; in the absence of an inlet valve or an outlet valve, these sliding bearings get damaged due to the lack of lubrication and cooling from the transported medium. ) Damage to the magnetic pump bearings. The bearings of the CQB magnetic pump are made of high-density carbon; if the pump runs out of water or if there are impurities inside the pump, this can cause damage to the bearings. If the coaxiality requirement between the inner and outer magnetic rotors of a cylindrical coupling is not ensured, it will also directly affect the lifespan of the bearings. 4. The shaft of the magnetic pump broke. The pump shaft of the CQB type magnetic pump is made of 99% alumina ceramic. The main reason for the shaft breaking is that the pump operated without liquid, causing the bearings to grind dry and thus twisting the shaft. When the pump is disassembled for inspection, it can be seen that the bearings are severely worn. The main way to prevent the pump from breaking is to avoid running it without any liquid. 5. The magnetic pump fails to discharge liquid. The inability of a magnetic pump to deliver liquid is one of the most common faults in water pumps, and there are various reasons for this. First, check whether there are any air leaks in the pump’s suction line, ensure that any air in the suction line has been removed, verify that the amount of liquid filled in the magnetic pump is sufficient, and check for any obstructions in the suction line. It is also necessary to determine whether the pump is running in reverse (especially after replacing the motor or after repairing the power supply circuit). Additionally, pay attention to whether the suction height of the water pump is too high. If the problem remains unresolved after the above checks, the pump can be disassembled to check whether the pump shaft is broken; it is also necessary to verify that the rotating and stationary rings of the pump are in good condition, as well as whether the entire rotor can move slightly axially. If axial movement is difficult, check whether the carbon bearing is too tightly fitted to the water pump shaft. 6. Damage to the isolation sleeve: The magnetic coupling is cooled by the medium pumped by the pump; if there are hard particles in this medium, it can easily cause scratches or punctures in the isolation sleeve. Sometimes, improper maintenance methods can also lead to damage to the isolation sleeve.