Failure analysis and protection measures for magnetic pumps(1)

The main reason for the breakage of the pump shaft is that the shaft is twisted off because the pump is airborne and the bearings are dry-wearing. When the pump is dismantled and inspected, it can be seen that the bearing has been badly worn. The main way to prevent the pump from breaking is to avoid the pump from running in air.

(2) magnetic pump bearing damage. tc magnetic pump bearing using the material is high-density carbon, such as in case of pump broken water or pump impurities, will cause damage to the bearing. Cylindrical coupling inside and outside the magnetic rotor coaxiality requirements if not guaranteed, will also directly affect the life of the bearing.

(3) magnetic pump can not play the liquid. Magnetic pump can not play the liquid is the most prone to failure of the pump, and its causes are more. First of all, the pump should be checked whether there is a leak in the inhalation pipeline, check whether the air in the inhalation pipe is discharged, whether the amount of liquid filled in the magnetic pump is sufficient, whether the inhalation pipe is clogged with debris, should also check whether the pump is reversed (especially after changing the motor or power supply line overhaul), should also pay attention to the pump's suction height is too high. Through the above check if still can not be solved, the pump can be disassembled to check whether the pump shaft is broken, should also check the pump dynamic ring, static ring is intact, the whole rotor can be a small amount of axial movement. If axial movement is difficult, check whether the charcoal bearing is too tightly combined with the pump shaft.

It is worth noting that the magnetic pump can not be repaired several times to find out the problem, should pay attention to the magnetic coupling work is normal. The bearings, the inner magnetic rotor and the spacer will generate heat during operation, which will raise the working temperature and make the transmitted power drop on the one hand, and on the other hand will cause great trouble to the magnetic pump that conveys easily vaporized liquid. The power transferred by the magnet with the rise of temperature is a continuous decreasing curve, usually, below the working limit temperature of the magnet, the decrease of its transfer capacity is reversible, while above the limit temperature is irreversible, that is, after the magnet cools, the lost transfer capacity can never be restored. 

In special cases, when the magnetic coupling slips (loses step), the eddy current heat in the spacer will grow sharply and the temperature will rise sharply, which will cause the magnet to demagnetise and make the magnetic coupling fail if not dealt with in time. Therefore the magnetic pump should be designed with a reliable cooling system. For the medium that is not easy to vaporize, the cooling circulation system generally leads from the impeller outlet or pump outlet to the liquid flow, through the bearing and magnetic drive part back to the suction population, for the medium that is easy to vaporize, the heat exchanger should be increased or the liquid flow should be led to the storage tank outside the pump to avoid the heat back to the suction population, for the medium that has solid impurities or ferromagnetic impurities, filtration should be considered, for the high temperature medium, cooling should be considered to ensure that the magnetic coupling does not exceed the working limit temperature.

When considering whether the rotational speed is sufficient, first check whether the rotational speed of the motor itself is normal, which can be measured by a tachometer. In the case of normal rotational speed of the motor, consideration can be given to whether the magnetic coupling will slip off.

(4) Insufficient head. The causes of this fault are: air in the conveying medium, damage to the impeller, insufficient rotational speed, excessive specific gravity of the conveying liquid and excessive flow.

(5) Insufficient flow. The main causes of insufficient flow are: impeller damage, insufficient speed, too high head, blockage of debris in the pipe, etc.