Causes and solutions for fluoroplastic magnetic pump failing to deliver fluid:
The fluoroplastic magnetic pump fails to deliver fluid. This is a common fault of such pumps, and there are many possible causes. First, check if there is any air leakage in the suction pipeline, whether the air in the suction pipe has been discharged, whether the amount of fluid filled in the fluoroplastic magnetic pump is sufficient, and if there is any debris blocking the suction pipe. It is also necessary to check if the pump is running in reverse (especially after motor replacement or power supply line maintenance), and pay attention to whether the pump’s suction lift is too high. If the problem is not resolved after the above checks, the pump can be disassembled to inspect if the pump shaft is broken, check the condition of the pump’s moving ring and stationary ring, and whether the entire rotor can move slightly axially. If axial movement is difficult, check if the carbon bearing is too tightly coupled with the pump shaft.
It is worth noting that if the problem cannot be identified after several repairs of the fluoroplastic magnetic pump, attention should be paid to the normal operation of the magnetic coupling. Bearings, inner magnetic rotor and spacer sleeve will generate heat during operation, which will increase the working temperature. On the one hand, this reduces the transmitted power; on the other hand, it will cause great troubles for the fluoroplastic magnetic pump transporting easily vaporizable fluids. The power transmitted by the magnetic steel shows a continuous downward curve with the increase of temperature. Usually, below the maximum working temperature of the magnetic steel, the decrease in transmission capacity is reversible; however, above the maximum temperature, it is irreversible. That is to say, after the magnetic steel cools down, the lost transmission capacity can no longer be restored. For example, when the temperature of the high-temperature medium exceeds 90°C, high-grade magnetic steel and imported fluoroplastic (PFA) should be selected.
In special cases, when the magnetic coupling slips (loses synchronization), the eddy current heat in the spacer sleeve will increase sharply, and the temperature will rise rapidly. If not handled in time, it will cause demagnetization of the magnetic steel and failure of the magnetic coupling.
Therefore, the fluoroplastic magnetic pump should be designed with a reliable cooling system. For non-easily vaporizable media, the cooling circulation system generally draws fluid from the impeller outlet or pump outlet, passes through the bearings and magnetic transmission part, and returns to the suction port. For easily vaporizable media, an additional heat exchanger should be installed or the fluid should be directed to an external storage tank to avoid heat returning to the suction port. For media containing solid impurities or ferromagnetic impurities, filtration should be considered; for high-temperature media, cooling should be considered to ensure that the magnetic coupling does not exceed the maximum working temperature.
When checking whether the rotational speed is sufficient, first confirm that the rotational speed of the motor itself is normal (a tachometer can be used for measurement). If the motor speed is normal, consider the possibility of slipping of the magnetic coupling.
