What is a magnetic drive pump? What is the principle of magnetic pump water pump?

What is a magnetic drive pump?

The magnetic pump is a branch of the water pump field. It is a new product that applies the working principle of a permanent magnetic coupling to a centrifugal pump. The magnetic pump consists of three parts: a pump, a magnetic transmission, and a motor. The magnetic transmission of the magnetic pump consists of an outer magnetic rotor, an inner magnetic rotor, and a non-magnetic isolation sleeve. When the motor drives the outer magnetic rotor to rotate, the magnetic field can penetrate the air gap and non-magnetic materials, driving the inner magnetic rotor connected to the impeller to rotate synchronously, realizing contactless synchronous transmission of power, and converting the dynamic sealing structure that is prone to leakage into a static sealing structure with zero leakage. Since the sliding bearings of the magnetic pump are lubricated with the medium being transported, different materials should be selected to make the bearings according to different media and operating conditions.

Principle of magnetic pump water pump

A water pump is a machine for conveying liquid or pressurizing liquid. It transfers the mechanical energy of the prime mover or other external energy to the liquid to increase the energy of the liquid. It is mainly used to convey liquids including water, oil, acid and alkali liquids, emulsions, suspensions and liquid metals, etc. It can also convey liquids, gas mixtures and liquids containing suspended solids. The technical parameters for measuring the performance of water pumps include flow rate, suction head, head, shaft power, water power, efficiency, etc.; according to different working principles, it can be divided into positive displacement water pumps, vane pumps and other types. Positive displacement pumps use the change of the volume of their working chambers to transfer energy; vane pumps use the interaction between the rotating blades and water to transfer energy, and there are centrifugal pumps, axial flow pumps and mixed flow pumps. Centrifugal pumps can be divided into AC water pumps, brushed DC water pumps, brushless DC motor water pumps, and brushless DC magnetic isolation water pumps according to the control principle.

Advantages and disadvantages of magnetic pumps

  1. Advantages

The advantages of magnetic drive centrifugal pumps include: no leakage at all, a large gap between the inner and outer rotors, a thickness of no more than 8mm when using a non-metallic isolation sleeve, and a thickness of no more than 5mm when using a metal isolation sleeve. The wall thickness of the isolation sleeve is large, and the isolation sleeve is less likely to be worn through. The gap between the isolation sleeve and the inner and outer magnetic rotors is also large. The magnetic centrifugal pump operates reliably, and the possibility of wear between the inner magnetic rotor and the isolation sleeve caused by shaft seal wear is small. The isolation sleeve is easy to disassemble and can be replaced on site, which is convenient for maintenance. It can be applied to SIC bearings, has good wear resistance, long service life, and the pump speed is not limited by the motor. It can be different from the motor speed. In addition, the magnetic centrifugal pump has the following advantages:

  1. Since the drive shaft of the magnetic centrifugal pump does not need to penetrate the pump casing, it uses the magnetic field to transmit torque through the magnetic field and the thin wall of the isolation sleeve to drive the inner magnetic rotor, thereby fundamentally eliminating the leakage channel of the shaft seal and achieving complete sealing.
  2. The magnetic drive pump has an overload protection function when transmitting power.
  3. Except for the high requirements for magnetic materials and magnetic circuit design of magnetic pumps, the technical requirements for other parts are not high.
  4. The maintenance and repair workload of magnetic drive pumps is small.


  1. The efficiency of magnetic centrifugal pumps is lower than that of ordinary centrifugal pumps. They cannot operate at a flow rate of 30% of the rated flow rate, and idling is even more taboo.
  2. Since the wear resistance of the isolation sleeve material of magnetic centrifugal pumps is generally poor, magnetic pumps are generally used to transport media with unstable solid particles and magnetic particles are strictly prohibited from entering the pump.
  3. Magnetic centrifugal pumps of general structure are allowed to transport liquids containing solid particles with a diameter of less than 0.15mm and a mass fraction of no more than 5% (auxiliary systems are required when exceeding).
  4. The pump and the motor are connected by a coupling. The coupling requires high precision for the installation of the center line. If the centering is not correct, it will cause damage to the bearing at the inlet and wear of the isolation sleeve to prevent single-sided leakage.
  5. The magnetic drive of the magnetic centrifugal pump has two modes: synchronous transmission and asynchronous transmission. The inner and outer magnetic rotors of the synchronous transmission are equipped with permanent magnets, so the temperature of the conveyed liquid must be lower than the maximum temperature allowed by the permanent magnet. A certain amount of surplus must be left. Although cobalt and samarium permanent magnets can reach 350 degrees Celsius, the actual use temperature generally does not exceed 260 degrees Celsius, otherwise high temperature may cause permanent magnet demagnetization. The magnetic pump with special structure can reach up to 450 degrees Celsius.
  6. The magnetic centrifugal pump has high requirements on the material and manufacturing process of the isolation sleeve. If the material is not properly selected or the manufacturing quality is poor, the isolation sleeve will not withstand the wear of the inner and outer magnetic rotors and will wear out. Once it breaks, the conveyed medium will overflow, causing equipment failure and affecting the normal operation of the device.
  7. When the temperature of the medium transported by the magnetic centrifugal pump exceeds the specified value, external cooling is required, such as setting up a heat-insulating cavity, injecting coolant with a pressure higher than the sealing pressure into the pump cavity to cool the internal magnetic rotor and bearings. Alternatively, an isolation sleeve with an interlayer can be used, and coolant can be passed through the interlayer, or a cooling jacket and cooling coil can be set on the pump body. However, the structure is complex and the cost is high.