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There are so few things you need to know about the magnetic pump!
Time:2022-03-18 Cilck:158
There is no dynamic seal and no leakage, which is the outstanding feature of magnetic pump.

Magnetic pump is widely used in the production process of petroleum, chemical, pharmaceutical, printing and dyeing, electroplating, food, environmental protection and other enterprises to transport corrosive liquids without iron filings, especially for the transportation of flammable, explosive, volatile, toxic and precious liquids.

In addition, shielded pumps also have the feature of no leakage, so finally, I'll compare the difference between the two.

Magnetic pump

1. Transmission principle
The full name of magnetic pump is magnetic drive centrifugal pump, which transmits torque in a contactless way. When the motor drives the outer rotor (i.e. outer magnetic steel) assembly to rotate, through the action of magnetic field, the magnetic line of force passes through the isolation sleeve to drive the inner rotor (i.e. inner magnetic steel) assembly and impeller to rotate synchronously, and the medium is enclosed in the static isolation sleeve, so as to achieve the purpose of pumping medium without leakage and completely solve the shaft seal leakage of mechanical drive pump.
Because the liquid is enclosed in a static isolation sleeve, it is a fully sealed and leak free pump type.

2. Structure
Magnetic pump mainly includes motor, support, outer magnetic cylinder (driving rotor), inner magnetic cylinder (driven rotor), isolation cover, sliding bearing, transmission shaft, impeller and pump body.
Among them, the magnetic coupling for pump drive is composed of inner magnetic cylinder, outer magnetic cylinder, isolation cover and magnetic body, which is also called permanent magnetic coupling and magnetic coupling.

Inner magnetic cylinder

The inner magnetic cylinder and the pump rotor are coaxial, and permanent magnetic blocks are installed in the direction parallel to the axial direction. The magnetic blocks are isolated by stainless steel and other materials for magnetic isolation (reducing transverse magnetic leakage) and support protection. In order to protect the magnetic blocks on the inner magnetic cylinder, a layer of protective materials (such as plastic, stainless steel, etc.) is generally covered on the outer surface of the inner magnetic cylinder.

External magnetic cylinder

The outer magnetic cylinder is connected with the motor. Similarly, a magnetic block is installed on the cylindrical surface of the outer magnetic cylinder, and the magnetic blocks are isolated and supported by magnetic isolation materials. Generally, the outer magnetic cylinder will not be added with a protective sleeve (it will not contact with the medium).

Isolation cover

The isolation cover is located between the inner and outer magnetic cylinders and fixed with the pump body with certain measures to form a closed cavity. The main materials of the isolation cover are stainless steel, titanium alloy, plastic, carbon fiber, ceramics and other materials.

The isolation sleeve is a very important part of the magnetic pump. Because of its combination with the pump body, inner and outer magnetic cylinders, there is no need for power seal components to achieve real 0 leakage.

Bearing components

The pump end adopts sliding bearing structure, and the main materials are graphite, silicon carbide, polytetrafluoroethylene, etc. The driving end adopts deep groove ball bearing, angular contact ball bearing, etc.


Magnetic body


Magnetic body is the main component of torque transmission. Its quality directly affects the service life and efficiency of magnetic pump, that is, transmitting torque. At present, ferrite, rare thorium cobalt and neodymium iron boron are widely used in China.

3. Characteristics
Magnetic pump cancels the mechanical seal of the pump and completely eliminates the disadvantages of mechanical seal centrifugal pump, dripping and leakage. It is the best choice for leak free factory. Because the overflow parts of the pump are made of stainless steel and engineering plastics, the purpose of corrosion resistance is achieved. The magnetic coupling of the pump is integrated with the pump body, so it has the advantages of compact structure, convenient maintenance, safety and energy saving. The magnetic of the pump inevitably runs and runs, and the coupling can play the role of overload protection for the transmission motor.

4. Working conditions
The viscosity of the medium conveyed by the magnetic pump shall not be greater than 30 × 10-6m3 / s liquid without ferromagnetism and fiber.
For the rated temperature of conventional magnetic pump, for the pump body made of metal or F46 lining, the maximum working temperature is 100 ℃ and the rated pressure is 1.6Mpa; Service temperature of high temperature magnetic pump ≤ 350 ℃; For the pump body made of non-metallic material, the maximum temperature shall not exceed 100 ℃, the rated pressure shall be 1.6Mpa, and the non-metallic material shall be selected with high temperature resistant configuration if it exceeds 100 ℃.
For liquids with medium density greater than 1600kg / m3, the magnetic coupling shall be designed separately. The bearing of the magnetic pump is lubricated and cooled by the transmitted medium. Generally, no-load operation of the magnetic pump is strictly prohibited.

Similarities and differences with shielded pump

The two pumps are widely used in chemical, pharmaceutical, nuclear industry, aerospace and other devices. In terms of domestic application, shielded pump is still the mainstream, mainly because the domestic magnetic steel material technology is not qualified, which often leads to accidents such as demagnetization, heating and overload of magnetic pump, but the application of magnetic pump in foreign countries is still very mature.

What magnetic pump and shield pump have in common: they are leak free pumps without any shaft seals.

The difference between magnetic pump and shield pump: the structural principle is completely different.

◆ the shielded pump directly uses the principle of the motor, and the energy consumption of the magnetic pump motor should be transmitted to the impeller through the internal and external magnetic steel (part of the energy is converted into the heating of the magnetic steel). Therefore, the efficiency of the shielded pump is higher than that of the magnetic pump theoretically.

◆ it can be seen from the structure that the biggest disadvantage of the canned motor pump is that it cannot be repaired (very difficult). In the process of use, whether there is a problem with the pump body or motor, the user can basically not repair it by himself.

The repair of magnetic pump is not much different from that of ordinary pump. The motor bearing of shield pump is in contact with the medium, which is difficult to maintain and repair. The fault of the bearing can not be detected, and the fault phenomenon and omen can not be observed. It is difficult to find the hidden danger in operation. Once there is a problem, it is fatal damage.

◆ the thickness of the isolation sleeve of the magnetic pump is more than 3 times that of the shielded pump, so the tightness and reliability are more guaranteed.

◆ the heat in the motor is taken away by the cooling medium in the bearing of the motor, which is not lubricated by the motor. This leads to a high failure rate of this shielded motor. Magnetic pump motor is an ordinary motor, which is cooled by fan, mature and reliable. But also because of this, the noise of magnetic pump is greater than that of shielded pump.

◆ the structure of the shielded pump is more compact, so it is smaller than the magnetic pump and saves space.

◆ the shield pump has no coupling, and the magnetic pump is connected with the motor through the coupling, which needs to be aligned.

◆ due to the problem of magnetic material, the maximum power of magnetic pump is lower than that of shielded pump, which leads to the limitation of magnetic pump in some large load applications caused by high flow and high pressure.

◆ the magnetic pump is more suitable for highly corrosive media than the shielded pump because its isolation sleeve is thicker (the thicker the shielded sleeve of the shielded pump will affect the electromagnetic effect of stator winding and rotor winding).

◆ magnetic pump cannot be used when the medium contains metal particles (such as iron filings), because ferromagnetic materials will be attracted by magnetic steel, resulting in failure. The shielded pump can handle.