Although magnetic vane pumps have advantages such as no leakage and corrosion resistance, they have obvious deficiencies in terms of efficiency, medium adaptability, manufacturing cost, power and head, temperature control, installation accuracy, cavitation risk and maintenance cost, as follows:
Low efficiency
During the magnetic drive process, there is energy loss when the magnetic field transmits torque, resulting in the overall efficiency of the pump being lower than that of ordinary centrifugal pumps. This increases energy consumption and raises long-term operating costs, especially in scenarios where efficient transportation is required.
It has high requirements for the cleanliness of the medium
Magnetic vane pumps are extremely sensitive to the cleanliness of the conveyed medium. If the medium contains impurities, hard particles or magnetic substances, it is easy to cause wear of the magnetic steel, scratches on the isolation sleeve, and even lead to the jamming of the inner rotor or local demagnetization. For instance, when transporting magnetic pulp containing iron filings, permanent magnets may fail due to interference from foreign magnetic substances.
The manufacturing cost is relatively high
Magnetic vane pumps use magnetic materials (such as neodymium iron boron) and isolation sleeves made by special processes, which results in their manufacturing costs being significantly higher than those of ordinary pumps. Under the same flow rate and head parameters, the purchase price of magnetic vane pumps is usually 2 to 3 times that of ordinary centrifugal pumps, increasing the initial investment pressure.
The power and head are limited
Due to the limitation of magnetic force transmission capacity, the power and head range of magnetic vane pumps are relatively small, making it difficult to meet the requirements of large flow and high head working conditions. For instance, when it is necessary to transport high-viscosity media such as asphalt, the magnetic pump may cause the inner and outer magnetic rotors to lose step due to the decline of magnetic force, which affects the conveying efficiency.
Strict temperature limit
The magnetic coupling transmission part of the magnetic vane pump is sensitive to temperature. High temperatures may cause the magnetic properties of permanent magnets to decline, while low temperatures may affect the material’s performance. Domestic magnetic pumps are generally only suitable for transporting media below 100℃ and 1.6Mpa. Beyond this range, additional cooling or heating devices need to be configured, which increases costs.
The installation accuracy requirement is high
The alignment accuracy of the coupling of the magnetic vane pump is strictly required. If the alignment is improper, it may lead to damage of the bearings at the inlet, wear of the isolation sleeve, and even cause vibration and noise problems. For instance, a certain food factory’s magnetic transmission system wore out prematurely due to installation negligence, and the bearings were replaced twice within three months.
It is prone to gas erosion
When transporting liquids containing dissolved gases, magnetic vane pumps are prone to cavitation. Cavitation can reduce the performance of pumps, accelerate the damage of internal parts and shorten the service life of equipment. For instance, the magnetic pump used by a certain brewery to transport fermentation liquid had numerous holes on the impeller surface due to cavitation, and its actual service life was far lower than the designed value.
The maintenance cost is relatively high
The maintenance of magnetic vane pumps is difficult and time-consuming. Disassembling the isolation sleeve and the inner and outer magnetic rotors requires professional tools and techniques, and the maintenance time may be several times that of a common centrifugal pump. In the event of an emergency malfunction, it may lead to a prolonged shutdown of the production line, increasing indirect losses.