Advantages of magnetic
pump:
1. Since the drive shaft of the magnetic pump does not need to
penetrate the pump casing, but uses the magnetic field to drive the inner
magnetic rotor through the magnetic field and the thin-walled transmission
torque of the isolation sleeve, thus fundamentally eliminating the leakage
channel of the shaft seal and achieving complete sealing.
2. The magnetic
pump has overload protection when transmitting power.
3. The magnetic
material and magnetic circuit design of the magnetic pump have high
requirements, while the other parts have low technical requirements.
4. The
maintenance and overhaul workload of magnetic pump is small.
Disadvantages of
magnetic pump:
1. The efficiency of the magnetic pump is lower than that of
the ordinary centrifugal pump, and it cannot operate at 30% of the lower rated
flow, and it is more forbidden to idle.
2. Due to the poor wear resistance of
the isolation sleeve material of the magnetic pump, the magnetic pump is
generally used to transport the medium without solid particles and the magnetic
particle material is forbidden to enter the pump.
3. The magnetic pump with
general structure is allowed to transport the liquid containing solid particles
with diameter less than 0.15mm (100 mesh) and mass fraction less than 5%
(auxiliary system shall be added when exceeding).
4. The pump and motor are
connected by a coupling. The coupling requires a high accuracy for the
installation of the center line. Improper alignment will lead to the damage of
the bearing at the inlet and the wear of the isolation sleeve against unilateral
side leakage.
5. The magnetic drive of the magnetic pump has two modes:
synchronous drive and asynchronous drive. The inner and outer magnetic rotors of
the synchronous drive are equipped with permanent magnets, so the temperature of
the liquid transported must be lower than the allowable temperature of the
permanent magnet. A certain margin must be reserved. Although cobalt and
samarium permanent magnets can reach 350 degrees Celsius, the actual use
temperature generally does not exceed 260 degrees Celsius. High temperature on
the other side may cause permanent magnet loss of magnetism. The magnetic pump
with special structure can reach 450 degrees Celsius.
6. The magnetic pump
has high requirements for the material and manufacturing process of the
isolation sleeve. If the material is not selected properly or the manufacturing
quality is poor, the isolation sleeve cannot withstand the wear of the inner and
outer magnetic rotors, resulting in wear. Once it breaks, the medium conveyed
will overflow, causing equipment failure and affecting the normal operation of
the device.
7. When the temperature of the medium conveyed by the magnetic
pump exceeds the specified value, it is necessary to provide cooling outside.
For example, the heat insulation chamber is set, the pump chamber is filled with
coolant with a pressure higher than the sealing pressure, and the inner magnetic
rotor and bearing are cooled. The isolation sleeve with a interlayer can also be
used. The interlayer is filled with coolant, or the pump body is equipped with a
cooling jacket and a cooling coil. The single structure is complex and the cost
is high.
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