Magnetic pump

Direct connection is better; abnormal concentricity can cause problems.

The operating temperature for direct connection is lower； Coupled connections can be used at high temperatures, and they facilitate shaft turning; the motor does not need to be moved during maintenance.

This post was last edited by 3983596_FPPZ on 2018-11-17 at 10:13. Direct connection: suitable for low-power, stable operating conditions. Advantages: 1. The external magnetic rotor is positioned using a shoulder, so there is no need to align the motor and the pump axially. 2. It has a small size, which helps reduce the space required for installation in situations where space is limited. 3. The cost is low; the pump does not require bearing suspensions to support the external magnetic rotor, and it has no couplings or coupling guards. The base is small, and the pump lacks additional support feet. Disadvantages: 1. The external magnetic rotor is fixed to the motor shaft, meaning the motor bearings have to bear the forces exerted by the rotor (axial and radial forces). This increases the load on the bearings, shortens their lifespan, and makes them more prone to damage. 2. It is difficult to disassemble the pump for maintenance; the motor must be moved in order to do so, which is problematic for pumps that suffer from frequent damage due to unstable operating conditions. 3. It is hard to determine the rotation direction of the pump, as it is not possible to rotate the pump manually. In some cases, the rotation direction is determined by using the motor fan, while in others, observation holes are provided in the brackets connecting the motor and the pump. 4. When assembling or disassembling the pump, significant axial forces are generated when aligning the external and internal magnetic rotors, which can cause the external magnetic rotor to shift axially. Therefore, reliable axial positioning of the external magnetic rotor is necessary. However, practical conditions make it difficult to achieve axial positioning of the external magnetic rotor; for example, drilling holes in the motor shaft is not easy to do, and if set screws are used for positioning, the positioning force is insufficient. Direct-connected pumps and non-direct-connected pumps have advantages and disadvantages that complement each other. Non-direct-connected pumps are suitable for high-power applications, those with complex operating conditions, and situations where the pump is prone to damage. Advantages include: 1. The external magnetic rotor is fixed on a separate bearing bracket, so the motor bearings do not need to bear any load. 2. It is easier to maintain and disassemble such pumps compared to directly-connected pumps; the pump can be removed or installed simply by disconnecting the coupling, without the need to move the motor. 3. The rotation direction of the pump can be easily determined through the coupling, making it convenient to rotate the pump. Disadvantages: 1. It comes with a coupling, so it is necessary to align the motor shaft with the pump shaft. 2. The cost is high, as it includes additional components such as bearing suspensions, couplings, and coupling covers. 3. It requires a large amount of space, making it unsuitable for applications where space is limited. Generally speaking, when the power exceeds 30 KW, a non-direct connection should be used; for powers below 15 KW, a direct connection is sufficient. For powers between 15 and 30 KW, it depends on individual circumstances. These are general guidelines for making choices – there is no absolute best option; what matters most is suitability, with the specific decision depending on the actual operating conditions and the product requirements

I agree with you; what you said is spot on~~

There are now high-temperature permanent magnets that can be used up to 250°C, but they failed the tests due to manufacturing issues. Actually, it has nothing to do with magnets.