How to choose between a magnetic pump and a shielded pump

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Magnetic pumps or shielded pumps are being used more and more often for transporting flammable, explosive, toxic, harmful, and highly corrosive materials. So what is the difference between magnetic drive pumps and canned motor pumps? In what situations is it better to use a magnetic pump, and in what situations is it better to use a canned motor pump? Today, we will discuss in detail the differences between magnetic pumps and shielded pumps from an application perspective. 1. Shielded pumps utilize the principle of electric motors directly, whereas in magnetic drive pumps, the energy consumed by the motor has to be transmitted to the impeller through the internal and external magnets (with some of this energy being converted into heat in the magnets); therefore, shielded pumps are theoretically more efficient than magnetic drive pumps. 2. The disadvantage of shielded pumps is that they cannot be repaired (it is very difficult); whether there are problems with the pump body or the motor during use, users are basically unable to carry out repairs on their own. Repairing magnetic pump is not much different from repairing ordinary pumps. Since the motor bearings of shielded pumps come into contact with the medium, it is difficult to ensure their service life. Therefore, canned pumps are difficult to maintain on a daily basis and hard to repair, and their reliability cannot be guaranteed (for instance, bearing failures cannot be predicted, and it is not possible to detect or observe any signs of trouble). Canned pumps are unable to identify potential problems during operation, and once issues arise, they can cause catastrophic damage. 3. The thickness of the isolation sleeve in magnetic pump is more than 3 times that of a shielded pump, thus ensuring better sealing performance and reliability. 4. The motor bearings of the shielded pump are lubricated by the medium; the motor does not have a fan, and its heat dissipation is achieved through the internal circulation of the medium to carry away heat. This results in a higher failure rate for such shielded motors. The motor of the magnetic pump is a regular motor that relies on a fan for cooling, offering stability and reliability. But this also means that the noise level of this magnetic pump is higher than that of a shielded pump. 5. The structure of the shielded pump is more compact, allowing it to be smaller in size than magnetic pumps and thus saving space. 6. Shielded pumps have no couplings, while magnetic pumps are connected to the motor via a coupling, which requires alignment. 7. Due to the issues related to magnetic materials, magnetic pump systems can achieve a lower maximum power output compared to shielded pumps; this limits their use in applications that require high flow rates and high pressures and thus involve heavy loads. 8. Magnetic pumps are more suitable for highly corrosive media than shielded pumps, as their isolation sleeves are thicker (thickening the isolation sleeve of a shielded pump affects the electromagnetic interaction between the stator windings and the rotor windings). 9. Magnetic pumps cannot be used in situations where the medium contains metal particles (such as iron shavings), because ferromagnetic materials will be attracted to the magnets, causing failures. And shielded pumps can handle it. Therefore, when choosing the type of pump, if low purchase cost (initial investment cost) is the only consideration, use a canned motor pump. Considering future operation and maintenance costs, it is recommended to use a magnetic pump. Additionally, if the corrosiveness is particularly high, it is recommended to use a magnetic pump as well. If it contains particles (especially metallic ferromagnetic particles), a shielded pump should still be used. If high process reliability is required and the medium is highly dangerous with no leakage allowed, magnetic pumps are safer.