When a magnetic drive centrifugal pump is a no-brainer
Centrifugal pumps are usually either sealed or seal-less. Centrifugal pumps with magnetic drive are an important type of seal-less pumps commonly found in chemical plants because they can be stripped and rebuilt in the field. Another advantage is that they don’t usually require traditional alignment.
So how are these pumps different to traditional pumps?
With magnetic drive (mag-drive) centrifugal pumps, the electric motor (driver) is coupled to the pump magnetically rather than via an electric motor shaft. The pump has a drive magnet that eliminates the need for shaft sealing. This gives it a major advantage over traditional pumps because there is no risk of leakage (except in a rare situation when the pump casing breaks).
Magnetic drive pumps (also known as mag-drive pumps) are most often used in applications that are hard to seal and/or where leakage is a threat to people or the environment. Many facilities prefer these pumps to eliminate issues with seals (and potential downtime for repairs), or when they pump fluid that is just too expensive to waste.
The seal-less advantage
Seals themselves are a major cause of pump trips and unscheduled shutdowns, so seal-less pumps actually improve the performance, reliability and availability of a facility’s system. Without seals, there is no friction loss, wear, or noise, all of which affect traditional pumps. Of course, mag-drive pumps have disadvantages too (read the pros and cons of these pumps to find out more).
Magnetic coupling for the win
Another area where this pump excels is due to the magnetic coupling. This allows reduced shocks and torque spikes, acting as a fuse in extreme conditions. The magnetic couplings can temporarily break if pump has too great a load to prevent damage to the pump.
These pumps are usually used where leakage of the pumped fluid can be risky for workers or the environment. Sealed pumps can leak over time and one has to install complex double seals to prevent liquids escaping into the atmosphere – causing safety issues, increased maintenance and costly downtime.
Liquids like acids, pollutants and toxic fluids as well as exotic materials or corrosives are usually pumped with these pumps for this reason. Mag-drive pumps are also commonly used for high-purity liquids (where leakage would be very costly) and liquids that are hard to seal. With these pumps, there is significant improvements to operator safety and the facility can meet safety regulations more easily.
Another application for these pumps is difficult liquids that can crystallize on seal faces, causing the seal to fail. Engineers use a permanent flush system to avoid this, but the cost of the seal-flush liquid, maintenance and energy consumption increases running costs. By using these pumps, a facility can lower their costs overall.
Choosing the right material
Seal-less pumps are a no-brainer for most applications, but choosing the correct material and metallurgies is not. While these pumps come in metallic and non-metallic materials and most metallurgies, the choice of metallic or non-metallic materials can depend on the temperature and corrosiveness of the liquid – as well as on your budget.
Non-metallic options are often lined with polymer to improve corrosion resistance. Metallic pumps can be used for higher temperatures (read more about the importance of temperature and torque on Magnetic-drive pumps). The higher costs of these pumps, however, even when taking into account add-ons like corrosion resistant casing and metallic options, are offset by the life of the pump.
Need advice on magnetic-drive centrifugal pumps? We are your industrial pump supplier in Canada. Give us a call on 1-800-367-4180 (toll-free). Our experts are on hand to help you choose, install, maintain, and monitor a variety of equipment. And to answer questions about things you’ve previously tried gone wrong.