If you’ve been exploring mag drive pumps, you’re likely already aware of the many benefits they offer—especially in demanding environments. But, like any technology, there are details worth considering before making a choice. In a recent series of Lunch and Learn sessions, we tackled some of the most common (and not-so-common) questions about mag drive pumps. We thought it’d be helpful to bring you answers straight from Denzil Harrison, Project Sales Consultant at Global Pumps, who’s worked with countless customers to find the right pump for their operations.
About this photo: During our Lunch & Learn at Agilitus, we had a great discussion on the benefits of mag drive pumps in handling aggressive chemicals.
Denzil: Thank you very much for having me, I hope these insights can help someone that’s designing or maintaining systems utilising these pumps.
1. Interviewer: So, what are the potential challenges with mag drive pumps?
Denzil: This is a great question, because mag drives are commonly known for their upsides, including safety while handling hazardous fluids, leak-free, and maintenance-free operation. One challenge to consider is dry running. This is no surprise, as few centrifugal pumps can handle dry running. For a mag drive pump, dry running can be catastrophic within 10-20 seconds. Without fluid to cool and lubricate the components, it can cause significant damage. Thankfully, mitigating this risk is quite simple with dry-run protection features, which automatically shut the pump off when fluid is absent.
Another challenge is that the magnetic coupling can be sensitive to extreme temperatures, which can lead to performance issues.
2. Thank you, that’s a good answer. Now, is there any slippage between the drive and impeller magnets?
Denzil: We get this question a lot, and in short, if you operate the pump within the normal operating parameters, there should be no slippage. It's only when you run the pump outside its recommended operating conditions—whether that's the pump curve, temperature limits, viscosity, or specific gravity (SG) of the fluid—that you might start to see slippage. This poses no major issue; the magnets will simply decouple, and in most cases, the system will detect a change in power draw and automatically turn the motor off to prevent damage. Once the drive magnet slows down enough, the impeller magnet will reconnect, and the pump will continue operating as normal.
3. That’s very interesting. And are there any eddy currents generated?
Denzil: It’s important to understand what eddy currents are—this is a form of energy loss that generates heat when a metallic object interferes with the magnetic field between two moving magnets. Eddy currents can be generated in certain mag drive pumps, depending mainly on the materials used for the containment shell.
In our standard Techniflo TB range, this containment shell is made of plastic and Kevlar, so NO eddy currents are generated.
If you move to more exotic materials to handle different and unique fluids, for example nitric acid, this may change. Using materials with low electrical conductivity in the pump’s construction can help reduce the generation of eddy currents.
4. Excellent. And last question, how do mag drive pumps perform with solids?
Denzil: Mag drive pumps should be considered as a pump for handling only clean fluids, but—and I’m stressing this “but”—they do have the added capability of handling solids. Some mag drives can handle up to 30-40% solids by weight, but it’s important to note that this will cause wear over time. The more solids, abrasiveness, and hardness you have, the more quickly the pump will wear down. In some cases, special coatings or alternative materials can be used to help reduce the wear and improve the pump's resistance to abrasion, extending its service life.
Mag drive pumps offer a number of benefits, including leak-free operation and the ability to handle hazardous fluids with safety and efficiency. However, as with any technology, there are certain considerations to keep in mind when selecting the right pump for your needs.
If you have any further questions or need expert advice, don’t hesitate to reach out to Denzil or any of our team at Global Pumps—we’re always here to help!
