How do magnetic drive pumps work?
Take a look at magnetic coupling and why the mag drive is so popular
The key part of a magnetic drive pump that sets it apart from other pumps is the magnetic coupling.
Magnetic coupling is an innovative method for transferring torque from one shaft to another without a direct mechanical connection. By utilising magnetic fields to transmit motion and force, magnetic couplings provide a reliable, maintenance-friendly, and leak-free solution for various applications. Here's an in-depth look at how magnetic coupling works and its key features.
Magnetic coupling is an innovative method for transferring torque from one shaft to another without a direct mechanical connection. By utilising magnetic fields to transmit motion and force, magnetic couplings provide a reliable, maintenance-friendly, and leak-free solution for various applications. Here's an in-depth look at how magnetic coupling works and its key features.
How magnetic coupling works
- Drive Magnet (Outer Magnet Assembly): Connected to the motor, this component rotates with the motor shaft, without any contact with the fluid being pumped
- Driven Magnet (Inner Magnet Assembly): Attached to the impeller or the driven component inside the pump housing, is in contact with the fluid being pumped – it is commonly referred to as the wet end.
Reference: Image taken from Iwaki’s magnetic drive pump principle video
Rear Casing
A non-magnetic barrier separates the inner and outer magnet assemblies. This shell contains the pumped fluid, preventing leaks and ensuring the magnetic fields can interact without physical contact.
Torque Transfer
- When the motor shaft rotates, it turns the outer magnet assembly.
- The magnetic field generated by the outer magnets exerts a force on the inner magnets, causing them to rotate synchronously.
- This rotation drives the impeller, moving the fluid through the pump.
Reference: Image taken from Iwaki’s magnetic drive pump principle video
Key features of magnetic coupling
Leak-free operation
Magnetic couplings eliminate the need for mechanical seals between the pump shaft, the pump rear casing and the impeller. Without seals to wear out and leak, these couplings are ideal for handling hazardous, corrosive, or valuable fluids.
Reduced maintenance
The absence of mechanical seals and direct contact components means fewer parts are subject to wear and tear. This results in lower maintenance requirements and a longer service life for the pump. In addition, assembly is quick and simple with no mechanical seal compression settings to worry about.
Enhanced safety
The containment shell ensures that the fluid remains completely isolated from the external environment. This minimises the risk of leaks and spills, which is crucial when handling toxic or flammable substances.
Pro’s & cons of magnetic drive pumps
Magnetic drive pumps offer excellent benefits for certain fluid transfer applications, but they are not suitable for all. Their specific limitations can make them less ideal for some scenarios.
Pro's
- Very low risk of fluid emissions from the pump.
- Low maintenance seal less design.
- No mechanical seal materials selection choices.
- No expensive mechanical seal support systems.
- No pump to motor alignment problems.
- Magnetic coupling means no damages to the motor if pump gets jammed.
- Quick wet end and service replacement.
- Positive attribute in an organisation’s safety, health and environment activities.
Con's
- Very limited solids handling.
- Magnetic drive pumps are known to struggle with low flow and dry running, manufacturers are making protection devices available to support engineers where this is a potential issue.
- Limited in torque transmission capacity due to strength of magnets.
- Typically require higher motor power than mechanically sealed pumps for the same duty.
- Minimum Flow requirements: a) stable minimum flow rate to ensure the pump operates reliably, and b) thermal minimum flow rate to ensure heat generated in driven magnet/bearing section is dissipated.
Choosing the right magnetic drive pump for your application
Incorrect pump selection can cause more problems than it solves and can be costly for a plant. It’s crucial to leverage the technical expertise of pump manufacturers and their appointed sales distributors, they should seek to understand your application and requirements so they can recommend the correct pump and model.
Magnetic drive pump quality and cost
There are many different brands of magnetic drive pumps available on the market, each with their own qualities and price points. The cost and quality of magnetic drive pumps are directly connected to their reliability. In some applications, reliability is critical and justifies the investment in a higher-end pump. Other applications may not require such high levels of reliability.
Why high-end magnetic drive pumps cost more
High-end magnetic drive pumps are more costly due to several factors:
- The use of higher quality materials for pump component parts.
- Premium grade high strength magnets.
- Configuration to suit specialist applications.
- Significant investment in design and engineering.
- Rigorous quality control processes that add additional resources and costs.
When to invest in high-end magnetic drive pumps
Consider investing in higher-end magnetic drive pumps in applications where:
- Operational downtimes would have a high financial or reputational impact.
- High-value materials or those with severe health and safety implications are being handled.
- Ethics and sustainability are paramount. Higher-end pumps are often more energy-efficient and align better with stricter company ethical policies.
What applications are mag drive pumps used in?
Magnetic drive pumps, or mag drive pumps, are most suitable for applications where leak-free operation and handling of hazardous or corrosive fluids are critical. Here are some specific situations and industries where mag drive pumps excel:
1. Chemical Processing:
1. Chemical Processing:
- Handling aggressive and corrosive chemicals without the risk of leakage.
- Safe transfer of acids, bases, and solvents.
- Maintaining high purity levels by preventing contamination.
- Handling sensitive and sterile fluids.
- Ensuring hygiene and preventing contamination in the transfer of food-grade liquids.
- Suitable for CIP (clean-in-place) systems.
- Pumping chemicals for water treatment without leaks.
- Handling chlorinated and fluorinated solutions.
- Transporting hydrocarbons and other hazardous materials safely.
- Suitable for high-temperature applications.
- Pumping ultra-pure chemicals required for semiconductor production.
- Ensuring contamination-free processing.
- Precise and safe handling of various chemicals.
- Ideal for experimental setups requiring leak-proof operations.
- Suitable for any application requiring reliable, leak-free fluid transfer.
- Commonly used in cooling systems, circulation of heat transfer fluids, and more.
