Magnetic pump - a seal-less centrifugal pump

Sealless magnetic drive pump, when and where can you use it?

There are various arguments why you want to use a seal-less pump in your process. Main advantages of a seal-less magnetic drive pump are:

• Minimising the risk of leakage, which in turn improves safety for staff and the environment. This is especially important when pumping hazardous liquids, such as corrosive acids.
• No mechanical shaft seal, which means less maintenance
• Easy installation

At the right operating point and continuous operation, the pumps have a long service life.

How does the sealless magnetic drive pump work?

Unlike conventional shaft-sealed centrifugal pumps, there is no physical coupling between the motor and the pump, but the power is transmitted by magnetism. Magnets are mounted inside the impeller and these are synchronously coupled to magnets in an enclosing casing that is connected to the motor. The fluid we pump is also used for cooling and lubrication, thus ensuring that the pump does not overheat during operation.

Which liquids are suitable for sealless magnetic drive pumps?

• Pure liquids, neither fibres nor particles
• Non-viscous liquids

There is a risk that particles and fibres will clog channels that are needed for the pump to work. When these are clogged, the liquid no longer carries the bearing and contact occurs between the pump parts. This in turn causes a lot of heat generation and there is a high risk of dry running and we will damage the pump.

Can you dry run a magnetic drive pump?

Most magnetic drive centrifugal pumps suffer from dry running. If the liquid starts to boil or cavitation occurs, you get air bubbles inside the pump. The air bubbles prevent the bearings in the seal-less pump from being cooled and there is a high risk of permanent damage to the pump.
The self-priming magnetic drive pumps can run dry, but you cannot start without liquid. This means that you can empty a container completely as liquid is not evacuated from the pump housing. In this case, we should bear in mind that the liquid may boil away after a while and possibly dry running may still occur.

Metal or linear magnetic drive pumps?

The choice of material depends on the fluid you are going to pump. There is therefore no simple rule when choosing a particular pump type. Each media has its own challenges and we therefore need to use different resistance tables to find the right material choice.
For example, you can pump hydrofluoric acid, HF, with a metal pump if the temperature is low, but at higher temperatures it is better to pump the acid with a lined pump. Metal pumps generally have a higher efficiency than a lined pump, as the expansion coefficient for plastics is greater than for metal. However, metal alloy pumps are relatively expensive.

What volumes and pressure heads can a sealless magnetic drive pump handle?

Lyma range of sealless pumps is large and we have everything from linear self-priming to large transport pumps with capacities of up to 400 m3 / h and lifting heights up to 90 metres. For magnetically driven metal pumps, we can offer pumps with flow rates up to up to 1300 m3 / h and a lifting height of up to 135 metres. However, if you need higher pressure, you may need to use a canned motor pump. The canned motor pump can handle several hundred bar and at the same time very hot liquids.

If you have a lot of particles in the medium, you should consider other options. For example, you can use a hose- or membrane pump.

Contact us for more information

We have good experience in sealless pumps in the process industry. We have supplied many of these pumps over the years and you can rest assured that we will deliver a reliable solution to your needs.