Magnetic Drive for Pump Applications

Disadvantages are the limits of torque you can apply to the impeller with a mag drive. Viscosity is an enemy of mag drive pumps.

They cost more.

I thought the ratio is 1:1. Unless it's slipping.

Why not use a SS pump. Goulds,(Not an endorsement) and others make them.

Or, plastic. Serfilco(Not an endorsement)and others make them.

Hi Lynlynch.

I've been puzzling on your second sentence all evening, whilst wearing my taxi-drivers' hat and ferrying the kids here there and everywhere. Surely the constraints on a mag-drive centrif on viscous liquids are the constraints relating to the centrif pump, not the mag-drive? There are mag-drive screw pumps and gear pumps that will handle more than 16,000 centistokes, and I've seen a small mag-drive gear pump pumping a gell of about 50,000cst. Surely a mag-drive centrif will handle as much viscosity as a mechanically sealed centrif?

OK. You're right.

I thought WEG made motors, not pumps. Are you sure it's a WEG pump?

Correction: a magnet drive pump does have bearings (bushes) in the fluid, a mechanically sealed pump does not (I assume we're talking centrifs here). Corrosion is no less an issue with mag-drives than with mechanically sealed pumps, and is not a reason to select one.

Mag-drives should be used on applications where leakage should be avoided at all costs, ie toxic and dangerous fluids, or on liquids that are very difficult/complex/expensive to seal.

Disadvantages: Cost. Not recommended for abrasive fluids. Can unwittingly be used in applications where it shouldn't be, although this happens much less frequently than in the early days. It can be difficult/dangerous to assemble/disassemble a very powerful one (eg 75kw).

I'm not sure why a mag-drive should be used on high salinity water, unless it's one that happened to be lying around. What are the pump materials.

you are right it is a FTI pump model UC326. Are there any articles on mag drives?? or general references on them?

"Guest",

WEG is a motor vendor, not a pump manufacturer...try to look a little closer at the casing....scrape the dirt away.

Why can't you get more information about this pump..? Did the new plant staff throw away all documentation, like they always do when the plant is sold ? Does anybody care ?

Other Disadvantages:

- Cant tell the direction of rotation, without a special device

- Temperature monitoring of the bearing may be an advantage

- Possible problems on start-up with silicon carbide bearings.

I agree with the comments about the pump service. It doesn't seem that salt water requires a mag-drive pump....

Unless of course, Banu, there is something you haven't told us ?

Regards.

Photo Film processors use Magnetic drives.

I had been working on Kodak's X-Ray Films Processor in which it was used.

Where leakage of active chemicals is important, cost or efficiency is of 2nd priority.

If you look into maintenance cost in view you will appreciate its use.

As posted mag drive pumps do have bearings at the pump end and also have very close clearances between the driven magnets and the can that contains the fluid being pumped. The bearings are lubed and cooled by the fluid being pumped. Heat is a big enemy and most have heat sensors to shut down before catastrophic failure.

A bigger problem in many applications is dirt and crystals. Most bearings used will withstand some abuse but the usually SS can is thin and fragile - the driving and driven magnets need to be close together but separated by the can - atmosphere on one side and fluid on the other.

My advice - if you don't absolutely have to have one don't buy one. One mag drive pump failure will cost more than many years of seal maintenance.