In the last few years the magnetically coupled pump has increasingly been
recognized as a sophisticated design to solve critical pumping problems.
Inasmuch as no shaft penetrates into the body of the pump, there is no need
for a shaft seal with its constant drag. Torque is transmitted by a magnetic
field from the magnet attached to the motor through the solid body to the
magnet attached to
impeller. No shaft, no seals, no seal leaks, no air leaks and no friction.
It is important to remember that a magnetic drive pump behaves like any
other centrifugal pump, and all the laws of centrifugal pump design still
apply. An exception is when liquids with a specific gravity over 1.2 are
to be pumped, then the magnetic drive takes on added importance.
Since the magnetic torque governs the output, anyone misapplying the pump,
especially with liquids heavier than water, will find a built-in safety
factor that will protect the users investment: the slipping of the
magnets avoids motor burnout. If a typical seal-type pump is misapplied,
can overload the motor and cause a burnout.
In contrast the magnetic drive will indicate a problem and save the entire
pump. If the impeller diameter is reduced as necessary to fit the specific
solution as recommended by the factory, the magnetic drive offers reliable,
trouble-free performance for many years. Since there are only two moving
areas in the pump, the motor and the impeller assembly, there is very little
to go wrong. Should abrasive solutions be pumped, depending on percentages
of solids, bushing materials with different degrees of resistance are available.