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Magnetic Drive Pumps

Operating Principle:

A magnetic drive pump operates identical to any centrifugal pump except that the need for a shaft seal is eliminated. This is accomplished by driving the impeller with a magnetic coupling rather than directly with the motor shaft. Motor torque is transmitted by the magnetic field created by two magnets, one attached to the motor shaft and the other encapsulated in the impeller. This magnetic field is transmitted through a plastic housing that separates the drive magnet and the driven impeller from the fluid being pumped. Full motor torque is directly transferred to the impeller with less power consumption due to the elimination of the friction that a shaft seal would create. The other problems associated with seals, such as leakage and maintenance due to wear are also eliminated. The magnetic coupling also provides a safety factor to protect both the pump and the motor if the pump is misapplied. If the pump load becomes larger than the available coupling torque, the magnets will decouple. This decoupling could save the motor from burnout due to excessive loads and prevent possible damage to the pump head.

It should be noted that magnetic drive pumps must be used where a flooded suction condition exists. Dry run operation is possible on certain models with particular combinations of materials of construction, but is not recommended.

Can these pumps be run dry?

GRI does not recommend running any of the magnetic drive pumps in a dry run condition although certain models with certain materials of construction can be run dry for short periods of time without damage. GRI should be contacted for the particular model in question.

What does decoupling mean?

Decoupling occurs when the driven magnet in the impeller becomes desynchronized from the drive magnet and stops turning. The pump will stop pumping but the motor will continue to run at its no-load speed.

What causes decoupling?

An increased pump load that exceeds the torque capability of the magnetic coupling would most likely cause decoupling.

Can the magnetic coupling be restored?

The magnet coupling can be restored by bringing the motor to a complete stop and then restarting. The excess load causing the decoupling should be identified and eliminated to prevent reoccurrence.

Is my pump compatible with the fluid or chemical solution that I am pumping?

Care needs to be taken when matching a pump to a certain chemical solution. Most materials of construction for wetted parts are compatible for typical chemicals encountered and will meet or exceed potential application demands. Consult GRI to verify a particular application.

How do you recommend connecting my system piping to your pump?

It is recommended that pumps not be hard connected directly to rigid piping. It is best that flexible tubing be used when connecting to the suction and discharge ports. Where pipe threads are provided, it is recommended that all fittings be hand tightened to prevent body cracking due to over-tightening.

How will my pump compare to published pump curves?

All GRI performance testing is done using water at room temperature as the pumped fluid. Specifications will vary for a particular application depending on the properties of the specific fluid, temperatures and other operating conditions.

What if I don't see a model from the catalog information that matches my requirements?

Contact GRI to see if one of our standard pumps can be modified or adapted to your application. If not, our area of expertise is in the design and development of new pumps to meet special customer requirements.

Magnetic Drive Pumps Overview (PDF 224K)

15651 Series (PDF 316K)

16650 Series (PDF 108K)

17650 Series (PDF 136K)

18650 Series (PDF 140K)

14110, 14518 & 14520 Series (PDF 192K)

Service Data Sheet 14110 (240K)

Service Data Sheet 14518 (202K)

Service Data Sheet 14520 (193K)

15700 Series (PDF 188K)

Service Data Sheet (201K)

Replacement Kits (PDF 136K)

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