Canned Motor Pumps
Canned Motor Pumps
The chemical industry’s recognition of the advantages of these pumps followed soon thereafter. Indeed, the additional demand created a widespread economic base for the manufacture of canned motor pumps.
Canned motor pumps had evolved to the point of standardization. Expanding populations and rising standards of living in both the industrial and developing countries required innovative technologies to solve the demanding and progressively urgent problems of protecting the environment. Increasingly, canned motor pumps became part of the answer.
In some instances, the cost of seal support and monitoring systems is disproportionate to the potential success. It is only fair to point out the existence of services that simply cannot be performed using “open” or conventionally sealed centrifugal pumps. Absolutely hermetic transport of fluids using centrifugal pumps is only possible where the torque applied to the pump rotor is generated externally. To satisfy this requirement, a rigid external stator system using either electromagnets or permanent magnets is needed. In some industries, conventionally sealed pumps can endanger human life and physical assets. Thus, traditionally sealed pumps are not always “best available technology.” Accordingly, wherever the state-of-the-art makes this protection feasible, the means employed must be aligned with the results achieved.
And so, keeping in mind the limitations of “open design” pumps (those with packing or mechanical shaft seals) that can contribute to air and water pollution, we should endeavor to be thoroughly acquainted with state-of-the-art of hermetic drive techniques for centrifugal pumps. The facts may surprise us.
Design and functional description As extremely environmentally sound machines, canned motor “hermetic” pumps are now very widely used in Europe and Japan. While making inroads in the United States, lost ground needs to be recovered in our quest for competitiveness. That said, wherever it is necessary to move dangerous, toxic, polluting, expensive, caustic, potentially explosive, high-temperature or low-temperature fluids, canned motor pumps deserve very close consideration.