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Canned Motor Pumps

What is a canned motor pump?

A type of pump designed to move fluids with absolutely no chance of leakage. They are considered an alternative to a magnetic drive pump that insures zero leakage, while at the same time eliminating the mechanical seal, which is often the most expensive component to maintain in a pump. This makes canned motor pumps ideal for pumping dangerous or difficult fluids such as radioactive coolant, very expensive heat transfer liquids that are prone to evaporation when pumped with conventionally mechanically sealed pumps, and extremely corrosive or noxious liquids. They are most commonly centrifugal pumps, but their design can also be incorporated into rotary positive displacement pumps.

How do they work?

The pumping mechanism consists of a motor that is close-coupled to the pump, with both components being contained in a hermetically sealed chamber that allows no leakage. The rotor of the motor is exposed to the liquid being pumped, as there is a circulation path of a portion of the pumped liquid through the motor rotor, to lubricate the sleeve bearings and thrust surfaces that are part of the pump and motor. This circulating liquid then returns to the pump end, where it is ultimately pumped out of the discharge of the pump. The stator of the motor is isolated from the liquid that is circulating through the rotor by a metallic can so that the motor stator remains dry. Since the sleeve bearings and thrust washers in the motor rotor must be lubricated by the circulating liquid, these bearings are made of hardened wear resistant materials such as silicon carbide or tungsten carbide.

Where are they used?

Canned motor pumps are used exclusively for toxic, noxious, or aggressive fluids. They may be used for water, but there would be no reason to do so. The leak-proof feature makes them ideal for use in the nuclear power industry, in the chemical industry, and in any other area where the fluid can't come into contact with the environment.

Here are some canned motor pump manufacturers to consider.

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