A pump that is driven by an electric motor using two sets of permanent magnets (see image). The outer magnet set is driven by an electric motor. As the outer magnet set rotates within the rear housing, the impeller, which is attached to the inner drive magnet set, spins at the same rotational speed as the outer magnet set. It is the attraction of the inner and outer drive magnets that allows a torque to be transmitted to the pump impeller. Since the motor shaft does not extend into the interior of the pump, there is no need for a shaft seal.
Two major disadvantages of magnetic drive pumps are 1) they are not suitable for pumping applications containing suspended solids; and 2) they cannot be run dry for extended periods of time. A dry running condition will lead to rapid overheating and severe damage to internal bearing surfaces.