Magnetic Drive Pumps
Pumps whose impeller is not connected directly to the motor. Instead, the motor and impeller are each connected to magnets. As the motor spins its magnet, the other magnet spins which cause the impeller to turn. Small centrifugal pumps (e.g. for garden fountains) may be magnetically coupled to avoid leakage of water into the motor.
The motor drives a rotor carrying a pair of permanent magnets and these drag round a second pair of permanent magnets attached to the pump impeller. There is no direct connection between the motor shaft and the impeller so no gland is needed and, unless the casing is broken, there is no risk of leakage. Magnetic drives can also be applied to gear pumps in the same way.