The centrifugal pump is a hydraulic operating turbomachine capable of processing the fluid through centrifugal effect in fixed and rotating channels always open, without altering the fluid's compressibility. Hence the name centrifugal pump. The rotation imparted by the magnets to the impeller provides kinetic energy to the flow (radial acceleration), which is converted into pressure energy in the subsequent diverging channels.
The main components of a magnetic drive centrifugal pump are:
The impeller is the main component of the centrifugal pump and the moving part with which the fluid exchanges energy. Made of plastic material reinforced with fibers (PP + FRP or PVDF + CF depending on the centrifugal pump's use and the processed fluid), it consists of a series of curved blades forming increasingly larger channels as the radius increases. The closed impeller increases the efficiency of the pump (less head loss) but does not allow the passage of dirty liquids. It is directly keyed to the internal magnet with which it rotates integrally and is supported by a fixed shaft. There is no direct connection between motor and impeller; the motion is transmitted only through magnetic interaction, hence the importance of using low viscosity fluids (max 200 cps).
Different volumetric flows [m³/h] and head [m] can be achieved by controlling the impeller's diameter, curvature, height, and number of blades.
For each impeller, there will be a characteristic curve of the magnetic drive centrifugal pump, i.e., the head that can be achieved given a certain flow rate, the operating range, and the working point.
The pump body or volute, snail-shaped, with an increasing section in the direction of motion, allows the fluid to be sucked in axially and discharged radially upwards. In addition to directing the flow, it is also fundamental for the performance of the magnetic drive centrifugal pump: the increasing area appropriately slows down the fluid, so the kinetic energy is transformed into pressure energy.
The external magnet is keyed to the motor and transmits its rotation to the impeller. It never comes into contact with the fluid, so it is not subject to wear and corrosion phenomena.
The separator cup ensures the isolation of the fluid and the hydraulic part from the external environment. It is completely sealed to prevent liquid leakage. It divides the impeller (and the internal magnet) from the external magnet and is made of the same material as the pump body to ensure chemical compatibility with the liquid but does not affect magnetic drive. In a magnetic drive pump, the impeller's concentricity is maintained by magnetic forces in the radial direction and by the fixed shaft relative to the cup.
The motor is the part that imparts rotation. In most common cases, it is a 2-pole electric motor (about 3000 rpm). Different characteristic curves of the magnetic drive centrifugal pump can be obtained based on the number of revolutions.