The centrifugal pump is a hydraulic turbomachine capable of processing the fluid by the work done due to centrifugal effect through fixed and rotating channels always open, without modifying the compressibility of the fluid itself. Hence the name centrifugal pump. The mechanical movement imparted by the motor to the impeller provides kinetic energy to the flow (acceleration in the radial direction) which is transformed into pressure energy in the subsequent diverging channels. The main components of a vertical 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 use of the centrifugal pump and the processed fluid), it consists of a series of curved blades that form increasingly larger channels as the radius increases. The open impeller allows the passage of slightly dirty liquids, while the processing of fluids with viscosities up to 500 CPS or specific weights up to 1.9 kg/L is guaranteed by the solid and concentric movement of the impeller relative to the motor, connected via a shaft and a transmission coupling. It is possible to achieve different volumetric flows [m3/h] and heads [m] by controlling the diameter, curvature, height, and number of blades of the impeller. For each impeller, there will be a characteristic curve of the centrifugal pump, i.e., what head 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 axial vertical suction of the fluid and radial delivery to the side, conveyed upwards through a discharge pipe. In addition to directing the flow, it is also fundamental for the performance of the centrifugal pump: the increasing area appropriately slows down the fluid, thus the kinetic energy is transformed into pressure energy.
  • The wear bushing is the component that works by friction, thus subjected to greater wear. It keeps the shaft in a perfectly concentric position relative to the motor, which otherwise would rotate eccentrically due to the forces acting on the impeller. It consists of a rotating part integral with the impeller and a fixed part locked relative to the static components of the centrifugal pump. Normally a centrifugal pump reaches rotational speeds of about 3000 rpm, so it reaches very high temperatures in a very short time. It is essential that the bushing is always cooled (by the working liquid itself) and that the centrifugal pump is never operated dry, otherwise, there is a risk of melting the fixed components. The bushing is made of silicon carbide and Teflon, which guarantee less wear, greater mechanical and chemical resistance, and better withstand thermal shocks, allowing it to work at higher temperatures.
  • The lantern contains the motion transmission elements: shaft and bearing connected to the motor via the transmission coupling. It must ensure perfect concentricity between fixed and rotating parts. To it is connected the covering column, which will come into contact with the fluid, via a support plate. The overall structure must be as solid and stable as possible to minimize vibrations that would be transmitted along the entire length of the vertical centrifugal pump.
  • The motor is the part that transmits motion. In most cases, it is a 2-pole electric motor (about 3000 rpm). Depending on the number of revolutions, different characteristic curves of the centrifugal pump can be obtained.

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