The main parts of the centrifugal pump include motor, coupling, shaft, shaft seal, cavity, impeller, volute, diffuser, inlet flange, outlet flange, pump housing, impeller seal, etc. Relatively speaking, centrifugal pump with larger cavity and more impeller channels have higher working efficiency when compared to other types of centrifugal pump even though they share the similar main parts.
Of course it is important to understand the basic components of the centrifugal pump yet there is more to be known if we want to design better centrifugal pump models that fit with the working conditions very well and one of the major issues is the design of the impeller since the lifetime of the centrifugal pump depends on the mechanical shaft seals, the pumping liquid, and pressure. As a matter of fact, a compromise has to be found and made between the possible friction loss and the uniform velocity profiles even though the latter can be achieved by the extension of centrifugal pump impeller blades without any impact on the efficiency of the pump as a whole. What is more, since centrifugal pump is usually driven by an electric motor, the coupling parts between the motor and the shaft seal needs to be maintained on a regular basis since that position needs to seal a shaft that is constantly rotating and moving up and down.
And it should be pointed out that in terms of the coupling connection types there are some differences between varied centrifugal pumps. For instance, runner centrifugal pump has highly flexible coupling connection while that of rotor centrifugal pump is relatively static and the advantage of the former type lies in its use of standardized motors. Yet the disadvantage of the former is also clear since the motor and the pumping fluids are separated from each other by a shaft seal while in the case of the latter, the sealing between the motor may be restricted by separation of a long shaft or seal rings.
Due to these reasons, centrifugal pump with mechanical shaft seals is highly recommended by experts since it is not only maintenance free but also has a smaller leakage rate even when it is filled with compressed pumping materials. On the other hand, if the motor and the centrifugal pump fluid are separated, the two parts may not contact with each other even when the shaft seal is left out, which can be only solved by such mounting options as placing the motor in higher position then the centrifugal pump surface in the system. Once the compromise has been made, the centrifugal pump efficiency will be improved and the leak problem will be mitigated or even eliminated once and for all thanks to the clearance between the friction of the shaft and the pump housing.