Centrifugal pumps can be divided into several types except which of the following?

Centrifugal pumps are primarily categorized based on their design and the mechanism by which they move fluid, and this classification generally includes volute, regenerative, and axial flow types. Each of these types operates on the principle of converting rotational kinetic energy from the impeller into hydrodynamic energy in the fluid.

Volute pumps utilize a spiral casing to gradually expand the flow area, which helps convert high velocity into pressure. Regenerative pumps, on the other hand, use an impeller that has progressively increasing diameter to generate high head at lower flow rates, making them efficient for certain specific applications. Axial flow pumps move fluid parallel to the impeller shaft, which is suitable for high flow and low head applications.

In contrast, gear pumps are a different category of pump entirely. They do not operate on the centrifugal principle but instead rely on the meshing of gears to move fluid. This makes them positive displacement pumps rather than centrifugal pumps. Thus, gear pumps do not fit into the classification of centrifugal pump types. This distinction explains why the correct answer is the choice that identifies gear pumps as a type not associated with centrifugal pumps.