What effect does an increase in the impeller diameter have in a centrifugal pump?

In a centrifugal pump, increasing the impeller diameter has a significant impact on the flow characteristics of the pump. Specifically, as the impeller diameter increases, the quantity of fluid pumped, or flow rate, tends to increase as well. This is because a larger impeller can move a greater volume of fluid with each rotation due to its increased surface area and effective centrifugal action.

The relationship between impeller diameter and flow rate is generally considered to vary directly; that is, for a given speed of the pump, a larger impeller will allow for a higher flow rate. This characteristic is crucial for power engineers to understand, as it influences system design and efficiency in fluid transport.

While the head produced by a centrifugal pump also changes with the impeller diameter, the direct relationship primarily emphasizes the effect on quantity rather than a straightforward increase in head. Hence, the correct answer reflects the direct relationship between impeller diameter and the volume of fluid moved by the pump.