What is a characteristic of centrifugal pumps?

Centrifugal pumps are designed to convert rotational kinetic energy, typically from a motor, into the energy of fluid flow. One of the fundamental characteristics of centrifugal pumps is the relationship between discharge flow and discharge head. As the discharge head increases, the flow rate of the liquid being pumped tends to decrease. This behavior is due to the pump’s ability to generate pressure through centrifugal force, but as the pressure in the system rises (i.e., as discharge head increases), it becomes more challenging for the pump to maintain the same flow rate.

In practical terms, this means that as you raise the head against which a centrifugal pump must work (for example, if you were pumping to a higher elevation or through increased resistance in piping), the flow rate will drop off. Understanding this characteristic helps engineers design systems appropriately, ensuring that the pump selected is capable of meeting the required flow and pressure specifications under expected operational conditions.

In contrast, other types of pumps, such as positive displacement pumps, work differently, as their flow rate is typically constant regardless of the pressure conditions. Therefore, the behavior of centrifugal pumps under varying discharge head conditions is a crucial element in understanding their operation and the systems they are used within.