What describes a rising characteristic curve in pump design?

A rising characteristic curve in pump design indicates that the head (or pressure output) of the pump increases as the flow capacity decreases. This behavior is characteristic of certain pump types, especially those that are designed to maintain pressure under varying flow conditions, such as positive displacement pumps.

In practical terms, when the flow rate decreases (for instance, when a valve restricts flow), the system may require the pump to provide more head pressure to overcome system resistance or to maintain adequate flow. Therefore, the rising characteristic curve ensures that as demand for fluid flow decreases, the pump compensates by increasing its head. This is particularly valuable in applications where maintaining pressure is critical, such as in water distribution systems or in certain industrial processes.

The other choices do not adequately describe a rising characteristic curve. A scenario where head decreases as capacity increases implies a different type of performance curve that is not reflective of a rising characteristic. Similarly, a constant head across all capacities would point to a flat characteristic curve, while regarding head as undesirable for parallel configurations misrepresents the interplay between pump performance and system design. Understanding rising characteristic curves is crucial for selecting the right pump for specific applications, ensuring efficiency and effectiveness in fluid transport systems.