What defines a drooping characteristic curve in pumps?

A drooping characteristic curve in pumps is defined primarily by the behavior of the pump as the flow rate changes. In this context, the correct choice indicates that the head developed at shutoff is low compared to other capacities. This characteristic is significant as it highlights the pump's performance at low flow rates, demonstrating a relatively lower head output when the pump is operated close to its shutoff point.

Such a performance curve indicates that as flow rate decreases, the head does not significantly increase, which is characteristic of a drooping curve. This behavior can affect system performance, particularly when assessing how the pump will operate in actual service conditions.

Understanding this curve is crucial for designing plumbing systems, particularly when considering how pumps will perform under varying load conditions, as a low shutoff head can impact the ability to adequately service demand at lower flow rates.