Which type of pump is typically started with its discharge valve closed?

The correct answer is that a centrifugal pump is typically started with its discharge valve closed to prevent damage and ensure proper operation. When a centrifugal pump starts, it relies on the fluid being present for proper operation, and closing the discharge allows the pump to build up pressure.

Starting with the discharge valve closed helps to avoid issues such as water hammer or mechanical damage due to running dry. Once the pump reaches an optimal operating condition and pressure, the discharge valve can be gradually opened.

In contrast, other types of pumps, such as positive displacement pumps, operate effectively even with the discharge valve fully closed, as they can generate pressure regardless of the system's conditions. This characteristic is crucial to understanding the fundamental differences in how various pumps function and the situations in which they are used efficiently.