Which type of pump can operate against a closed valve?

A centrifugal pump is designed to move fluid through the use of rotational energy, typically generated by a rotating impeller. This type of pump is most effective when it operates in conditions where it has a designated flow path. When faced with a closed valve, a centrifugal pump may not be able to efficiently build pressure and can suffer from cavitation or failure to operate, as it depends on the flow of the liquid to maintain its operation.

In contrast, a positive displacement pump continuously moves the same amount of fluid with each cycle regardless of the pressure conditions. This means that if a valve is closed, the pump can still build pressure against the closed system. Similarly, gear pumps and diaphragm pumps are also types of positive displacement pumps. They can handle situations where they need to operate against resistance, including closed valves, because they create pressure by trapping a fixed volume of fluid and moving it through the system.

The key to understanding why centrifugal pumps are not suitable for operation against a closed valve lies in their dependence on continuous flow to create the necessary pressure differential. When flow is restricted, as it would be with a closed valve, the centrifugal design cannot maintain its designated efficiency or function properly. Therefore, this makes the correct response refer to a positive displacement pump, as it