Which type of pumps cannot pump against a closed valve?

Displacement pumps, including reciprocating pumps, rely on the direct movement of fluid to create pressure. When faced with a closed valve, these pumps cannot continue to build pressure to overcome the resistance presented by that closed valve, as they depend on a consistent flow path to function effectively. This characteristic makes them unsuitable for pumping against a closed system because they need to move fluid in a way that allows for displacement.

Reciprocating pumps specifically utilize pistons or diaphragms to push the fluid, and if there’s no outlet (due to a closed valve), they will quickly reach a point where they cannot impart any momentum to the fluid, leading to potential stalling or significant strain on the pump components.

In contrast, other pump types mentioned, such as centrifugal pumps, can handle some degree of closed or obstructed flow, but ultimately, they too have limitations based on their design and are not the correct match for this specific scenario. The design and operational mechanics of displacement pumps are fundamentally what leads them to be unable to effectively operate against a closed valve.