Why must centrifugal pumps be located close to or below the liquid surface?

Centrifugal pumps need to be located close to or below the liquid surface primarily because they operate based on the principle of creating a pressure difference to draw fluid into the pump. When positioned near or below the liquid level, the pump can achieve positive suction head, which is essential for effective operation.

If a centrifugal pump is placed far above the liquid surface, it may require a suction lift to draw the liquid into the pump. This situation can lead to air entrapment, cavitation, and reduced efficiency, as these pumps do not perform well against suction head. Additionally, maintaining a robust supply of liquid to the pump ensures smooth operation, minimizes the risk of cavitation, and enhances reliability.

While considering other choices, easier maintenance, energy efficiency, and specific design limitations are less critical factors compared to the need for effective suction. Thus, the location of the pump is vital for its operational integrity and performance, emphasizing the importance of placing it close to or below the liquid level.