How is the flow of a centrifugal pump primarily controlled?

The primary method for controlling the flow of a centrifugal pump is through the use of a discharge valve. By throttling this valve, the flow rate of the liquid being pumped can be adjusted. When the valve is partially closed, it creates resistance against the flow, thereby increasing pressure and reducing the flow rate. This is a straightforward and commonly used method in many systems to fine-tune the output of the pump without affecting its operational integrity.

Adjusting the impeller speed might also influence flow, but it is not the primary means for controlling it in practice. Similarly, altering the power supply can change the pump's performance but usually is not utilized as a primary control method. Changing the pump casing is not a typical method for flow control either; instead, it is more related to structural or capacity alterations and does not offer dynamic control of flow rates during operation.