Which component in a centrifugal pump prevents the reverse flow of liquid?

In a centrifugal pump, the component that effectively prevents the reverse flow of liquid is the check valve. This device is designed to allow fluid to flow in one direction only, thus blocking any backflow that could occur due to changes in pressure or fluctuations in the system. By doing so, the check valve maintains the priming of the pump and ensures that the fluid is directed to the intended discharge point without the risk of returning to the inlet.

While the impeller is crucial for generating the flow and pressure within the pump, it does not inherently prevent reverse flow. The recirculation line is typically used for maintaining flow and regulating temperature or pressure but does not act as a barrier to backflow. The volute casing helps guide the fluid in a specific direction after it has been pumped but does not provide the one-way flow functionality that is characteristic of a check valve. Thus, the check valve is the definitive component ensuring that the liquid does not flow back into the pump, safeguarding the efficiency and reliability of the entire system.