What is the purpose of the discharge check valve on a centrifugal pump?

The discharge check valve on a centrifugal pump has the primary purpose of preventing backflow in the piping system when the pump is not operating. By ensuring that fluid does not flow back through the impeller and into the pump, the check valve protects the pump from potential damage that could occur if the impeller were to rotate in reverse. This reverse spinning can lead to issues such as wear or even structural failure of the impeller and other components inside the pump.

In addition to protecting the pump, the check valve maintains the pump's prime, ensuring that it is still filled with liquid and ready to start again without the need for re-priming. This is crucial for maintaining operational efficiency and preventing downtime.

In contrast to the other options, bleeding the volute or ensuring a flooded suction are not functions of the discharge check valve. Bleeding the volute typically pertains to air removal for operational efficiency, while a flooded suction relates to the water level in the supply tank or reservoir that feeds the pump, not something the check valve is designed to manage. Additionally, preventing cavitation is primarily achieved through proper pump sizing and system design rather than through the use of a check valve.