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

The primary purpose of a check valve on the discharge side of a pump is to prevent backflow when the pump is off. This type of valve is designed to allow fluid to flow in one direction only, which protects the pump and the piping system from potential damage caused by reverse flow. When the pump is not operating, the check valve closes, ensuring that the water or fluid does not move back into the pump or upstream into the system. This functionality is critical in maintaining system efficiency and integrity, especially in applications where backflow could lead to contamination or loss of prime in the pump.

Regulating flow speed, maintaining pressure, and allowing for emergency drainage focus on different aspects of fluid dynamics and system operation but do not directly relate to the specific role of a check valve in preventing backflow. Each of those aspects may be important in other contexts but are not the primary function of a check valve.