What is the function of a flapper valve in a diaphragm pump?

A flapper valve serves the important function of preventing backflow in a diaphragm pump. This type of valve is designed to allow fluid to flow in one direction while blocking it from flowing back in the opposite direction. In diaphragm pumps, the flapper valve operates based on the differences in pressure created during the pumping cycle. When the diaphragm moves in one direction, the flapper valve opens to let the fluid in or out, depending on the configuration, and when the diaphragm moves back, the flapper closes to prevent any reverse flow. This action is crucial for maintaining efficiency and ensuring that the fluid is pumped effectively, without any loss caused by backflow. Other options presented do not align with the primary role of a flapper valve in this context.