How does atmospheric pressure make a suction piston pump work?

A suction piston pump operates by utilizing atmospheric pressure to move fluid. When the pump's piston is raised, it creates a partial vacuum within the cylinder. Because the pressure inside the cylinder is lower than the pressure of the surrounding environment, the external atmospheric pressure forces the fluid into the cylinder through an inlet valve.12

A check valve is typically employed to prevent the fluid from flowing back out of the pipe once it has entered the cylinder. As the piston continues its cycle, the fluid is then permitted to escape through an outlet valve. It is important to note that because this process relies on atmospheric pressure, it is limited in its reach; it can only force water to a maximum height of approximately 34 feet (10 meters). For applications requiring greater lift, engineers utilize force pumps, which rely on the mechanical force applied directly to the piston rather than atmospheric pressure alone.12