What device converts pneumatic energy into mechanical motion?

The device that converts pneumatic energy into mechanical motion is the pneumatic actuator. Pneumatic actuators utilize compressed air to create movement, allowing them to perform various actions, such as opening or closing valves, moving machinery, or operating tools. When compressed air is introduced to the actuator, it expands and applies force on a piston or diaphragm, resulting in linear or rotary motion. This function makes pneumatic actuators particularly useful in automation and control systems where rapid movement is desired.

In contrast, a hydraulic actuator operates on hydraulic energy rather than pneumatic energy, using liquid under pressure for movement. A pressure switch is implemented to monitor pressure levels within a system and does not produce mechanical motion. A flow meter measures the flow rate of liquids or gases, but it also does not facilitate mechanical motion. Thus, the correct answer highlights the specific role of pneumatic actuators in the conversion of pneumatic energy to mechanical motion.