What is the definition of a pneumatic controls operate by? Pneumatic controls are devices that use compressed air or gas to drive and control mechanical operations. They are commonly used in industrial settings when low cost, reliable, and consistent force needs to be applied in a repetitive manner. Pneumatic systems operate by the production of compressed air or gas, which is then used to move the components of a mechanical system or equipment. This is done by the use of an actuator, which is a device that converts energy from one source into mechanical motion. The actuator is controlled by the use of valves, which regulate the air pressure and the direction and velocity of the motion. Valves are also used to regulate the amount of air pressure that is applied to the actuator, allowing for more precise control over the motion. Pneumatic controls are an efficient and cost-effective way of controlling mechanical operations and are often used in many industrial applications.