In most process control applications, larger valves tend to be fitted with pneumatic actuators that provide significant positioning forces. In these situations, the positioner is used to precisely position the valve by filling the actuator with the corresponding amount of air, or by venting from the actuator. However, the volume of air required to achieve fast positioning in larger actuators (1,400–2,800-cm2 diaphragm areas) overwhelms normal positioners. To overcome such difficulties, this firm has developed a control package with a positioner and several volume boosters with different air-output capacities, which performs this task. Closing and opening times of less than 2 s can be achieved over the entire positioning range. — Samson Controls, Redhill, U.K.