SELECTING ACTUATORS FOR QUARTER-TURN VALVES - THE RIGHT ONE CAN IMPROVE FLOW-CONTROL AND REDUCE MAINTENANCE COSTS

Growth in the use of quarter-turn valves has produced a corresponding growth in the use of actuators for these valves. Actuator use is also increasing as a result of more and more plants using computers or automatic process control systems. The actuators provide cost benefits as well as more precise, positive control of the process. In specifying any actuator, the application requirements must first be determined. The actuator must complement the action side of the valve, thus the following factors must be considered: type and size of valve, media to be controlled, temperature, line pressure and maximum pressure differential across the valve, desired cycle time in second, and type of action, on-off or control. Next, consider the environment in which the valve and actuator will be used. The specifics of application will also dictate what actuator accessories will be needed. This article concentrates on ball and butterfly quarter-turn valves and provides guidelines on selecting the proper pneumatic or electric actuator to be used with them.