Positioners for Industrial Valves and Dampers
The purpose of valve positioners is to control a butterfly, ball, gate, or globe valve's position such that a given process will achieve specific desired flow parameters. Positioners also control damper opening and closing. They perform this by analyzing the error between the desired valve position (as determined by the controller) and the actual valve position. Specialized sensors mounted on the valve stem or actuator shaft compare the magnitude of error between the control system setpoint and the real-time process value. The positioner's job is to provide a corrective output that is then sent electrically or pneumatically to a valve actuator. The corrective out moves the valve in a more-open or more-closed direction until the achievement of setpoint.
Positioners play a vital role as a control valve accessory and the interface between the control system and valves in ensuring the process loop's performance. The valve positioner manages the percent of the valves' opening, thereby varying the valve's flow rates. The valve orifice is controllable from completely shut or wide open to anywhere in between. An example of this type of positioning control will include mixing hot and cold water to achieve a specified downstream temperature requirement. Controlling the valve's opening and closing maintains process control parameters such as flow, pressure, level, and temperature.
Tri-State Technical Sales offers a full range of valve positioning equipment, including pneumatic, electric, electro-pneumatic, and smart digital positioners. Call them at 610-647-5700 or visit their website at https://tristatetechnicalsales.com.