The function of a positioner is to manoeuvre a control valve; the valve is moved to a particular position. Positioners are used to maintain certain parameters such as temperature, flow and pressure. A pneumatic valve positioner is a type of positioner that is used with a control valve.
Pneumatic valve positioners are commonly utilised with pneumatic piston actuators. The control valve sends out a signal which is received by the pneumatic valve positioner. Upon receiving the signal, the positioner releases air pressure; this allows for great precision in the alignment of the valve’s position, in conjunction with an actuator.
Pneumatic valve positioners are mainly used in the oil & gas and manufacturing industries.
Functions of pneumatic valve positioners
Pneumatic valve positioners are used for the following reasons:
- They boost the resolution of control systems.
- They facilitate operation when the number in the actuator bench-set range is higher than 15psig.
- They enable the use of characteristic cams in rotary valves.
- They lessen the effects of valve stem packing friction.
- They assist in reducing seating friction in rotary valves.
- They enable distances between controllers and controller valves.