Pneumatic Valves: Components and Functions
Pneumatic operated valves are essential devices used for starting, stopping, and controlling the flow of fluid or gas by regulating the supply of air to the pneumatic actuator through solenoid coils and positioners.
Major Components and Functions:
a) Valve (Butterfly, Ball, Gate, etc.):
The valve is positioned in-line with the pipeline of the same size and material of construction as the process pipeline. It can have flanged or threaded ends based on specific requirements.
b) Actuator:
The actuator converts pneumatic force from the air into mechanical rotation, allowing for precise control or on/off action of the valve.
c) Positioner (in Control Valves only):
In control valves, the positioner controls the input of air to the actuator in a controlled manner, matching the 0/4-20 mA signal received from the controller to achieve the desired set point.
d) Limit Switch:
The limit switch is a mechanical switch that rotates with the valve spindle, indicating the angle of rotation and providing electrical NO/NC contacts. It offers feedback to the control panel or PLC panel regarding the valve's position.
e) Solenoid Valves:
Solenoid valves are used to direct the flow of pneumatic air either directly to the actuator in the case of on/off valves or to the positioner in the case of control valves.
Understanding the components and functions of pneumatic valves is crucial for effectively controlling the flow of fluid or gas. By utilizing valves, actuators, positioners, limit switches, and solenoid valves, you can achieve accurate and reliable control in various industrial applications.
