Control Valves Accessories
Control Valves accessories (From Samson) are those essential elements without which we cannot expect control valve applications in industries. One of the most common final control elements in industrial control systems is the control valve. Control valves work to restrict the flow of fluid through a pipe at the command of an automated signal, such as the signal from a loop controller or logic device (such as a DCS or PLC). Some control valves are designed for discrete (on/off) control of fluid flow, while others are designed to throttle fluid flow.
To understand further an actuator (to operate a valve) classification based on controlling source or medium is given as follows-
- Pneumatic Actuators
- Hydraulic Actuators
- Electric Actuators (motor operated)
- Electro-hydraulic Actuators
- Gas Powered Actuators
Pneumatic actuated control valves are most widely used type of control valves in industries. A basic requirement as valve accessories is a pressure regulator which provides desired pneumatic supply to additional accessories such as-I/P converter, positioner, solenoid valve, Booster relay etc. Function of different type of valve accessories is given as follows-
- Provides regulated air supply to other accessories.
Air filter Regulator (AFR)-
- Provide filtered and regulated air supply to other accessories.
Filter Regulator Lubricator (FLR/ FRL)-
- FLR/ FRL combines a filter, regulator, and lubricator into one component to keep pneumatic systems in optimal working condition.
- Receives controller output signal and Coverts into controlled pneumatic signal to actuator.
- Receives controller output signal and Coverts into controlled hydraulic signal to actuator.
- Receives controller signal and monitor valve position accurately and based on error signal (difference between controller output and position feedback) manipulates air input to actuator.
- Receives discrete output from controller and make valve either fully open or close.
- Manage ESD trip function too.
- Provide volume boosting action i.e. Increase the air volume to fasten valve opening / closing speed.
Air Lock relay/ Valve-
- Used to hold air pressure in control valve actuator, in case failure of air supply.
- Used to release air immediately to quick close or quick open the valve with no time.
- Provide valve actual on-off state (discrete signal) to controller such as PLC, DCS etc.
Valve Position transmitter-
- Provide valve actual position feedback (analog signal) to controller such as PLC, DCS etc.