Accessories for a globe control valve are components that enhance its functionality and are essential for automated control systems. These accessories typically include:
Positioners
A valve positioner is the most common accessory for a globe control valve. It's a device that precisely controls the valve's position by sending a proportional air signal to the actuator. This ensures the valve stem reaches the correct position, minimizing errors caused by friction or pressure changes. Positioners can be pneumatic, electro-pneumatic, or digital ('smart').
Air Filtration Pressure-Reducing Valve (Airset)
This accessory, often called an airset, is vital for pneumatic control valves. It filters and purifies the compressed air from the air compressor and then regulates the pressure to the specific, stable value required by the valve's actuator and positioner.
Solenoid Valves
A solenoid valve is an electromechanical device that uses an electric current to control the flow of air to the valve's actuator. It is used when the system needs to perform a specific action, such as a full open or full close, based on an electrical signal from a control system.
Position Transmitters
A position transmitter provides a remote indication of the valve's actual position. It converts the physical displacement of the valve stem into a proportional electrical signal (e.g., 4-20 mA) that can be sent back to a control room for monitoring.
Limit Switches
Limit switches are devices that signal when the valve has reached its full open or full closed position. They are used to provide feedback to the control system, confirming that the valve has completed its travel.
Volume Boosters (Quick Exhaust Valves)
A volume booster is a pneumatic relay that increases the flow capacity of the air signal to the actuator. This allows the valve to open or close more quickly, which is essential for applications requiring a rapid response time.
