The regulating valve locator is the main accessory of pneumatic actuators, which is used in conjunction with pneumatic actuators to improve the position accuracy of the valve, overcome the influence of stem friction and medium imbalance force, and ensure that the valve is correctly positioned according to the signal from the regulator.
In the following situations, a locator is required:
1. When the medium pressure is high and the pressure difference is large;
2. When the diameter of the regulating valve is large (DN>100);
3. High temperature or low temperature regulating valve;
4. When it is necessary to increase the operating speed of the regulating valve;
5. When using standard signals and operating non-standard spring actuators (within the spring range of 20-100KPa);
6. When used for split range control;
7. When reversing the valve action (switching between air close and air open);
8. When it is necessary to change the flow characteristics of the valve (the cam of the locator can be changed);
9. Spring free execution
When the mechanism or piston actuator needs to achieve proportional action;
10. When using electrical signals to operate pneumatic actuators, it is necessary to distribute power to the pneumatic valve locator.
   
Electromagnetic valve:
When the system needs to implement program control or two position control, electromagnetic valves need to be equipped. When selecting an electromagnetic valve, in addition to considering the AC and DC power supply, voltage, and frequency, attention must be paid to the relationship between the action type of the electromagnetic valve and the regulating valve. It can be matched with a "normally open" or "normally closed" type.
If it is required to increase the capacity of the solenoid valve to shorten the action time, two solenoid valves can be used in parallel or combined with a large capacity pneumatic relay as a pilot valve.

Pneumatic relay:
Pneumatic relay is a power amplifier that can send air pressure signals to distant places, eliminating lag caused by signal pipeline elongation. It is mainly used between on-site transmitters and regulating instruments in the central control room, or between regulators and on-site regulating valves. Another function is to amplify or reduce signals.
    
Converter:
The converter is divided into a pneumatic electric converter and an electro-pneumatic converter. Its function is to achieve the conversion of certain relationships between pneumatic and electrical signals. It is mainly used to convert 0-10mA or 4-20mA electrical signals or 0-100KPa gas signals into 0-10mA or 4-20mA electrical signals when manipulating pneumatic actuators with electrical signals.
    

Air filtration pressure reducing valve:
Air filtration pressure reducing valve is an accessory in industrial automation instruments. Its main function is to filter and purify the compressed air from the air compressor, and stabilize the pressure at the required value. It can be used as a gas supply and pressure stabilizing device for various pneumatic instruments, solenoid valves, cylinders, spraying equipment, and small pneumatic tools.
    

Self locking valve (holding valve):
A self-locking valve is a device that maintains the valve position. When the pneumatic control valve experiences a malfunction in the air source, the device can cut off the air source signal, keeping the pressure signal of the membrane chamber or cylinder in the state at the moment before the malfunction, thereby maintaining the valve position at the position before the malfunction, playing a protective role.
    
Valve position transmitter
When the regulating valve is far away from the control room, in order to accurately understand the opening and closing position of the valve without being on site, a valve position transmitter needs to be equipped. That is, the displacement of the valve opening mechanism is converted into an electrical signal according to a certain pattern and sent to the control room. This signal can be a continuous signal reflecting any opening of the valve or a reverse action of the valve locator.
     
Travel switch (communicator)
The travel switch is a device that reflects the two extreme positions of the valve switch and sends indicator signals at the same time. The control room can use this signal to trip the valve switch status in order to take corresponding measures.