The regulating valve positioner is the main accessory of the pneumatic actuator, which is used in conjunction with the pneumatic actuator to improve the position accuracy of the valve, overcome the influence of stem friction and medium imbalance, and ensure that the valve is correctly positioned according to the signal from the regulator.

Positioners are required in the following situations:
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 or low temperature regulating valve;
4. When it is necessary to increase the operating speed of the regulating valve;
5. When operating non-standard spring actuators with standard signals (within the spring range of 20-100KPa);
6. When used for split range control;
7. When the valve is activated in reverse (air closed and air open switching to each other);
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 positioner.
Electromagnetic valve:
When the system needs to achieve 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 electromagnetic valve and the action type of the regulating valve, which can be matched with the "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 in combination 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 the lag caused by the extension of signal pipelines. 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:
Converters are divided into gas-electric converters and electro-pneumatic converters, whose function is to convert certain relationships between pneumatic and electrical signals. They are 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:
The air filtering pressure reducing valve is an accessory of 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 the air supply source and pressure stabilizing device for various pneumatic instruments, solenoid valves, cylinders, spraying equipment and small Pneumatic tool.
Self locking valve (holding valve):
A self-locking valve is a device that maintains the valve position. When the air supply fails, the pneumatic control valve can cut off the signal of the air supply, keeping the pressure signal of the membrane chamber or cylinder in the state immediately before the failure, thus enabling