Selection of Valve Electric Actuator Models
Sep 26,2022Read More
The regulating valve positioner is the main accessory of the pneumatic actuator. It is used together with the pneumatic actuator to improve the position accuracy of the valve, overcome the influence of the friction force of the valve stem and the unbalanced force of the medium, so as to ensure that the valve can follow the signal from the regulator to achieve correct positioning.
1. Solenoid valve of regulating valve
When the system needs to achieve program control or two-position control, it needs to be equipped with a solenoid valve. When choosing a solenoid valve, in addition to considering the AC and DC power supply, voltage and frequency, the relationship between the solenoid valve and the regulating valve must be paid attention to, and the "normally open" or "normally closed" type can be used. 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 the solenoid valve can be used as a pilot valve in combination with a large-capacity pneumatic relay.
2. Pneumatic relay of regulating valve
Pneumatic relay is a kind of power amplifier, which can send the air pressure signal to a far place and eliminate the lag caused by the lengthening of the signal pipeline. It is mainly used between the field transmitter and the regulating instrument in the central control room, or between the regulator and the field regulating valve, and another function is to amplify or reduce the signal.
3. Converter of regulating valve
The converter is divided into gas-electric converter and electric-gas converter. Its function is to realize the mutual conversion of a certain relationship between gas and electric signals. It is mainly used to convert 0～10mA or 4～20mA electrical signal into 0～100KPa gas signal when operating pneumatic actuator with electrical signal.
4. Air filter pressure reducing valve
The air filter 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 for various types of pneumatic instruments and solenoid valves, air cylinder, spraying equipment and air supply and voltage stabilizer for small pneumatic tools.
5. Self-locking valve of regulating valve (retaining valve)
A self-locking valve is a device that maintains the valve position. When the air source fails, the device can cut off the air source signal, so that the pressure signal of the membrane chamber or the cylinder is kept in the state of the moment before the failure, so that the valve position is also maintained at the position before the failure. to hold position.
6. Valve position transmitter of regulating valve
When the regulating valve is far from the control room, in order to accurately understand the opening and closing position of the valve without on-site, it is necessary to equip a valve position transmitter, that is, the displacement of the valve opening is converted into an electrical signal and sent to the control room according to a certain rule. The signal can be a continuous signal reflecting any opening of the valve, or it can be considered as the reverse action of the valve positioner.
7. Stroke switch of regulating valve (returner)
The travel switch reflects the two extreme positions of the valve switch and sends out an indication signal at the same time. The control room can judge the switch state of the valve according to this signal and take corresponding measures.
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