Pneumatic Accessories For Pneumatic ActuatorBlog,Valves Study | Jun.24.2021
Electro-pneumatic valve positioner:
The valve positioner is the main accessory of the pneumatic actuator. It is used in conjunction 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 is realized in accordance with the signal from the regulator position it correctly.
Under the following circumstances, a positioner is required:
- When the medium pressure is high and the pressure difference is large;
- When the caliber of the regulating valve is large (DN>100);
- High temperature or low temperature control valve;
- When it is necessary to increase the operating speed of the regulating valve;
- When using standard signals to operate non-standard spring actuators (the spring range is outside of 20～100KPa);
- When used for split-range control;
- When the valve realizes the reverse action (the air-to-close type and the air-to-open type are interchanged);
- When the flow characteristics of the valve need to be changed (the positioner cam can be changed);
- When there is no spring actuator or piston actuator, it is necessary to achieve proportional action;
- When using electrical signals to operate pneumatic actuators, power must be distributed to the pneumatic valve positioner.
When the system needs to achieve program control or two-position control, it needs to be equipped with a solenoid valve. When the solenoid valve is selected, 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. It can be used “Normally open” or “normally closed”. If you need to increase the capacity of the solenoid valve to shorten the action time, you can use two solenoid valves in parallel or use the solenoid valve as a pilot valve in combination with a large-capacity pneumatic relay.
Air filter pressure reducing valve:
Air filter pressure reducing valve is an accessory in the industrial automation instrument. 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 pneumatic instruments, solenoid valves, Air supply and voltage stabilizing device for cylinders, spraying equipment and small pneumatic tools.
Travel switch (responder):
The travel switch reflects the two extreme positions of the valve switch and sends out an indication signal at the same time. Based on this signal, the control room can betray the switch state of the valve in order to take corresponding measures.
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