Understanding the working principle of pneumatic control pneumatic valve

Working principle of the pneumatic control valve, pneumatic control pneumatic valve is compressed air as power source, the cylinder as actuator, and with the aid of electric pneumatic valve positioner, converters, solenoid pneumatic valve, pneumatic valve for attachment to drive the pneumatic valve, realize the switch quantity or proportion type adjustment, industrial automation control system receives the control signal to complete regulating the flow of pipeline medium, pressure, temperature and other process parameters. Pneumatic control valve is to control the characteristics of simple, quick response, and intrinsically safe, do not need another explosion protection measures. Pneumatic control valve action points gas open type and close type two kinds. Gas type ( 空气打开) Is when the film head air pressure increases, the pneumatic valve to increase the opening direction of the movement, when to input pressure limit, pneumatic valve in the fully open position. On the other hand, when the air pressure is reduced, pneumatic valve to close the direction of movement, when no input air, pneumatic valve full close.

so sometimes gas type pneumatic valve is also called fault closed type ( 失败关闭FC) 。 Type gas clearance ( 空气关闭) Movement direction is just the reverse of gas drive type. When the air pressure increases, the pneumatic valve to the closed motion directions; Air pressure decrease or not, the direction of pneumatic valve to open or fully open. So sometimes called fault open type ( 无法打开FO) 。 Pneumatic control valve of gas or gas close, usually by positive and negative effects of the actuator and the structure of the pneumatic valve state different assembly way.

gas-off choice is according to the process of production safety perspective to consider. When air cut off, the regulating pneumatic valve is in the closed position safety or open position?

, for example, a heating furnace combustion control, regulating pneumatic valve installed in the fuel pipe road, according to the chamber of a stove or furnace temperature or the temperature of the heated material in furnace exit to control the supply of fuel. At this time, appropriate chooses gas drive pneumatic valve safer, because once the air stop supply, pneumatic valve in the closed is more suitable than the pneumatic valve is fully open. If fuel gas source, pneumatic valve fully open, can make the heat excess risk. And as a use of cooling water cooling of heat exchange equipment, hot material in the heat exchanger heat exchange are cooled with water, regulating pneumatic valve installed on the cooling water pipe, use after heat exchange materials to control the cooling water temperature, the gas source is interrupted, adjust the pneumatic valve is in open position safer, appropriate chooses gas closed type ( The FO) Pneumatic valve adjustment.

pneumatic valve positioner is a major attachment of regulating pneumatic valve, pneumatic valve with pneumatic control greatly, it accepts the regulator output signal, and then to its output signal to control pneumatic valve, pneumatic control when regulating pneumatic valve action, pneumatic valve rod displacement and machinery through feedback to pneumatic valve positioner, pneumatic valve position condition through the electrical signal to the upper system. Pneumatic valve positioner according to its structure and working principle can be divided into pneumatic pneumatic valve positioner, electric - Pneumatic valve positioner and intelligent gas type pneumatic valve positioner.

pneumatic valve positioner can increase to adjust the output power of the pneumatic valve, reduce the number of control signal transmission lag, accelerate the pneumatic valve rod movement speed, to improve the linearity of the pneumatic valve, overcome the friction of the pneumatic valve stem and eliminate the influence of unbalanced force, so as to ensure the correct positioning of regulating pneumatic valve.