• The working principle of self-operated regulating valves

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The working principle of self-operated regulating valves

  • Feb 12, 2019
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A self-operated regulating valve is also called a self-operated control valve. It is a new type of regulating valve. As the name implies, it does not need external power supply and secondary instrument. It relies on the pressure and temperature of the medium flowing through the valve to drive the valve to work automatically, that is, the pressure and temperature serve as energy. The feedback signal (pressure, differential pressure, temperature) at the output of the valve is transmitted to the actuator through the signal tube, and the valve flap is driven to change the opening degree of the valve, so as to to achieve the purpose of regulating pressure, flow and temperature.

According to the structure and function, the self-operated regulating valve can be generally divided into: self-operated temperature regulating valve, self-operated pressure regulating valve, self-operated flow regulating valve, etc., which can be applied to most fluid media for automatic adjustment. It can effectively convert the internal energy of the fluid medium into a driving force, thereby controlling the valve to open and close.

The working principle of self-operated regulating valve:
When the medium fluid flows from the front of the valve through the valve plug and seat, it was throttled and converted to post-valve pressure. Then, through the pipeline, the medium fluid flows into the upper chamber and acts on the top tray. At this time, the force generated will be equal to the reaction force of the spring. This determines the relative position of the valve seat and valve plug, thus the post-valve pressure is controlled. When the pressure behind the valve increases, the force acting on the top plate also increases correspondingly, so that the valve plug is closed to the position of the valve seat. In this case, the interval between the valve plug and the valve seat is reduced, the flow resistance becomes higher, and the  post-valve pressure decreases. Until the acting force on the top plate is balanced with the reaction force of the spring, the post-valve pressure drops to a preset value. When the pressure behind the valve is lowered, the direction of action is opposite to that previously mentioned. This is the working process of the self-operated regulating valve.

For the traditional control valve, the self-operated regulating valve does not require external energy. The output signal of the regulated medium can effectively adjust the properties of the fluid medium, which not only saves the expense of a lot of extra accessories, but also reduces the use of energy, catering to the national call for energy conservation and emission reduction.