Control valve is used to adjust the flow of operating variables, so it is called control valve. From the overall control system, whether a control system is well controlled or not must be achieved through control valve. Control valve becomes very important for the following reasons.

1. Control valve is a throttling device and belongs to a moving part. Compared with detection elements, transmitters and controllers, in the control process, the control valve needs to continuously change the flow area of the throttling part to change the manipulated variable to adapt to load changes or changes in operating conditions. Therefore, higher requirements are put forward for the sealing, pressure resistance and corrosion of the valve assembly of the control valve. For example, the seal will increase the friction of the control valve, increase the dead zone of the control valve, and cause the control quality of the control system to deteriorate.

2. The moving parts of the control valve are the main cause of running, bubbling, dripping and leakage. It not only causes waste of resources or materials, but also pollutes the environment and causes accidents. The contact medium of the control valve material may be different from the contact medium of the detection element, so higher requirements are put forward for the corrosion resistance, strength and rigidity of the control valve.

3. The throttling of the control valve consumes energy inside the valve. Therefore, it is necessary to reasonably choose and balance between reducing energy consumption, reducing the pressure loss of the control valve, and ensuring good control quality.

4. The control valve also causes noise while throttling the fluid. For example, when the outlet pressure of the control valve is lower than the vapor pressure of the liquid, flash evaporation is caused; when the pressure downstream of the control valve is higher than the vapor pressure of the liquid, cavitation is caused. The noise caused by the control valve is related to the design of the control valve flow path, operating pressure, and controlled medium characteristics. Therefore, reducing noise and reducing pressure loss put forward higher requirements for the control valve.

5. The control valve has strong adaptability. It is installed in various production processes. The operating conditions of high temperature, low temperature, high pressure, large flow, and small flow in the production process require the control valve to have various functions, and the control valve can adapt to the requirements of different applications.

6. Detection elements, transmitters, controllers, etc. are developing rapidly, and more manpower and material resources are invested. Relatively speaking, it is generally believed that the control valve has a simple structure, so the manpower and material resources invested in the research and development of the control valve are relatively insufficient.