Valves are mainly used in the fields of petroleum, chemical industry, natural gas, tap water, steam, sanitation, food, district water supply, boilers, power stations, central air conditioning, etc.
Regulating valves are used to regulate the flow of operating variables, so they are called regulating valves. From the overall point of view of the control system, whether a control system is well controlled or not must be achieved by regulating valves. For the following reasons, regulating valves become very important.
1. The control valve is a throttle device, which belongs to the moving parts. Compared with the detection elements, transmitters and controllers, in the process of control, the control valve needs to constantly change the flow area of the throttle, so as to change the control variables to adapt to the changes of load or operating conditions. Therefore, higher requirements are put forward for the sealing, pressure resistance and corrosion of the control valve assembly. 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 movable parts of the control valve are the main causes of running, running, dropping and leaking. It not only wastes resources or materials, but also pollutes the environment and causes accidents.
The contact medium of the regulating valve material may be different from that of the testing element, so higher requirements are put forward for the corrosion resistance, strength and stiffness of the regulating valve.
3. The throttling of the control valve makes the energy consumed inside the valve. Therefore, the reasonable choice and consideration should be made between reducing the energy consumption, reducing the pressure loss of the control valve and ensuring the better control quality.
4. Regulating valves throttle fluids but also cause noise. For example, when the outlet pressure of the regulating valve is lower than the vapor pressure of the liquid, it causes flash; when the downstream pressure of the regulating valve is higher than the vapor pressure of the liquid, it causes cavitation. The noise caused by the control valve is related to the design of the flow path, the operating pressure and the characteristics of the controlled medium. Therefore, reducing noise and pressure loss put forward higher requirements for the control valve.
Fifth, the control valve has strong adaptability. It is installed in various production processes. The operation conditions of high temperature, low temperature, high pressure, large flow and small flow in the production process require that the control valve has various functions. The control valve can meet the requirements of different applications.
6. Detection components, transmitters and controllers have developed rapidly, and more manpower and material resources have been invested. Relatively speaking, it is generally believed that the structure of the control valve is simple, so the research and development of the control valve is relatively inadequate in manpower and material resources.