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Hi, this is the Industrial Control Assistant. As we all know, control valves are one of the most widely used intelligent devices in industrial applications today. In the field of industrial process automation, control valves act as the final control elements that receive control signals from control units and use mechanical force to adjust process parameters such as flow rate, pressure, temperature, and liquid level. Control valves generally consist of an actuator and a valve. Based on their stroke characteristics, control valves can be divided into straight-stroke and angle-stroke types ； Based on the power source used by their associated actuators, and according to their functions and characteristics, they are divided into three types: linear characteristic, equal percentage characteristic, and parabolic characteristic. Control valves are suitable for media such as air, water, steam, various corrosive substances, slurry, and oils. Control valves and accessories include: pneumatic control valves, electric control valves, self-acting control valves, manual control valves, pneumatic diaphragm actuators, electric actuators, electrical valve positioners, electric valve control modules, etc. Based on their power source, control valves can be divided into three categories: pneumatic, electric, and hydraulic. Pneumatic and electric types are the most commonly used in the production process. The development trends of control valves are mainly intelligence, standardization, miniaturization, rotation, and safety. The intelligentization of control valves began earlier abroad, and a large number of such products are now available on the market. Chinese manufacturers also attach great importance to research in this area. The advantages of intelligent control valves include compatibility with computers, improved reliability, reduced failure rates, as well as a simplification of the variety of control valves available and the requirements for their use. The intelligent valve positioner possesses all the functions of a conventional valve positioner, while also enabling improvements in the dynamic and static characteristics of control valves and enhancing their control accuracy. Intelligent modules are used to adjust the parameters of the controlled system, which helps to reduce the variety of control valves required and simplifies their manufacturing process. Therefore, intelligent valve positioners will become important auxiliary devices for control valves and be widely used in the coming period. In a control system, a control valve receives control signals from a regulator in order to adjust the flow rate of the controlled medium. The regulated parameter, namely the controlled variable, is maintained within the required range, thereby achieving automation of the production process. The proper selection and use of control valves are extremely important issues in automated production. At the production site, control valves directly regulate the process medium. Especially in situations involving high temperatures, high pressures, low temperatures, strong corrosivity, highly toxic substances, flammability, explosiveness, leakage risks, high viscosity, or crystallization tendencies, improper selection and use of such valves can pose difficulties for production automation, lead to a decline in the quality of regulation, and even cause serious production accidents. The above covers the current development status of control valves. Going forward, we will discuss topics such as their working principles and applications, as well as information on other industrial automation products. Stay tuned!