A single-seat control valve is an industrial field instrument consisting of a control valve body and various electric actuators. It accepts 4-20mA or pulse signals from the controller for closed-loop control, achieving automatic control of parameters such as flow rate, pressure, temperature, and liquid level. Intelligent electric actuators can be selected, enabling digital transmission with DCS and PLCs to form a more intelligent control system. Electric control valves are available with 220V and 380V power supplies, and their flow characteristics include equal percentage, linear, and fast. Compared to pneumatic control valves, electric control valves offer advantages such as energy saving (consuming electricity only during operation), environmental friendliness (no carbon emissions), and quick and convenient installation (no need for complex pneumatic pipelines and air pump workstations). They are widely used in industrial automation systems in power, chemical, metallurgical, environmental protection, water treatment, light industry, and building materials sectors.
Single-seat control valves are divided into single-seat diaphragm control valves and single-seat piston control valves. They use compressed air as a power source and a diaphragm or piston cylinder as the actuator. They are driven by accessories such as electric valve positioners, converters, solenoid valves, and position-holding valves to achieve on/off or proportional regulation. They receive control signals from industrial automation control systems to regulate various process parameters such as flow rate, pressure, and temperature of pipeline media. The characteristics of pneumatic control valves are simple control, fast response, and inherent safety, requiring no additional explosion-proof measures. The cost of pneumatic control valves is also lower than that of electric control valves. In chemical and petrochemical industries, pneumatic control valves have unparalleled advantages over electric control valves.
The main structural types of single-seat control valves are: single-seat, sleeve-type, double-seat, and cage-type.
The main types of single-seat control valves are: three-way, angle, high-temperature, low-temperature, and bellows-type.