Control valve, also known as control valve, is the main type of actuator. It can change fluid flow through power operation by receiving the control signal output from regulating control unit. Regulating valve generally by the implementing agencies and valves. If you press the actuator used by its power, the control valve can be divided into pneumatic, electric, hydraulic three, that is, compressed air as the power source of the pneumatic control valve, electric power to the electric control valve to liquid medium (Such as oil) pressure-powered electro-hydraulic control valve, in addition, according to their functions and characteristics of points, as well as solenoid valve, electronic, intelligent, field bus type regulating valve. Regulating valve body type selection There are many types of valve body, commonly used through a single seat, through two-seater, angle, diaphragm, small flow, tee, eccentric rotation, butterfly, sleeve, spherical and so on. In the specific choice, the following considerations can be made: (1) The shape of the valve spool is mainly based on the selected flow characteristics and unbalanced forces and other factors to consider. (2) Abrasion resistance When the fluid medium is a suspension containing high concentration of abrasive particles, the internal material of the valve should be rigid. (3) Corrosion Due to the media corrosive, try to choose a simple structure of the valve. (4) Medium temperature, pressure When the medium temperature, high pressure and changes, should use the valve core and valve seat material by temperature, pressure changes in small valves. (5) to prevent flash and cavitation flash and cavitation only produce liquid medium. In the actual production process, flash and cavitation will form vibration and noise, shorten the life of the valve, so the valve should be selected to prevent flash and cavitation. The choice of control valve actuator In order to work properly with the control valve, with the implementation of agencies to produce enough output force to ensure a high degree of sealing and valve opening. For double-acting pneumatic, hydraulic, electric actuator, there is usually no return spring. The size of the force has nothing to do with its direction of operation, so the key to choosing an actuator lies in knowing the maximum output force and the torque of the motor. For single-acting pneumatic actuators, the output force is related to the opening of the valve, and the presence of force on the regulating valve will also affect the kinematic behavior, thus requiring a force balance across the opening of the regulating valve. The type of implementing agencies to determine the output of the implementing agencies to determine, according to process requirements of the use of the environment, select the appropriate implementing agencies. For on-site explosion-proof requirements, pneumatic actuators should be used. From the energy-saving aspects, should try to use electric actuator. If the adjustment of high precision, hydraulic actuator can choose. Such as power plant transparent speed control, refinery catalytic reactor temperature control and so on. The mode of action of the regulating valve The mode of action of the regulating valve is selected only when the pneumatic actuator is selected. The mode of action is formed by the positive and negative action of the actuator and the positive and negative action of the valve. There are four types of combination that is positive (air-off type), positive and negative (air-open type), anyway (air-open type), anti-anti (anti-off type) Open and Qi off two. For the control valve mode of action, mainly from three aspects: a) process safety; b) the characteristics of the media; c) to ensure product quality, economic loss is minimal. Control valve, also known as control valve, is the main type of actuator. It can change fluid flow through power operation by receiving the control signal output from regulating control unit. Regulating valve generally by the implementing agencies and valves. If you press the actuator used by its power, the control valve can be divided into pneumatic, electric, hydraulic three, that is, compressed air as the power source of the pneumatic control valve, electric power to the electric control valve to liquid medium (Such as oil) pressure-powered electro-hydraulic control valve, in addition, according to their functions and characteristics of points, as well as solenoid valve, electronic, intelligent, field bus type regulating valve. Regulating valve body type selection There are many types of valve body, commonly used through a single seat, through two-seater, angle, diaphragm, small flow, tee, eccentric rotation, butterfly, sleeve, spherical and so on. In the specific choice, the following considerations can be made: (1) The shape of the valve spool is mainly based on the selected flow characteristics and unbalanced forces and other factors to consider. (2) Abrasion resistance When the fluid medium is a suspension containing high concentration of abrasive particles, the internal material of the valve should be rigid. (3) Corrosion Due to the media corrosive, try to choose a simple structure of the valve. (4) Medium temperature, pressure When the medium temperature, high pressure and changes, should use the valve core and valve seat material by temperature, pressure changes in small valves. (5) to prevent flash and cavitation flash and cavitation only produce liquid medium. In the actual production process, flash and cavitation will form vibration and noise, shorten the life of the valve, so the valve should be selected to prevent flash and cavitation. The choice of control valve actuator In order to work properly with the control valve, with the implementation of agencies to produce enough output force to ensure a high degree of sealing and valve opening. For double-acting pneumatic, hydraulic, electric actuator, there is usually no return spring. The size of the force has nothing to do with its direction of operation, so the key to choosing an actuator lies in knowing the maximum output force and the torque of the motor. For single-acting pneumatic actuators, the output force is related to the opening of the valve, and the presence of force on the regulating valve will also affect the kinematic behavior, thus requiring a force balance across the opening of the regulating valve. The type of implementing agencies to determine the output of the implementing agencies to determine, according to process requirements of the use of the environment, select the appropriate implementing agencies. For on-site explosion-proof requirements, pneumatic actuators should be used. From the energy-saving aspects, should try to use electric actuator. If the adjustment of high precision, hydraulic actuator can choose. Such as power plant transparent speed control, refinery catalytic reactor temperature control and so on. The mode of action of the regulating valve The mode of action of the regulating valve is selected only when the pneumatic actuator is selected. The mode of action is formed by the positive and negative action of the actuator and the positive and negative action of the valve. There are four types of combination that is positive (air-off type), positive and negative (air-open type), anyway (air-open type), anti-anti (anti-off type) Open and Qi off two. For the control valve mode of action, mainly from three aspects: a) process safety; b) the characteristics of the media; c) to ensure product quality, economic loss is minimal.