The difference between the pneumatic control valves and electric adjusting valves and selection

Pneumatic control valves and electric adjusting valves difference and use with compressed air as power source, pneumatic control valve with pneumatic actuator, electric regulating valve is made up by electric actuators and regulating valve connection. It is not difficult to see the pneumatic control valve and the choice of electric control valve actuator is difference. Down in the face of pneumatic control valve and electric regulating valve on the power, use, maintenance, and other aspects were compared. Pneumatic control valve, gate valve pneumatic actuators actuators and regulating mechanism is a unified whole, the actuators are pneumatic diaphragm and pneumatic piston type two kinds. Piston stroke length, suitable for a greater thrust required; And pneumatic diaphragm stroke is lesser, can directly drive the valve rod. Due to the actuator has a simple structure, export thrust large, action is stable and reliable, and safe explosion-proof, pneumatic control valve in power plants, chemical industry, oil refining, such as the safety requirements of high production process has a wide range of applications. The main advantage of the pneumatic control valve: continuous gas signal, the output linear displacement ( After add electricity/gas conversion device, also can accept the continuous electrical signal) , some with rocker arm, but the output angular displacement. Have a positive, the reaction function. Movement speed, but the load is increased speed will slow down. Output force related to the operating pressure. High reliability, but after air break valve door cannot keep ( The position of valve can keep) 。 Inconvenience to implement piecewise control and program control. Maintenance is simple and good adaptability to environment. The output power is larger. With functions of explosion-proof. Electric control valves, electric valves electric actuator is mainly used in power plant or nuclear power plants, because in the high pressure water system needs a smooth, stable and slow process. The main advantage of electric actuators is a high degree of stability and the user can be used of constant thrust, maximum actuators that generates the thrust can be as high as 225000 KGF, can achieve only so big thrust hydraulic actuators, but the cost is higher than the electric hydraulic actuators. Electric actuator deviates from the resistance is very good, the output of the thrust or torque is basically constant and can be very good to overcome the medium unbalanced force, to achieve accurate control of process parameters, so the control accuracy is higher than pneumatic actuators. If with servo amplifier, can easily achieve positive and negative role reversal, also can easily set off valve position signal status ( Keep/open/close) And failure, must remain in situ, which is less than pneumatic actuators, pneumatic actuators must use a set of integrated protection system to achieve the position. Electric regulating valve faults mainly include: structure is complex, are more likely to happen malfunction, and because of its complexity, the technical requirements of maintenance personnel on the spot is relatively high; Motor running to generate heat, if the regulation is too frequent, easily cause motor overheating, thermal protection, it will also increase the wear reduction gear; Another is running slowly, from the regulator output a signal to the regulating valve response and movement to the corresponding position, need a long time, this is not as good as pneumatic, hydraulic actuator. The late operation and maintenance cost electric regulating valve pneumatic is much higher.