Comparison and analysis of advantages and disadvantages between electromagnetic valve and pneumatic valve

Electric valve
Valve actuators are mainly used in power plants or nuclear power plants because high pressure water systems require a smooth, stable and slow process. The main advantages of the electric actuator are the high stability and the constant thrust that the user can apply. The thrust of the maximum actuator can be as high as 225000kgf, and the only hydraulic actuator can reach such great thrust, but the cost of the hydraulic actuator is much higher than that of the electric actuator. The anti deviation ability of the electric actuator is very good. The thrust or torque of the output is basically constant. It can overcome the unbalanced force of the medium and achieve the accurate control of the process parameters, so the control precision is higher than that of the pneumatic actuator. If the servo amplifier is used, the reciprocal function of the positive and negative functions can be easily realized, and the state of the broken signal valve position (hold / all open / all off) can be easily set, while the fault must stay in situ, which is not done by the pneumatic actuator, and the pneumatic actuator must use a set of combined protection system to protect the position.
The main shortcomings of the electric actuator are as follows:
The structure is more complex and more prone to failure, and because of its complexity, the technical requirements for the site maintenance personnel are relatively higher; the motor operation should produce heat, if the adjustment too frequent, it will cause the motor to overheat, produce thermal protection, and also increase the wear and tear of the deceleration gear wheel; in addition, the operation is slow, It takes a long time to output a signal from the regulator to the response of the regulating valve and move to the corresponding position, which is not as good as the pneumatic and hydraulic actuator.
Pneumatic valve
The actuator and regulating mechanism of valve pneumatic actuators are unified. The actuator has two types: membrane type and piston type. Piston stroke length is suitable for occasions requiring larger thrust, while thin film travel is smaller and can only directly drive the stem. Because the pneumatic actuator has the advantages of simple structure, large output thrust, stable and reliable action, and safety and explosion protection, it is widely used in the production process of high safety requirements in the power plant, chemical industry and oil refining.
The main advantages of pneumatic actuator:
A continuous gas signal is accepted and the output of a linear displacement (after a power / gas conversion device is also accepted by a continuous signal), and the angular displacement can be output after some of the rocker arms are fitted.
There is a positive and reverse function.
The mobile speed is large, but the speed will slow down when the load increases.
The output force is related to the operating pressure.
The reliability is high, but the valve can not be maintained after the gas source is interrupted.
It is inconvenient to realize piecewise control and program control.
The maintenance and maintenance is simple, and the adaptability to the environment is good.
The output power is large.
It has the function of explosion-proof.