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Description of the advantages and disadvantages of electric valves and pneumatic valves

Electric valve
Valve electric actuators are mainly used in power plants or nuclear power plants because of the need for a smooth, stable and slow process in high pressure water systems. The main advantages of the electric actuator are the high stability and the constant thrust that the user can apply. The maximum actuator can generate up to 225,000 kgf of thrust. Only the hydraulic actuator can achieve such a large thrust, but the hydraulic actuator is more expensive than the electric actuator. A lot higher. 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 imbalance force of the medium and achieve accurate control of the process parameters. Therefore, the control accuracy is better than that of the pneumatic actuator. high. If a servo amplifier is used, the positive and negative interchange can be easily realized, and the state of the off-signal valve position (hold/full-open/full-off) can be easily set, and when the fault occurs, it must stay in the original position. Pneumatic actuators do not, pneumatic actuators must be secured by means of a combined protection system.
The main disadvantages of electric actuators are:
The structure is more complicated, it is more prone to failure, and due to its complexity, the technical requirements for on-site maintenance personnel are relatively higher; the motor runs to generate heat, if the adjustment is too frequent, it is easy to cause the motor to overheat and generate thermal protection. It will also increase the wear on the reduction gear; in addition, it will run slowly, and it will take a long time to output a signal from the regulator and move to the corresponding position in response to the valve response. This is not as good as pneumatic or hydraulic actuation. The place of the device.
Pneumatic valves
The actuator and adjustment mechanism of the valve pneumatic actuator are unified and the actuators are available in both diaphragm and piston types. The long piston stroke is suitable for applications requiring a large thrust; the diaphragm stroke is small and can only directly drive the valve stem. Because the pneumatic actuator has the advantages of simple structure, large output thrust, stable and reliable action, and safety and explosion-proof, it is widely used in power plants, chemical industry, oil refining and other production processes with high safety requirements.
The main advantages of pneumatic actuators:
It accepts continuous gas signals and outputs linear displacement (continuous electrical signals can be received after power-up/gas conversion device). Some can be equipped with a rocker arm to output angular displacement.
There are positive and negative functions.
The movement speed is large, but the speed will be slower when the load increases.
The output force is related to the operating pressure.
High reliability, but the valve can not be maintained after the air supply is interrupted (can be maintained after the retaining valve is added).
It is inconvenient to implement segmentation control and program control.
It is easy to maintain and maintain, and has good adaptability to the environment.
The output power is large.
With explosion-proof function.

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