Valve actuators are mainly used in power plants or nuclear power plants because of the need for a smooth, steady and slow process in high-pressure water systems. The main advantage of the electric actuator is a high degree of stability and the user can apply a constant thrust, the maximum actuator thrust can be as high as 225000kgf, to achieve such a large thrust only hydraulic actuators, hydraulic actuators cost more than electric Much higher. Anti-deviation ability of electric actuator is very good, the output thrust or torque is basically constant, can be very good to overcome the imbalance of media to achieve accurate control of process parameters, so the control accuracy than the pneumatic actuator to high. If equipped with servo amplifier, you can easily achieve the exchange of positive and negative effects, but also can easily set off signal valve state (keep / fully open / close), and failure, we must stay in place, this is Pneumatic actuators can not do that, the pneumatic actuator must rely on a combination of protection systems to achieve Paul bit.
Electric actuator shortcomings are:
The structure is more complex and more prone to failure, and because of its complexity, the technical requirements of on-site maintenance personnel are relatively higher; the motor runs to generate heat; if the adjustment is too frequent, the motor may be overheated and generate thermal protection; meanwhile, Will also increase the reduction gear wear; the other is to run slower, a signal output from the regulator to the control valve to move to that corresponding position, the need for longer time, which is not as good as its pneumatic, hydraulic execution Place for the device
Pneumatic valves
Actuator valve actuator and adjusting mechanism is a unified whole, its implementing agencies have two types of film and piston. Piston stroke long, suitable for applications requiring greater thrust of the occasion; the film stroke is small, can only directly drive the valve stem. As the pneumatic actuator has the advantages of simple structure, large output thrust, stable and reliable operation, safe explosion-proof, etc., it is widely used in the production processes with high safety requirements such as power plants, chemical engineering and oil refining.
The main advantages of pneumatic actuators:
Accept the continuous gas signal, the output linear displacement (plus power / gas conversion device, you can also accept the continuous electrical signal), and some coupled with the rocker, you can output angular displacement.
Have positive and negative reaction function.
Moving fast, but slowing as load increases.
Output pressure and operating pressure.
High reliability, but the gas source can not be maintained after the valve is interrupted (plus retention valve can be maintained).
Inconvenience to achieve segmentation control and process control.
Maintenance easy maintenance, good adaptability to the environment.
Output power larger.
With explosion-proof features.
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