Pneumatic valves:

The actuator and adjustment mechanism of the valve pneumatic actuator are a whole, and there are two types of actuators: diaphragm type and piston type. The piston type has a long stroke and is suitable for occasions requiring greater thrust. The diaphragm travel 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, safety and explosion-proof, etc., it has a wide range of applications in power plants, chemical industry, oil refining and other production processes that require high safety.

The main advantages of pneumatic valves:

1. Accept continuous air signal and output linear displacement (after power-on/air conversion device, it can also receive continuous electrical signal), and some signals can output angular displacement after equipped with rocker arm.

2. There are positive and negative effects.

3. The movement speed is high, but the speed decreases when the load increases.

4. The output force is related to the working pressure.

5. High reliability, but the valve cannot be maintained after the air supply is interrupted (maintenance can be performed after adding a stop valve).

6. It is inconvenient to realize segment control and program control.

7. Simple maintenance and strong adaptability to the environment.

8. High output power.

9. With explosion-proof function.

Electric valve:

Electric valves are mainly used in power plants or nuclear power plants because high pressure water systems require smooth, steady and slow processes. The main advantage of electric valves is the high stability and constant thrust that the user can apply. The maximum thrust produced by the actuator can be as high as 225000kgf. Only hydraulic actuators can achieve such a large thrust, but hydraulic actuators are much more expensive than electric actuators. The anti-deviation ability of the electric valve is very good, and the output thrust or torque is basically constant, which can overcome the unbalanced force of the medium and realize the precise control of the process parameters, so the control accuracy is higher than that of the pneumatic actuator. If equipped with a servo amplifier, the positive and negative effects can be easily swapped, the position state of the signal shut-off valve (hold/fully open/fully closed) can be easily set, and when a fault occurs, it must be left in its original position. Pneumatic actuators cannot do this, and pneumatic actuators must rely on a combined protection system to achieve position retention.

The main disadvantages of electric valves are:

The structure is more complex and more prone to failure. Due to its complexity, the technical requirements for on-site maintenance personnel are relatively high; the operation of the motor generates heat. If the adjustment is too frequent, it is easy to cause the motor to overheat and generate thermal protection. This also increases the wear of the reducer; in addition, it runs slower. It takes a long time from the regulator output signal to the corresponding movement of the regulator valve to the corresponding position. This is where it is inferior to pneumatic and hydraulic actuators.