The working principle of pneumatic valve uses the characteristics of compressed air to push multiple groups of combined pneumatic pistons in the actuator to move, transfer force to the beam and inner curve track, drive the air core spindle to rotate, and the compressed air disc is sent to each cylinder to change the air inlet and outlet position to change the spindle rotation direction. According to the requirements of the rotating torque required by the load (valve), the number of cylinder combinations can be adjusted to drive the load (valve) to work. The two position five way solenoid valve is usually used together with the double acting pneumatic actuator. The two positions are controllable: open close. The five way solenoid valve has five channels for ventilation, one of which is connected with the air source, two of which are connected with the inlet and outlet of the external air chamber of the double acting cylinder, and two of which are connected with the inlet and outlet of the internal air chamber. For the specific working principle, refer to the working principle of the double acting pneumatic actuator. As more and more control methods and means, there are many methods to control pneumatic actuators in actual industrial production and industrial control.

一、阀门可靠性 我们习惯的认为气动阀门可靠性高，电动阀门的可靠性差。但新一代电动阀门执行机构采用新电路集成技术，摈弃之前的致命弱点后，使得执行机构可平均使用5—10年，从而达到或超过气动阀门的使用年限。因此从可靠性来讲，两种类型阀门各有优点。

1、 Valve reliability We are used to thinking that the reliability of pneumatic valves is high, but the reliability of electric valves is poor. However, the new generation of electric valve actuator adopts new circuit integration technology. After discarding the previous fatal weakness, the actuator can be used for 5-10 years on average, thus reaching or exceeding the service life of pneumatic valve. Therefore, in terms of reliability, both types of valves have advantages.

二、现场动力源 在防爆要求非常高的场合大都选用气动阀门执行机构--气动阀门优点之一是本质防爆，而缺点也是显而易见—需建立较为完善的气动机构，增加了配置费用。而电动阀门执行机构可以就地取材，在防爆要求不高，配备气源又不方便时电动阀门。

2、 Pneumatic valve actuators are mostly used for on-site power sources in places with very high explosion-proof requirements -- one of the advantages of pneumatic valves is that they are intrinsically explosion-proof, while the disadvantages are also obvious -- more perfect pneumatic mechanisms need to be established, which increases the configuration cost. The actuator of electric valve can use local materials. When the explosion-proof requirements are not high and the air supply is not convenient, the electric valve can be used.

三、对比 电动阀门执行机构与气动阀门执行机构+阀门定位器技术指标基本相同。两种类型产品不论国产还是进口的均不相上下。而气动阀门需配置空压站等气源设施，所以选用电动阀门在上有优势。

3、 Price comparison The technical indicators of electric valve actuator and pneumatic valve actuator+valve positioner are basically the same. The prices of the two types of products, both domestic and imported, are comparable. The pneumatic valve needs to be equipped with air compressor station and other air source facilities, so the selection of electric valve has advantages in price.

四、出力明显 执行机构的选配是根据阀门的类型和允许压差来决定的。因此具体的选配要根据实际情况来确定，这一点需要灵活掌握。

4、 The selection of actuator with obvious output is determined by the type of valve and allowable differential pressure. Therefore, the specific selection should be determined according to the actual situation, which needs to be flexibly mastered.

五、防火防爆 在防火防爆层面，气动执行机构+阀门定位器要远远优于电动执行机构： 1.只有少数电动执行机构可生产成为防爆系列。 2.高易燃、易爆等特殊场合通常不允许采用电动执行机构。

5、 Fire and explosion protection In the aspect of fire and explosion protection, pneumatic actuator+valve positioner is far superior to electric actuator: 1. Only a few electric actuators can be produced into explosion-proof series. 2. Electric actuators are generally not allowed to be used in highly flammable, explosive and other special occasions.