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、閥門可靠性 我們習慣的認為氣動閥門可靠性高，電動閥門的可靠性差。但新一代電動閥門執(zhí)行機構采用新電路集成技術，擯棄之前的致命弱點后，使得執(zhí)行機構可平均使用5—10年，從而達到或超過氣動閥門的使用年限。因此從可靠性來講，兩種類型閥門各有優(yōu)點。

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、現(xiàn)場動力源 在防爆要求非常高的場合大都選用氣動閥門執(zhí)行機構--氣動閥門優(yōu)點之一是本質防爆，而缺點也是顯而易見—需建立較為完善的氣動機構，增加了配置費用。而電動閥門執(zhí)行機構可以就地取材，在防爆要求不高，配備氣源又不方便時電動閥門。

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、價格對比 電動閥門執(zhí)行機構與氣動閥門執(zhí)行機構+閥門定位器技術指標基本相同。兩種類型產品不論國產還是進口的價格均不相上下。而氣動閥門需配置空壓站等氣源設施，所以選用電動閥門在價格上有優(yōu)勢。

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、出力明顯 執(zhí)行機構的選配是根據(jù)閥門的類型和允許壓差來決定的。因此具體的選配要根據(jù)實際情況來確定，這一點需要靈活掌握。

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 在防火防爆層面，氣動執(zhí)行機構+閥門定位器要遠遠優(yōu)于電動執(zhí)行機構： 1.只有少數(shù)電動執(zhí)行機構可生產成為防爆系列。 2.高易燃、易爆等特殊場合通常不允許采用電動執(zhí)行機構。

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.