Pneumatic valve is the most common fluid control equipment in industrial pipeline, which is mainly composed of pneumatic actuator and valve. The valve is driven by compressed clean air to control the flow and shutoff of pipeline medium. The execution speed is very fast, and it is usually used for quick shutoff. Pneumatic valve is usually equipped with various accessories, such as solenoid valve, air source treatment triplet, limit switch, positioner, control box, etc., to realize local control and remote centralized control. If the solenoid valve is a necessary configuration for the two-position valve that only needs to be opened and closed, the solenoid valve can control the opening/closing of the pneumatic valve through excitation/degaussing.

在气路(或液路)上来说，两位三通电磁阀具有1个进气孔(接进气气源)、1个出气孔(提供给目标设备气源)、1个排气孔(一般安装一个消声器，如果不怕噪音的话也可以不装。两位五通电磁阀具有1个进气孔(接进气气源)、1个正动作出气孔和1个反动作出气孔(分别提供给目标设备的一正一反动作的气源)、1个正动作排气孔和1个反动作排气孔(安装消声器)。 对于小型自动控制设备，气管一般选用8~12mm的工业胶气管。

In terms of air circuit (or liquid circuit), the two-position three-way solenoid valve has 1 air inlet (connected to the air supply), 1 air outlet (provided to the air supply of the target equipment), 1 air outlet (generally installed with a muffler, if it is not afraid of noise, it can not be installed. The two-position five-way solenoid valve has 1 air inlet (connected to the air supply), 1 positive acting air hole and 1 negative acting air hole (respectively provided to the air supply of the target equipment) One positive action exhaust hole and one negative action exhaust hole (install muffler). For small automatic control equipment, the gas pipe is generally 8~12mm industrial rubber gas pipe.

在电气上来说，两位三通电磁阀一般为单电控(即单线圈)，两位五通电磁阀一般为双电控(即双线圈)。线圈电压等级一般采用DC24V、AC220V等。 两位三通电磁阀分为常闭型和常开型两种，常闭型指线圈没通电时气路是断的，常开型指线圈没通电时气路是通的。

Electrically, the two-position three-way solenoid valve is generally single electric control (i.e. single coil), and the two-position five-way solenoid valve is generally double electric control (i.e. double coil). The coil voltage level generally adopts DC24V, AC220V, etc. The two-position three-way solenoid valve is divided into two types: normally closed type and normally open type. Normally closed type means that the air circuit is disconnected when the coil is not powered on, and normally open type means that the air circuit is open when the coil is not powered on.

常闭型两位三通电磁阀动作原理：给线圈通电，气路接通，线圈一旦断电，气路就会断开，这相当于“点动”。

The action principle of the normally closed two-position three-way solenoid valve: energize the coil and connect the air circuit. Once the coil is powered off, the air circuit will be disconnected, which is equivalent to "inching".

常开型两位三通单电控电磁阀动作原理：给线圈通电，气路断开，线圈一旦断电，气路就会接通，这也是“点动”。

The action principle of the normally open two-position three-way single electric control solenoid valve: energize the coil and disconnect the air circuit. Once the coil is powered off, the air circuit will be connected, which is also "inching".

两位五通双电控电磁阀动作原理：给正动作线圈通电，则正动作气路接通(正动作出气孔有气)，即使给正动作线圈断电后正动作气路仍然是接通的，将会一直维持到给反动作线圈通电为止。 给反动作线圈通电，则反动作气路接通(反动作出气孔有气)，即使给反动作线圈断电后反动作气路仍然是接通的，将会一直维持到给正动作线圈通电为止。这相当于“自锁”（即所谓的记忆功能）。 基于两位五通双电控电磁阀的这种特性，在设计机电控制回路或编制PLC程序的时候，可以让电磁阀线圈动作1~2秒就可以了，这样可以保护电磁阀线圈不容易损坏。

The operation principle of the two-position five-way double electric control solenoid valve: if the positive action coil is powered on, the positive action air circuit is connected (the positive action air hole has air). Even if the positive action coil is powered off, the positive action air circuit is still connected, and will continue until the negative action coil is powered on. If the reaction coil is powered on, the reaction air circuit is connected (the reaction air hole has air). Even if the reaction coil is powered off, the reaction air circuit is still connected and will remain until the positive action coil is powered on. This is equivalent to "self-locking" (so-called memory function). Based on this characteristic of the two-position five-way dual-control solenoid valve, when designing the electromechanical control circuit or compiling the PLC program, it is enough to make the solenoid valve coil act for 1-2 seconds, which can protect the solenoid valve coil from being easily damaged.