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.

在氣路(或液路)上來說，兩位三通電磁閥具有1個進氣孔(接進氣氣源)、1個出氣孔(提供給目標設備氣源)、1個排氣孔(一般安裝一個消聲器，如果不怕噪音的話也可以不裝。兩位五通電磁閥具有1個進氣孔(接進氣氣源)、1個正動作出氣孔和1個反動作出氣孔(分別提供給目標設備的一正一反動作的氣源)、1個正動作排氣孔和1個反動作排氣孔(安裝消聲器)。 對于小型自動控制設備，氣管一般選用8~12mm的工業膠氣管。

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.

在電氣上來說，兩位三通電磁閥一般為單電控(即單線圈)，兩位五通電磁閥一般為雙電控(即雙線圈)。線圈電壓等級一般采用DC24V、AC220V等。 兩位三通電磁閥分為常閉型和常開型兩種，常閉型指線圈沒通電時氣路是斷的，常開型指線圈沒通電時氣路是通的。

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.

常閉型兩位三通電磁閥動作原理：給線圈通電，氣路接通，線圈一旦斷電，氣路就會斷開，這相當于“點動”。

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".

常開型兩位三通單電控電磁閥動作原理：給線圈通電，氣路斷開，線圈一旦斷電，氣路就會接通，這也是“點動”。

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".

兩位五通雙電控電磁閥動作原理：給正動作線圈通電，則正動作氣路接通(正動作出氣孔有氣)，即使給正動作線圈斷電后正動作氣路仍然是接通的，將會一直維持到給反動作線圈通電為止。 給反動作線圈通電，則反動作氣路接通(反動作出氣孔有氣)，即使給反動作線圈斷電后反動作氣路仍然是接通的，將會一直維持到給正動作線圈通電為止。這相當于“自鎖”（即所謂的記憶功能）。 基于兩位五通雙電控電磁閥的這種特性，在設計機電控制回路或編制PLC程序的時候，可以讓電磁閥線圈動作1~2秒就可以了，這樣可以保護電磁閥線圈不容易損壞。

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.