Understanding the Solenoid Valve and its Relation to Pneumatic Systems

Pneumatic Systems

Many industries use solenoid valves in their pneumatic systems to stop or regulate the condensed air stream or fluid of oil to different appliances. These valves are highly likely the most utilized components in the world of pneumatic systems. Not to mention, they are also useful for cylinder actuation — a larger type of industrial valve.

Solenoid valves may contain more than two ports and operate in different system functions. When it comes to determining their function, it can be identified through a symbol. However, the symbol does not contain any explanation about the valve’s construction. Solenoid valves can be energized in several ways, such as solenoid actuation or manual actuation.

Today, this article will give you further learnings about solenoid valves and their relation to pneumatic systems.

Solenoid Valve Design and Operation

Generally, solenoid valves have a reel-like blueprint which has a body made of aluminum. This aluminum has a cylindrical opening. The valve has several ports that are attached to the tube. The cylinder has a sliding pool with multiple seals together with its diameter. By means of pushing the spool to and fro through the cylinder’s body, several sockets are attached.

Making a zero leakage sealing can be tough with the design of the spool. Hence, solenoid valves often have a small leakage. Air pressure can pass through in the same direction with these kinds of valves, and the said movement is referred to as bidirectional. For the spool to move, it only requires less force since the air pressure has limited impact.

A lot of solenoid valves for pneumatic systems are managed internally under less air value. That being said, in most applications, a minimal air loss into the environment is acceptable. However, this should not be applicable to oil, water, and other media types. In addition, the materials of valves are greatly optimized for air utilization.

Oftentimes, the valve is created out of aluminum parts and seals. It’s already a known fact that other elements than air may cause valve corrosion and/or other chemical reactions.

Image source: https://www.ato.com/pneumatic-solenoid-valve-2-way-12v-24v-110v-220v

What are Bi-stable and Mono-stable Valves?

A bi-stable valve can be shifted by a transitory operation and will stay in such a position for a long time. Therefore, the valve will not revert to its initial position before the operation, if such operation is blocked or stopped. This type of valve often has a solenoid on each end. Per solenoid is in control for switching state individually. Bi-valves are also called double performing solenoid directional valves.

On the other hand, a mono-stable valve is supported by an elastic base position. By the time the valve will be actuated, it will switch to its active state. And, during the transmission of electrical power, the mono-valve will revert to its base position, again. These type of mono-stable valves are called single performing solenoid directional valves.

Different Types of Solenoid Valves

Solenoid directional valves are indicated with two digit numbers. The initial number displays the number of sockets there is in the valve. The second digit shows the state’s amount. This is how it should be, a 2/2-route valve includes two states as well as two ports, and a 5/2-route valve contains two states and five ports. Here are other directional valves and their respective details.

  • 2/2-route Valve – This is the most typical and basic valve type containing two states and two sockets and is referred to as shut-off valve. It is mainly utilized in pneumatic conveying systems & procedures where the air supply should be switched off periodically.

2/2-route valves can either be bi-stable or mono-stable in general. The bi-stable valves often have single solenoid. It is being pulse-controlled to shift from one state to another. These valve types are known as “latching.” 2/2-route valves in mono-stable can be opened and closed normally.

  • 3/2-route valve – Unlike the previous solenoid valve, this one has three sockets as well as binary states. These are used to regulate a cylinder in single-performance.  This type of valve is utilized to the entire single-performing cylinder. For proper venting, a third socket is necessary. 3/2-route valves can also be bi-stable or mono-stable.
  • 5/2-route valve – As the name implies, this type has five sockets as well as binary states. This solenoid valve is mainly utilized for controlling dual-performing cylinders since they require two external valve ports. Just like the rest of solenoid valves, 5/2-route valve is either bi-stable or mono-stable.
  • 5/3-route valve – Unlike the previously mentioned valves, this one has five sockets and three states. The main purpose of the state on the third position is to control or stop a dual-performing cylinder in a transitional position. 5/3-route valves are single-stable. They will revert to middle position when solenoids are at rest.

You need two solenoids in order to move the valve body from one state to another. There are three available variants of 5/3-route valves: with venting middle position, with a forced middle point as well as a closed middle point.

Image source: https://www.highgravitybrew.com/store/pc/3-Way-Valve-Stainless-1-2-NPT-p10207.htm


The entire pneumatic system plus the solenoid valve application can be puzzling especially for beginners. The purpose of this article is to give you valuable details on what you should do when handling solenoid valves, like the XHVAL angle pattern globe valve, in pneumatic systems.