A pneumatic system is very common in many industrial facilities, and it uses compressed air for energy transmission and energy control for equipment such as presses, forging presses, and blast cleaners. Some of the most important components of a pneumatic system are the pneumatic valves. In this post, we take a closer look at pneumatic valves to answer one primary question, “How do they work?”

What is a Pneumatic Valve?

A pneumatic valve is a device used to control/ modulate airflow in a pneumatic system. It is one of the wide ranges of components that help with "dosing and guiding" functions using a system of locking and regulating elements. This is why you might find the valves being referred to as “mediators” between the compressors (source) and actuators in a pneumatic system. 

When still at the definition, it is crucial to appreciate that you can only get top-notch results by selecting the right ones. Therefore, you might want to start by understanding your pneumatic system to understand and order the model recommended by the manufacturer.

The Main Types of Pneumatic Valves

To demonstrate how pneumatic valves work; here is a closer look at the different categories:

Two-Way, Two-Position Valves

These pneumatic valves are made of two ports that are connected via a passage and can be easily opened or closed via a plunger. In most cases, the valves are activated using electrically run solenoid shifts that move the valve poppet or spool to guide airflow. These pneumatic valves are preferred in many industrial facilities because they can easily be turned on or off to isolate, interlock, or connect various parts.

Three-Way, Two-Position Valves 

As the name suggests, these valves are designed using three ports via passages in their bodies. The valves work by pressurizing and exhausting one outlet port to control one cylinder or pilot the next. See the demonstration of a 3-way, two positon valve demonstratio below:

To operate, the 3-way valves direct pressurized air to the side of the cylinder with cap-ends. When the valve shifts the spool to the other extreme, it bocks air and pressure to stop the actuator. 

The three-way valves might be paired to run double-acting cylinders, helping to replace 4-way valves. Also, you should consider coupling 3-way pneumatic valves to your cylinder ports to cut down on back-pressure and air pressure drop in lines. If you are running highly cyclic applications, 3-way, two-position valves can also come in handy.

Four-Way, Two-Position Valves

These valves come with 4-5 ways featuring 2-3 positions. If it is a 2-position valve, it features two distinct flow paths in every position that actuate/reverse rotary actuators, reverse cylinders, or run bidirectional motors. The spool is used to direct flow from the pressure port while others simultaneously port exhaust to the atmosphere. Here is a pictorial demonstrating the operation of a four-way, two-position pneumatic valve.

If you are using the 5-port version of the 2-position valve, it comes with five individual ports with different configurations, such as two pressure ports and two varying exhaust ports. In the former, for example, the pneumatic valve might be used for supplying pressure to actuate cylinders for high clamping force but deliver lower pressure when releasing the clamp. Using lower pressure can help in saving energy. 

Four-Way, Three-Position Valves

This category of pneumatic valves is also available in five-port positions. The commonest center positions for the valves are the “exhaust center” and “all ports blocked.” The two extreme positions of the valve are the power positions of the valve for controlling the movement of the actuator. Then, the center position is made to meet the requirements, such as letting the actuator float or locking it. 

As you can see, hydraulic valves, whether used in mobbing or stationary equipment, such as hydraulic pumps, are very useful in determining how effective your work will be. Remember also to ensure they are fitted properly for enhanced safety and do the regular maintenance of your facility for better performance.