Pneumatic valves are used to control the flow of air in pneumatic systems. They are used in many applications, including machine tools and manufacturing processes, where they regulate the amount of air that flows through the system. There are many types of pneumatic valves, each designed for a specific purpose. But before diving into each one, let’s understand the concept of pneumatics.
Meaning of Pneumatics
When defining pneumatics, we need to mention that the word ‘pneuma’ means air which suggests that the power comes from the compressed air.
So, a pneumatic system is a system that uses compressed air to create motion and power. Compressed air can be used to move objects or to power small motors. Most pneumatic systems have a compressor, which creates the compressed air, and an air receiver tank, where the compressed air is stored.
How a Pneumatic System Works?
The way a pneumatic system works is pretty simple — it's just like a hydraulic system, except instead of using fluid (like oil), it uses air. You have an air compressor that pumps air into a tank or reservoir (called a "tank"), which stores the compressed air until you need it. Then you have valves that control how much of your stored compressed air goes into your device and where it goes when it's there. Let’s talk about pneumatic valves.
What is a Pneumatic Valve?
Pneumatic valves are the most important components in pneumatic systems. They can be used to control flow and pressure in pipes. These valves are a mediator between a compressor and a pneumatic actuator. They are also called directional control valves and their major goal is to control and regulate the airflow in the system.
The actuation element that causes the pneumatic valve to open or close can be activated in a variety of ways, including pneumatically, manually, electrically, or mechanically.
Types of Pneumatic Valves
Pneumatic valves can be classified
- Based on the system employed to open and close the ports
- Based on how many entry and exit points they have
- Based on each component's unique function
- Based on the position of the valve when it's in an inactive state
- Depending on the flow pathways or switching positions that they have
Let’s check the most common types of pneumatic valves:
Two-Way Pneumatic Control Valves
With the use of two ports that can be opened or closed, they transmit air in one direction. No air can pass through a closed valve if the ports are sealed. If the ports are open, air may pass from the first port through the valve in the opposite direction. These types of valves are used to control the flow of air in only one direction.
They have two positions – open and closed, which means they are always either letting air pass through or stopping it from passing through.
Three-Way Directional Control Pneumatic Valves
These types of valves can control the flow of air in two directions. A 3/2-way pneumatic control valve has three ports and two positions and can be used to control the flow of air. One port is for letting the air enter the valve, the second port is for allowing the air to leave the valve, and the third one acts as an exhaust port.
Four-Way Pneumatic Control Valves
The four-way pneumatic valve is similar to the three-way pneumatic valve but with an additional port that allows isolation from one side while allowing flow from another side at the same time. Four separate ports make up a four-way directional valve, two of which are connected to actuators, one to compressed airflow, and one of which is an exhaust passage. By having four ports, these valves can reverse the motion.
The most common configurations that show the number of ports and switching positions are the following — 2/2-way (two ports, two switching positions), 3/2-way, 4/2-way, 5/3-way, and 5/2-way.
Spring Offset Pneumatic Valve
With these valves, the airflow direction is shifted. Consider a two-way directional valve that can be either open or closed. An actuator moves a valve spool into place so that each port may determine whether it is in the open or closed state. A spring unwinds the valve spool, allowing the pneumatic valve to return to its original position.
As mentioned above, several types of pneumatic valves can be used in various applications. Double-check these valves before choosing the one that meets your industrial needs.