How a 3/2 Directional Valve Works?
The Directional Control Valves are also known as a solenoid valve and spool valve. As we all know about these valves have a spool inside the body that regulates the fluid or pneumatic air in various directions. During the selection of the Directional Control valve, you have to make sure what is your requirement? Do you really require a 3 position control valve?
Normally valves are used to allow and stop the fluid flow. The same as faucets, the best example of a 2-way valve that manually operated to allow the water and stop the water flow. But in the directional control valve, there is a twist. 3 position directional control valves used to allow the fluid flow, to stop the fluid flow, and to change the direction of fluid flow. The directional control valve comes up in 2 way, 3 way, 4 way & 5 way. All these are available in 2 positions and 3 positions.
Normally Open & Normally Closed
The 2-way directional valves are called spring return valves as known NO for normally open, and NC for the normally closed condition. A 2-way directional control valve has two ports- called inlet and outlet. When the inlet port is blocked in an inactive position called Normally Closed and when the inlet port is active in an inactive position called Normally Open. NC valve required to energize to open the inlet ports, this feature saves energy.
A spool has been used as a barrier in directional valves, because of this, these valves also known as spool-type valves. The spool connected to a solenoid coil from one end, and at the other end, there is a spring in the spring return valve. When the coil energizes, the spool moves up towards the spring and closes the ports in the normally open valve, and when the coil de-energizes the spring on the other end pushes back the spool to its earlier position and ports start flowing the fluid.
3/2 Directional Control Valve
As the name reflects that 3/2 Directional Control Valve has three ports and after the slash shows the positions. In a 3/2 Directional Control valve, the spool’s movement decides the direction of the fluid flow.
If we have a 3/2 Directional control valve (fig 1.1), we get three ports, one at the opposite side (port-A) on the body and the two ports at the same side (port- P & R). Here the spool plays the key role with the same sided ports. It allows only one port to be open at a time and close the other one while the opposite-sided port -A always remains open.
So we can open the ports as we per the need by sliding the spool. In normal condition (fig 1.1) port- P is closed and port -A connected to port- R, while we push the button of the solenoid coil or energize the solenoid coil, the spool moves towards the spring, and port- P opens up and the port- A connects to port- P.
How to read 3/2 Directional Valve Symbol?
In every Directional Control valve, you can see the symbolic image of its working phenomena. (Fig1.3) In that symbolic image, there are squares, those squares show the positions. The first left square represents the normal position of the valve and the rest of the others are showing working positions. As the above example port- P connected to Port- A while Port- R close and at the second position Port- R connected to port- R and closed the port- P.
Now you can easily understand the rest of the Directional control valves.
Airmax Pneumatics Ltd is one of the leading Pneumatic Valve Manufacturers in India. They offer Directional Control Valves in a variety of models and specifications.