First, we will talk about a family of fairly simple air valves designated as 2/2 air valves.
- the compressed air valve has two working ports – one for air supply in, and another for air supply to the application. Air piloted 2/2 valves may also have a third air port for the pilot signal to shift the valve.
- it can only be shifted into one of two positions – either it's opened (something flows through it) or it is closed (nothing flows through it)
- it is normally open (NO) or normally closed (NC) in its un-actuated, resting state
Next is the 3/2 air valve. As noted earlier, the first number is the number of working ports that the valve has, and the second number indicates the number of positions that the valve has.
Next in the series is the 4/2 air valve. As the applications using compressed air get more complex, so too will the air valves that control them
The 4/2 valve will have four working ports, and two positions. There will be one supply port that brings compressed air from the compressor to the air valve. There will be two ports that can be plumbed from the valve to two separate applications, or to one air cylinder, and the last port in the 4/2 valve will be an exhaust port which will allow air to travel back through the valve to atmosphere alternately from one of the working (application) ports or the other.
The 5/2 compressed air valve functions similarly to the 4/2. It will have one compressed air supply port, two working or application ports to supply air to the application, and two exhaust ports through which air will flow to atmosphere alternately from each of the application ports, in turn. Click here for more information on the 5/2 configured air valve and then click here to learn how to draw a 5/2 air valve
An even more complex air valve is the 5/3. The 5/3 valve will have five ports (2 exhaust ports, 2 working or power ports and 1 supply port), just like the 5/2 valve.
Regardless of the type of air valve your application demands, all of them will have a valve actuator, or valve actuators. If you have experience with compressed air valves, you'll be comfortable with the term manual actuator, This simply means that the valve is actuated by an operator (person) that pushes at button, moves a lever, toggles a switch, and so on.
Please note that I define an operator as a person that actuates a valve, and an actuator (sometimes noted as external actuator) as the device on the valve that actually shifts it. This is my personal definition, and you may find that other people have different terms for the same thing. Make sure when you are talking to folks about valves that you understand their terms, will you?
The first two in the valve designation 2/2 refers to the number of ports that valve has, and the second two refers to the number of positions that valve will have.