Any idea on how this type of pneumatic solenoid works? I know that NC is normally closed, NO normally open, but not sure how air flows? Thanks!

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  • $\begingroup$ It's not clear if you are showing the electrical or pneumatic connections. $\endgroup$ Jan 4, 2017 at 22:42
  • $\begingroup$ pneumatic connection is shown in the image $\endgroup$
    – Transistor
    Jan 4, 2017 at 22:53

1 Answer 1


When no voltage is applied to the solenoid, air will flow between port 2 'Common' and port 3 'Normally Open,' but not to port 1 'Normally Closed.' When voltage is applied, air will flow between port 2 and port 1, but not to port 3. We could likely assume that the direction of air flow is intended to be from port 2 to ports 1 & 3, but it isn't a guarantee and it may not matter to the valve. Note that in pneumatic and hydraulic circuits, normally closed and normally open have the opposite definition as in electrical circuits. For a valve, closed means not passing air/oil, whereas for a relay closed means passing electrons.

A more standard diagram for this valve would be #3 in the image below: Example valve diagrams

Although it's worth noting that the 'T' designation implies a hydraulic valve, and numeric port designations are more common for pneumatic valves.


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