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