A pneumatic 3/2 valve has how many ports and how many positions?

• A. It has four ports and three positions
• B. It has three ports and two positions
• C. It has two ports and three positions
• D. It has three ports and three positions

Answer: (B)

In pneumatics, the slash notation on a valve tells you how many ports and how many positions it has. A three-port arrangement includes a pressure supply port, an output port to the actuator, and an exhaust port. The two positions mean there are two spool states the valve can hold, giving two different flow paths. In one state, pressure goes to the actuator while the exhaust is available; in the other state, the actuator is vented to exhaust (and the flow path changes accordingly). This is why a 3/2 valve is described as having three ports and two positions. If you see other numbers, they indicate different configurations—four ports would be a 4/2, two ports would be a 2/2, and three ports with three positions would be a 3/3.