Which statement about a 4/2 valve is true?

• A. It has four ports and two positions, with only one port for the actuator.
• B. It can control two actuators.
• C. It has four ports and two positions, including two for supply/exhaust and two for the actuator.
• D. It has only two ports.

Answer: (C)

A 4/2 valve is a directional control valve with four ports and two positions. That means there are two ports that connect to the actuator (to drive extension and retraction) and two ports that handle supply and exhaust (pressure from the supply and venting to atmosphere). In one position, pressure from the supply flows to one actuator port while the other actuator port vents; in the other position, the flow paths swap, allowing the actuator to move in the opposite direction. This is exactly what the statement describing four ports, two positions, with two for supply/exhaust and two for the actuator conveys.