Final answer:
The black arrows inside the squares of a 3/2 way valve symbol show the direction of flow for the controlled medium, which helps in understanding how the valve operates within the system and which paths are taken during different valve positions.
Step-by-step explanation:
In the context of 3/2 way valve symbols, the black arrows inside the squares typically indicate the direction of flow for the medium being controlled by the valve, such as air or hydraulic fluid. These arrows show the position of the valve and the path that the medium will take when the valve is in a particular position. Valves are essential components in many engineering systems and are used to control the flow and pressure of fluids and gases in a control system.
For example, in a pneumatic system, if the arrow points from the inlet port to an outlet port, it indicates that when the valve is actuated to that position, the air will flow from the inlet to that specific outlet. Conversely, if the arrow points from an outlet port to the exhaust port, it would mean that the air at the outlet port will be exhausted out of the system when the valve is in that position.