Three-Position Spool Valve Symbol Let's look at a 3-position valve. With this 3-position valve, the black middle flow box shows the flow path when the NEITHER actuator is active, and the springs are holding the valve in the middle position. We should only count the ports in a single box once per symbol. For example, in the 3-position valve, there are three boxes that show the three possible positions, but the valve has five physical ports. So, the valve will be called a 5/3 solenoid valve. Watch