The final program requirement defines the conditions for which three stack lights should be set.
In each case, the feed flow rate to the Ball Mill is used to determine the light status.
The green stack light should be set if the flow rate is between 20 and 75 pounds per minute.
The red stack light should be on at a flow rate of less than 20 pounds per minute.
If neither stack light should be energized, a yellow stack light is illuminated.