Flow paths should be coded (e.g., by color and/or width) to indicate important information.
Additional Information:
For example, color can be used to differentiate process flow paths: blue may be used to code water lines; white, steam lines; and yellow, oil lines. In general, features of the flow path that change (e.g., the open/close status of valves) should be coded so as to be more salient than static features.