Short description of e!Sankey 2.5: A software to easily create Sankey diagrams. A Sankey diagram is a directional flow chart where the width of the arrows is proportional to the flow quantity. Sankey diagrams are a useful way of visualizing material flows, energy or costs. If you are a chemical, environmental or process engineer, a professional in quality management, logistics or finance, you can use e!Sankey diagrams to display flow quantities in production systems.