Material flow analysis is bases on the law of mass conservation. Unfortunately there is no such thing like a law of volume conservation. Volumes could me compressed or expanded. For example think of waste going into a press. The mass stays the same but the volume coming out will be smaller than the volume going in.
Here's what you have to do: Enter the density (for water = 1t/m³) of each flow in your model. In combination with the volume information STAN will calculate the according mass flows, balance your model and calculate the missing volumes flows.
