Drying is a mass transfer process consisting of the removal of water or another solvent by evaporation from a solid, semi-solid or liquid. This PFD shows the drying equipment . Though its concepts are sometimes applied to other processes, it is most commonly employed in chemical engineering and process engineering. It can be used to document, improve, or model a new process. A Process Flow Diagram can be used for a variety of reasons. 1. To document a process for better comprehension, quality control, and employee training. 2. To make a process more efficient and repeatable by standardizing it. 3. To examine a process in order to increase its efficiency. It aids in the identification of redundant stages, bottlenecks, and other inefficiencies. Download EdrawMax and start creating PFD diagrams.