A process flow diagram (PFD) is a diagram used in chemistry and process engineering to indicate the general flow of plant processes and equipment. The chemistry PFD displays the relationships between major equipment of a plant facility and does not show minor details such as piping details and designations. As the diagram shows, a process flow diagram of multiple process units within a large industrial plant will usually contain less detail and is called block flow diagrams or schematic flow diagrams. Chemical PFD displays the real scheme of the chemical process and illustrates the connections between the basic equipment as well as the overall structure of pipelines and other supporting equipment.
