process flow diagram

Modern PFD of a plant for gas sweetening by amine absorption
Historical PFD from 1931 showing the Andrussow processA process flow diagram (PFD) is a diagram commonly used in engineering to indicate the general flow of plant processes and equipment. The PFD displays the relationship between major equipment of a plant facility and does not show minor details such as piping details and designations. Another commonly-used term for a PFD is a flowsheet.