A depiction of the flow of materials through a process, including any rework or repair operations; also called a process flow chart.
A 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. Typically, process flow diagrams of a single unit process will include the following:
* Process piping
* Major bypass and recirculation lines
* Major equipment symbols, names and identification numbers
* Flow directions
* Control loops that affect operation of the system
* Interconnection with other systems
* System ratings and operational values as minimum, normal and maximum flow, temperature and pressure
* Composition of fluids
Process flow diagrams of multiple process units within a large industrial plant will usually contain less detail and may be called block flow diagrams or schematic flow diagrams.