A schematic representation of a process or part of a process that converts raw materials to products through the various unit operations. It typically uses a symbolic representation for the major items of equipment such as storage vessels, reactors, and separators, process piping to and from the equipment, as well as by-pass and recirculation lines, and the principal flow routes. Key temperatures and pressures corresponding to normal operation are included, as well as equipment ratings, minimum and maximum operational values. Material flows and compositions are included. It may also include important aspects of control and pumping, as well as any interaction with other process equipment or flows. The design duties or sizes of all the major equipment are also featured, which can collectively provide a comprehensive representation of the process. It is also known as a system flow diagram. Compare flowsheet; engineering line diagram.