Knowledge-based Design of PI Diagrams Exemplified for Pumps in Chemical Plant. To date, computer-aided design for flowsheets has focussed on drawing procedures and reports extracted from these drawings. Today’s software technology offers important potential which has still not been fully exploited, e.g. for the design of PI diagrams as front-end application of CAD systems. PI diagrams for process units can be designed by means of knowledge-based systems. The input information which has to be supplied by the process engineer comprises e.g. physico-chemical properties, process conditions and start-up and shut-down procedures. The results are PI diagrams as well as the documentation of the design criteria and operating instructions if manual operations on site are necessary. The potential of knowledge-based computer-aided design of PI diagrams is demonstrated in the case of pumps in chemical plant.