What is a Process Flow Diagram (PFD) and what information does it contain?

A Process Flow Diagram (PFD) is a schematic representation of a process showing the major equipment, process streams, and basic control philosophy. It contains: major equipment with names and numbers, process piping (no utility piping), stream flow rates, compositions, temperatures and pressures, major control loops, and stream data tables. PFDs are used for process understanding, design calculations, and communication between disciplines. They differ from P&IDs by showing less instrumentation detail and excluding utility systems, minor equipment, and detailed piping.