What is the main difference between a Process Flow Diagram (PFD) and a Piping and Instrumentation Diagram (P&ID)?

The main difference between a Process Flow Diagram (PFD) and a Piping and Instrumentation Diagram (P&ID) is the level of detail they provide about a process plant. A PFD provides a simplified overview of the process, showing the major equipment, process streams, and key process parameters, such as flow rates, temperatures, and pressures. It focuses on the overall flow of materials and energy through the process. A P&ID, on the other hand, provides a much more detailed representation of the process, including all the piping, equipment, instrumentation, control loops, and safety devices. It shows the specific connections between equipment, the types and sizes of pipes, the locations of valves and instruments, and the control strategies used to operate the process. P&IDs are used for detailed design, construction, operation, and maintenance of the process plant, while PFDs are used for process understanding and optimization.