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Engineering ToolBox > PFD - Process Flow Diagram

The Process Flow Diagram - PFD, a schematic illustration of the system

A Process Flow Diagram - PFD - (or System Flow Diagram - SFD) shows the relationships between the major components in the system. PFD also tabulate process design values for the components in different operating modes, typical minimum, normal and maximum. A PFD does not show minor components, piping systems, piping ratings and designations.

A PFD should include:

• Process Piping
• Major equipment symbols, names and identification numbers
• Control, valves and valves that affect operation of the system
• Interconnection with other systems
• Major bypass and recirculation lines
• System ratings and operational values as minimum, normal and maximum flow, temperature and pressure
• Composition of fluids

This figure depict a small and simplified PFD:

System Flow Diagrams should not include:

• pipe class
• pipe line numbers
• minor bypass lines
• isolation and shutoff valves
• maintenance vents and drains
• relief and safety valve
• code class information
• seismic class information

• Example - Process Flow Diagram
• Piping & Instrumentation Diagram - P&ID?