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:

Process Flow Diagram - 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

Related Topics

  • Documentation - Documentation of process control systems - Block Flow Diagrams (BFD), Process Flow Diagrams (PFD), Piping and Instrumentation Diagrams (P&ID) and more
  • Design Strategies - Piping systems and design strategies - documentation, P&ID, flow diagrams - capacities and limits
  • Process Control - Instrumentation and process control systems - engineering and documentation

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