Process Flow Diagram

A process flow diagram (PFD) is a diagram commonly used in engineering to indicate the general flow of plant processes and equipment. The PFD displays the relationship between major equipment of a plant facility and does not show minor details such as piping details and designations. Another commonly-used term for a PFD is a flowsheet.
Typically, process flow diagrams of a single unit process will include the following:
    • Process piping
    • Major bypass and recirculation lines
    • Major equipment symbols, names and identification numbers
    • Flow directions
    • Control loops that affect operation of the system
    • Interconnection with other systems
    • System ratings and operational values as minimum, normal and maximum flow, temperature and pressure
    • Composition of fluids

    Process flow diagrams generally do not include:

      • Pipe classes or piping line numbers
      • Process control instrumentation (sensors and final elements)
      • Minor bypass lines
      • Isolation and shutoff valves
      • Maintenance vents and drains
      • Relief and safety valves
      • Flanges

      Reference: Wikipedia

      Management/Process Safety Information and Knowledge/Process Design