Process Flow Diagrams (PFDs)
Standards, guidelines, and best practices for creating process flow diagrams.
Purpose of Process Flow Diagrams
The role of PFDs in process engineering documentation
A Process Flow Diagram (PFD) is a simplified schematic representation of a process system that shows the relationship between major equipment and the general flow of the process. PFDs serve as the foundation for more detailed engineering documents and provide a high-level overview of the process.
Primary Functions
- Communicate the general process flow and major equipment
- Show primary process streams and their flow directions
- Indicate major control loops that affect process operation
- Display key process parameters (temperature, pressure, flow rates)
- Serve as a basis for material and energy balances
- Provide a foundation for developing P&IDs
Scope Limitations
PFDs intentionally omit certain details that would be included in more detailed diagrams:
- Minor equipment (e.g., filters, small heat exchangers)
- Utility connections
- Detailed piping information (pipe sizes, materials, etc.)
- Most valves (except major control valves)
- Instrumentation details
- Electrical systems