Chapter 01 - Instrumentation Control Systems Documentation by Frederick A. and Clifford A. Meier. An ISA Publication.

1. Process Flow Diagrams
(PFD’s)
Chapter 01 – The Process Flow Diagram
EMEC125

2. What is a PFD and Who Uses Them?
• What is a PFD?
• Process Flow Diagrams (PFD’s) are drawings that show a representation of
only the absolute required elements of the entire process. They are a
schematic representation for converting raw materials into a finished product.
The details of this conversion are not shown on PFD’s.
• Who uses them?
• Strategic planners
• Managers at the corporate level
• Designers
• Sometimes, regulatory agencies

3. Minimum Amount of Detail on a PFD
• Process critical details are schematically shown in the least amount of
space
• PFD’s are the “Big Picture”
• Line sizing is rarely, if ever shown
• Only show equipment that:
• Impacts material balance
• Has a large impact on utilities
• Contains an ownership transfer point
• Process equipment that is needed for further definition of the process
• Special equipment

4. Additional Detail on a PFD
• Details may be added at the customer request if implementation is
complex and/or costly to the project
• Major measurement points, some control valves and control methods
and possibly process analyzers can be shown. These types of items
will then be duplicated on the P&ID
• When the PFD is reviewed, there should be:
• Enough information to help with the development of all the P&ID’s
• Long lead items should be spelled out

5. PFD Example – Basic Cement Plant
PFD_Cement_Plant.pdf

6. Process Description for Cement Plant
• Lime stone is mined at the local quarry and crushed with a bell crusher and
hammer mill.
• The crushed lime stone is conveyed to a stone storage/blending building
where a bridge crane blends it with Gypsum, Silica, Sand and Clay
depending on the grade of cement being produced.
• The blend of materials are then conveyed to a ball mill where it is
pulverized.
• The pulverized material is then dried and blown into a rotary kiln that
burns the material at 1,450°C/2,642°F.
• The result of burning the material creates clinker with is place into a
storage silo.
• The clinker is than placed in a finishing ball mill to produce the powder.
• The cement is conveyed to a finished goods silo where it can be packed in
bags or bulk loaded into tank trucks.

7. Classroom Exercise
• Pick a process that you are familiar with and hand draw/sketch the
process.
• We will then discuss some of them as a group.