ISA symbology
The International Society of Automation (ISA) is a non-profit professional association of engineers, technicians, and managers engaged in industrial automation. ISA is one of the leading standard organizations in the process control trade. They developed a set of symbols for use in the design of process control loops and other engineering diagrams. This set of symbols is referred to as ISA symbology and is detailed in one of their publications (ISA5.1, Instrumentation Symbols and Identification), which you can purchase at their website (https://www.isa.org/).
ISA symbology is used when creating Process (or Piping) and Instrumentation Diagrams (P&IDs).
A P&ID is a diagram that depicts the details of the piping and instruments used in a processing plant. Figure 12.14 shows a simple P&ID of a process control loop for a basic level of control. It is usually developed from a Process Flow Diagram (PFD) at the design stage of an industrial process plant. The...