6 Essential Instrumentation Documents and Diagrams used By Instrumentation Engineers

Instrumentation Engineering Documents and Diagrams

In the process industry, the instrumentation is so broad and which includes most of the sections in an industry, so no one form of diagram is sufficient to capture all we might need to represent.

There are different types of diagram and documents used by instrumentation engineers:

Process flow diagram:

The device engineer/technician at the greatest stage is involved in process vessel interconnections, tubes, and process fluid stream routes.

A system stream diagram is called the appropriate diagram shape to portray a process’s large image. Individual instruments are sparsely represented in a PFD as the process itself is the focus of the diagram.

Loop diagram:

The device engineer/technician is concerned in the interconnections of individual tools at the smallest stage, including all wire numbers, terminal numbers, cable kinds, calibration ranges of tools, etc.

For this stage of good detail, the correct diagram shape is called a loop diagram. The process ships and piping are depicted scarcely here because the diagram’s focus is on the tools themselves.

Piping & Instrumentation Diagram (P&ID:

Piping and equipment diagrams (P&IDs) are between system stream diagrams and circuit diagram somewhere in the center.


A P&ID is a streamlined drawing illustrating the machinery used in a process along with its interconnections (piping rows) with the tools and control systems that indicate the system’s process flow. These diagrams are original sketches on which GUI big control system software such as SCADA and DCS is based.

Functional Diagram:

For a completely distinct intent, functional diagrams are used: to document a control system’s approach.

In a functional diagram, in contrast to piping, wiring, or device relations, emphasis is put on the algorithms used to regulate a system. These diagrams are frequently discovered in the energy generation sector, but sometimes they are also used in other sectors.

Hoop-up drawing:

Hook-up sketch offers a comprehensive overview of the device set up in the right manner, from the point of touching in the process row to the detecting tool.

The hook-up chart shows the paths of the tube, the location of the tool in relation to the stage where the method is tapped, the breakage of the grip between the tool and the pipe.

Instrumentation Index:

Instrument index is a paper produced at the start of the project, containing the list of tools used in the factory. The label number, label number, P&ID number, loop number, service number, etc. is the name of the tools.


Check the device index for information such as the place of the executed tool (area), in which P&ID, hook-up diagram and loop diagram belong to the tool, and the details of the production, etc.