Instrumentation symbols are essential elements in engineering drawings, particularly in the design and documentation of process control systems. These symbols are used on Piping and Instrumentation Diagrams (P&IDs), schematics, and installation diagrams to represent the control and measurement devices in the system. Understanding these symbols is crucial for anyone involved in the design, maintenance, or operation of a process control system.
Here’s a detailed look at the main categories and their uses:
1. Process Measurement Symbols
These symbols represent the various types of measurement devices used within the industry, such as temperature, pressure, flow, and level sensors. Common symbols include:
Flow Meter (F): Indicated by a circle with the letter “F.”
Temperature Sensor (T): Represented by a circle with the letter “T.”
Pressure Sensor (P): Shown as a circle with the letter “P.”
2. Process Actuators and Controllers
These are devices that control the operation of physical processes based on the feedback received from sensors.
Examples include: NO CONTENT
Control Valve (CV): Depicted with a generic valve symbol and often includes a letter to indicate its control function (e.g., “FC” for flow control).
Variable Speed Drive (VSD): Shown typically with a square and letters “VSD.”
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3. Lines and Connections
Different types of lines represent the connections between devices:
Solid Lines: Represent the process piping.
Dashed Lines: Often used for less permanent connections, such as electrical wiring or temporary links.
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4. Signal Identifiers
Symbols indicate the nature of the communication between devices, important for distinguishing between pneumatic, hydraulic, and electrical signals:
Dotted Line:
Often used for electrical signals.
Solid Line with Double Dashes: Represents hydraulic or pneumatic connections.
5. Miscellaneous Symbols
Include various other components such as:
Heater: Shown as a circle with waves inside
Fan/Blower: Represented by a simple fan-like symbol.
