P&ID General Instrument Symbols
- Horizontal lines, which run through the symbols and divide them in half, or an absence of lines indicates:
- How the instrument is mounted
- Where it is located
- Symbols without horizontal lines indicate the instrument is installed in the field, either:
- At the point measurement
- Near the final control element
- Symbols with a single line indicate the instrument is mounted on a panel board in the control room, making it accessible to the operator or for routine maintenance.
