Field-mounted instrument
A simple circle on a P&ID denoting a discrete instrument located in the field, accessible to the operator at the point of installation rather than mounted on a panel.
Read one of your own drawings.
Drop a P&ID, instrument index, or schedule. Tagsight reads it to the tag and opens a workspace you keep when you sign in.
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How it’s drawn.
A plain circle with nothing crossing it. The tag sits inside. The measured-variable and function letters on the upper half, for example FT, PT, LIC, the loop number on the lower half. The empty circle is the message. A solid horizontal line through the middle moves the instrument to the primary panel. A dashed line puts it behind the panel. A square, hexagon, or diamond around it hands the function to a shared display or logic solver. A field-mounted instrument sits out at the process, reachable by the operator who walks the unit.
Variants.
- Single circle, no horizontal line. Field mounted
- Circle with solid horizontal line. Panel mounted, primary location accessible to the operator
- Circle with dashed horizontal line. Behind-panel mounting, not directly accessible
Typical usage.
Used for the bulk of process instruments installed near the equipment they measure. Flow transmitters on a pipe run, level transmitters on a vessel nozzle, pressure gauges next to a pump. The mounting line conventions encode whether the instrument is field-accessible, panel-accessible, or hidden in the back of a marshalling cabinet.
Telling it apart.
- No line through the circle is the test. The instant a horizontal line crosses it, the instrument is panel or control-room mounted, not in the field.
- A square, hexagon, or diamond around the bubble is not a mounting variant. It signals a shared display, computer function, or logic solver.
- The letters name the loop by function, not the hardware. FT is a flow transmitter however the flow is sensed.
FAQ.
How do I know if an instrument is field or panel mounted from the symbol.
Look for the horizontal line through the circle. No line means field mounted. Solid line through the middle means primary panel mounted, operator-accessible. Dashed line means behind-panel mounted, auxiliary, not directly accessible.