Piping and instrumentation diagram
Piping and instrumentation diagram
Embedded Files
Symbols
Symbols
[2]
Balloon symbols
Balloon symbols
Balloon symbols or instrument bubles are circular P&IDs symbols representing a system's instruments or control functions.
[2] A circle symbol is comprised of 3 characters:
The first top letter indicates the parameters being controlled. E.g., flow = 'F', temperature = 'T', level/pressure = 'L', etc
The second top letter indicates the type of control device used. E.g., transmitter = 'T', valve = 'V', etc.
The bottom number indicates the loop (tag) number, i.e., the control circuit the device is part of. It's called a loop number as circuits are physically/conceptually closed feedback loops where devices (sensors, controllers, controllers) reads and sent a data in loops.
The line or the absence of a line indicates the device's location.
[3]
Valve symbols
Valve symbols
A valve is a mechanical device used to start/stop/regulate liquid/gas flow in a pipe, with its standard symbol represented as two triangles facing each other
Pipe lines
Pipe lines
[3]
Piping (Solid bold lines) (basically normal lines) represent main physical pipes through which substance flow through.
Connection to process (thing lines) represent small/narrow static pressure pipes.
Undefined signals (single slashing lines) represent compressed air signals
Pneumatic signals (double slashing lines)
Electric signals (dashed lines) represent electric signals carrying measurement data/control commands (often 4-20 mA DC).
Hydraulic signals (L lines) represent pressurized liquid (often hydraulic oil/water) used to transmit power/control signals to actuate machineries.
Capillary tubes (lines with 'X's) represent sealed tubes with fluids
capillary tube: narrow thin pipe with liquid flowing
capillary (engineering): liquid's ability to flow through narrow thin space
Electromagnetic/Sonic signals represent
Internal system links (lines with empty circles) represent
Internal system links (lines with black circles) represent
Examples
Examples
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