Piping diagram chemical instrumentation symbols
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This post was last edited by qq_满满的808808 on September 3, 2018, at 10:37. The symbols used at various points in the process flow diagram: I’ve read HG/T 20505-2014, but there are still some parts I don’t understand. For instance, currently, instruments such as temperature sensors, pressure gauges, and valves are all installed on-site; the wiring leading to the DCS also has remote transmission capabilities, and the DCS controls them accordingly. Should I use on-site symbols to assign tag numbers, or should I use DCS-compatible symbols instead? Please, experts, explain this to me!
FT-101 is the instrument tag number, LV-101 is the valve tag number, and LIC-101 is the circuit number
I’m not quite sure where you want to write the tag number
What’s the purpose of writing a tag number? Establish instrument ledger? Debugging records? Circuit and alarm interlock system debugging?
What kind of diagram should I draw for PID process diagrams?
A process flow diagram needs to be drawn, including graphic representations and tag numbers
The tag number is assigned based on the variable being measured or that triggers a response; for example, TRCA-101 indicates temperature No. 101, which requires recording, control, and alarm functions. The tag numbers are not assigned based on the instruments or DCS installed on-site. Instruments or DCS (including virtual instruments or functions within the DCS) are distinguished by different graphic symbols.
This post was last edited by ylb913 on 2018-9-3 at 12:53. In fact, a control loop usually consists of multiple components both outdoors and indoors, such as on-site measurement elements, on-site transmitters, indoor controllers, and on-site electrical converters, among others. The number assigned to each component is called the instrument tag number; even the control valves themselves have such tag numbers. At the operational level, one should pay attention to the tag numbers of indoor instruments such as LIC, PIC, FIC, and TIC, while ignoring the tag numbers of instruments located outside. For example, sometimes when there’s a shift handover and it’s said that FIC101 is faulty, I need to ask whether it’s the control valve that’s problematic or if the flow display isn’t working properly
For example, for the thermocouple location TT1110 installed on-site, should I use ○ or something else to represent it?