Instrument graphic symbols
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It has been bothering me for a long time; I would like to ask the experts here about the differences between the three symbols on this image. Photos from the actual site would be great, thank you. What is the difference between installation in a control room and installation on-site?
The legend symbols for LZ come from HG/T 20505 2000; this standard has since been updated to HG/T 20505 2014. The standard prior to 2000 was HG/T 20505 92; under the old standard, automation projects mainly involved conventional instruments. Conventional instruments are divided into field-mounted instruments (sensors, transmitters, control valves, etc.) and control room-mounted instruments (regulators, recorders, alarm indicators, calculation units, etc.). The installation of instruments in the control room is further divided into instruments installed on the dashboard surface and instruments installed behind the dashboard (such as arithmetic processing units and transmitters installed within the control room).
In simple terms, it is the difference between on-site installation within the control system and in the control room……
On-site installation, on-site dashboard installation, control room installation
On-site dashboards, control room dashboards: With the advancement of digitalization and the use of DCS systems, dashboards are being used less and less often. Moreover, due to factors such as safety, regulations allow retention only in certain special situations when it is necessary; as a result, the symbols cannot be removed.