Introduction to graphic symbols of instrument functions

first question: The first graphic in the first row and the fourth symbol in the first row are displayed without specifying them. Graphical symbols indicate the properties and functions of the component. The first figure in the first row indicates that this is a component in a basic process control system (not specifically indicating the function). The triggering parameters (first letter) and function (subsequent letters) of the component are given by the letter string. There is no line between these two graphic symbols, indicating that they are implemented on site. The first one is a component of the basic process control system, and the fourth one is a conventional instrument (that is, a physical instrument). For example, in a basic control system, if you choose a pressure transmitter with a control function (fieldbus system transmitter), you need to mark it as PCT in the drawing. If you choose a pressure control valve with a control function (a control valve with a fieldbus valve positioner), you need to mark it as PCV in the drawing. ； If a pressure gauge is selected for pressure indication, the fourth graphic symbol is used, and PI needs to be marked in the graphic. If a conventional pressure transmitter is selected, PT needs to be marked in the graphic. second question: The double thin solid lines in the figure indicate that the function (or instrument) is implemented (or installed) in the on-site control room (field cell) rather than in the central control room. For example, most of the online analyzers at the production site are installed in the on-site analyzer cabin, where there may also be control, calculation, recording, and indication functions.

Thank you very much for such a detailed explanation. It is very useful. Thank you again.

To simply understand, one is charged, one is not charged, one has a tray and rack, and one does not.