A problem was found in HGT 20505-2014
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Will saying this in HGT20505 cause I to become unusable? What does it mean that it’s impossible to determine?
It says it’s the instruments displayed in the DCS, but sometimes it’s the local instruments.
The manual operator is a device that outputs signals; they cannot be confused.
“The basic meaning of “I” is “indication”; it can be an indication from a central control room, or it can be an on-site indication, such as digital displays on field instruments.
For example, how should it be indicated if a flow meter can display the readings both locally and in the control room?
A circle can be drawn, with no solid line in the center; FIT is indicated at the top (indicating flow measurement and signal transmission), while a number is indicated at the bottom***； Then, a dotted line (indicating a 4–20mA signal) is used to connect a circle with a box around it; inside the circle, thin solid lines show the flow rate indication on the DCS in the control room. “FI” is indicated at the top to denote the flow rate indication, while the same number *** is indicated at the bottom.
Can this dashed line be omitted, as I’ve seen some people not drawing it?
If the circle is tangent to the circled rectangle, the dashed line can be omitted. If it is inconvenient to place the drawing points and the two graphic symbols are separated, the dashed line cannot be omitted.