Differences in symbols on the PID diagrams of Shandong 3D Institute
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I would like to ask the experts: What is the specific difference between the upper limit settings for the on/off valves XZSO/XZSC and XZOI/XZCI in the sulfur recovery PID diagram of Shandong Sanwei Institute? Please explain in detail!
I understand: SO means chain open, SC means chain closed； OI is an indication (response) that the valve is fully open; OI is an indication (response) that the valve is fully closed.
XZSO--Valve position feedback on/XZSC---Valve position feedback off. These are mainly used to indicate status in tables showing digital inputs; DI points represent the digital signals that enter the control system. XZOI/XZCI indicate whether the valve is in the on or off state within the system, and can be considered as the names of the states displayed by the instruments on the computer – after all, some name is needed for them
Is the name different for each department?
I’m three-dimensional; is that strange? XZSO refers to the on-feedback switch at the site, while XZOI denotes the tag number for on-feedback in the DCS
It depends on the project; it doesn’t matter whether it’s X or Z. The numbering is custom-defined from the start, and that’s how it’s generally used
Isn’t the on/off feedback of the on-site valves all displayed on the DCS screen? Could you explain the meaning of your sentence in more detail?
It is fed back to the DCS, but it works on the same principle as PT and PI – in each system, there is a corresponding transmitter at the site
XZSO/XZSC are the instrument tag numbers for the open/closed limit positions of the on-site valves (ps: they are conceptually similar to PT and TT), while XZOI/XZCI refer to the virtual instrument tag numbers in the DCS system used for monitoring the feedback signals indicating whether the valve is fully open or fully closed (ps: they are conceptually similar to PI and TI). Do you understand this explanation?