Installation of safety barriers
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It is required that the field valve positioners be intrinsically safe, connected to the field PLC via the DCS; they are placed in the field PLC cabinet (with positive pressure ventilation), and from there connected to the DCS in the central control room. May I ask if safety barriers need to be installed both at the on-site PLC cabinet and the DCS? Do I need to set them all? Is it okay to set it on just one side? Is it okay to set them on both sides?
The on-site valve positioners are intrinsically safe; they are connected to the on-site PLC cabinet (with positive pressure ventilation), and from there, to the DCS in the central control room. Are the terminals in the PLC cabinet at the intervention site connected to the access cabinet? Is it still an IO card? If it is a terminal, an AO safety barrier can be installed in the DCS control room.
If a safety barrier is already installed in the PLC cabinet (with positive pressure ventilation), is it still necessary to install a safety barrier in the DCS cabinet in the central control room? @budaoweng123
It’s not necessary; an intrinsically safe circuit requires only one safety barrier.
Between DCS and PLC, a safety barrier is required; nothing else is necessary
It’s not necessary. If the PLC is equipped with a safety barrier, it’s the same as in the DCS room. The PLC cabinets in our factory are located in the same building as the DCS room, and the safety barriers are installed inside the PLC cabinets in that DCS room.
Um... what this means is that for intrinsically safe valve positioners, only one safety barrier is required between the field site and the control room; it can be installed in the field cabinet as well, or on the DCS side? Right? A newcomer asking for advice
It seems that the answers from above are not accurate! Please look up information online on intrinsically safe systems, explosion-proof designs, positive pressure explosion protection, and other related explosion prevention concepts! Explosion protection has strict requirements and certifications! The PLC cabinet on site only indicates positive pressure ventilation – is there any certification for that? What is the model of the cable on site! Is it intrinsically safe? What is the allowable cable length? It can’t be explained in just a word or two!