On the explosion protection issues of intrinsically safe circuits
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When the field devices are intrinsically safe, the connection cables are intrinsically safe cables, which are connected to the safety barrier inside the control cabinet. May I ask: 1. Are explosion-proof flexible pipes required for the cable conduits of on-site instruments and the instruments themselves? 2. Is it necessary to seal the conduit that runs from the site into the cable tray with an explosion-proof seal? 3. How should the power supply for the safety barrier in the control cabinet be selected? Are other safety measures required to form an intrinsically safe circuit? I would appreciate it if experts could advise on how to resolve this issue, and specifically which security regulation governs it.
Based on my experience and understanding: 1. Whether it is an intrinsically safe instrument or a flameproof instrument, an explosion-proof flexible tube is not necessary, as the instrument’s connection threads already provide the necessary sealing； 2. There is no need to apply explosion-proof sealing to the conduit running from the site into the cable tray; the purpose of the conduit is to protect the cables and facilitate their installation, and it does not serve any explosion-proof function ； 3. An intrinsically safe power supply should be used.
With a safety barrier in place, a high-quality power supply will do; there’s no need to consider this regulated power supply anymore
1. Not required. 2. On-site, when conduits need to be led into the cable tray, those conduits must be sealed in an explosion-proof manner to prevent explosive substances from entering the cable tray and the conduits. 3. An intrinsically safe power supply should be used. It must match the signal