Wiring issues for instruments in explosion-proof areas
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This post was last edited by dennyshen2549 on 2022-5-4 at 10:21. Recently, companies are conducting safety audits, and the wiring of instruments in explosion-proof areas needs to be modified; in principle, the safety level should not exceed SIL1. That’s my plan: I intend to use EX-rated explosion-proof instruments, and EX-rated explosion-proof flanges for the electrical connections. The outlet of the wire conduit does not use an explosion-proof flexible tube – instead, a small section is left exposed before it enters the instrument flange. Is this connection method compliant with the requirements?
Using a glanded connector for the power connection can meet the requirements of Appendix A and Figure 3 in GB 3836.1-2010 \"Explosive atmospheres – Part 1: General requirements for equipment\". I’m explaining this in such detail because the use of Gran head connectors was only included in the explosion-proof regulations in 2010; to this day, some design institutes’ design manuals still do not recognize such connectors. You need to prevent running into stubborn people ； When choosing a gland head, it’s best to look for ones with an explosion-proof mark; although there isn’t much difference in performance, it helps you meet inspection requirements. .
Mm. . . To be honest, EX merely indicates explosion protection; it does not specify the type of explosion protection. You need to determine the appropriate connection type based on the specific type of explosion protection being used. For example, intrinsically safe systems can use waterproof sealed connectors, while flameproof systems require flameproof sealed connectors. As for what you mentioned about using a gland head with a small section of cable exposed, this is in compliance with the standards; for more details, refer to the Chemical Instrumentation Installation Manual HGT21581, specifically the section on the connection of instrument cable protection tubes.
Yes, the level here will not exceed SIL1, so an EXd explosion-proof type is used
The SIL rating has nothing to do with the explosion protection rating; they belong to two completely different areas.
An explosion-proof gland can be used, but it’s best to protect the part that leads to the conduit with a bellows. HGT20512-2014 describes this method; you can take a look.