Hazardous zones Instrumentation

[maintennance]

For selecting Instruments for a dusty atmosphere ( coke drum area),the hazardous area classification says it is zone 22 where as the vendor supplying the instruments to suit Zone 2. Vendor claims that Zone 2 ( fit for gases) is sufficient enough for this. Thanks to clarify,the statement by the vendor.Also would like to know the difference between these two plesae

 

[zappedagain]

While I haven't worked in dust environments, it make sense that gas (zone 2) would have stricter requirements than dust (zone 22). Explosive gases vs combustible dusts/ignitable fibers is the environmental difference between the two zones, respectively.

Zone 22 is defined in NFPA 70 Article 506 (of which I don't have a copy). You might check there or try searching or posting on this forum:

http://www.eng-tips.com/threadminder.cfm?pid=184

John D

 

[ScottyUK]

If you're working under the ATEX directive then there are two distinct classifications. When asking code questions it makes things so much easier if you state where you are and what code you are governed by.


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