Regarding the classification of dust explosion-proof areas
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“Classification of dust explosion hazard areas: Zone 20: Areas and inside containers where, during normal operation, combustible dust is present continuously or frequently in quantities sufficient to form a combustible dust-air mixture and/or may result in the formation of uncontrollable and extremely thick layers of dust. Zone 21: Areas where, during normal operation, there may be enough dust to form a flammable mixture with air, but which are not classified as Zone 20. This area includes: locations directly adjacent to the points where dust is introduced or discharged, as well as areas where dust layers exist and combustible dust-air mixtures that could reach flammable concentrations may be formed under normal operating conditions. Zone 22: Areas where, under abnormal conditions, combustible dusts appear occasionally and only for a short time, or where combustible dusts accumulate occasionally, or where dust layers may exist and thus form combustible dust-air mixtures. If it is not possible to ensure the elimination of accumulations or layers of combustible dust, it should be classified as Zone 21. ” So, how should instruments be selected for such an environment? ? I looked up a lot of information. Page P1091 of the third edition of the Design Manual for Automatic Control in Petrochemical Industries mentions only the concepts of dust explosion protection zones 10 and 11; it does not specify which instruments should be selected for these zones. \"Manual for Automated Design of Process Monitoring and Control in Steel Enterprises\", Page 232, Table 12-5. Page 335, Table 12-6: Selection of instrumentation for dust explosion protection in Zones 10, 11, 21, 22, and 23. In this manual, for the selection of instruments intended for dust explosion protection, IP54 to IP65 ratings are sufficient. For normal instrument selection, the protection rating should be at least IP65 for outdoor use and IP54 for indoor use. I’m a bit confused about it; I wonder if anyone has studied it in depth. Seeking answers
IP refers to the protection rating, while EX refers to the explosion-proof rating; the two should not be confused
Check GB50058-2014 – the main regulations regarding explosion protection can still be found in the electrical-related sections; so what’s the point of looking at the instrument manual?
It is necessary to refer to the electrical design codes for explosive environments, the latest standards from 2014
There are many posts on the forum regarding explosion protection ratings; you can search for them. Also, what was said on the second floor is correct – dust explosion protection should correspond to the EX classification
Dusts that can catch fire and explode, such as flour, are considered combustible dusts
Dusts that can catch fire and explode, such as flour, are considered combustible dusts