Which explosion protection rating is the highest: IIA, IIB, or IIC?
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Which explosion protection rating is the highest: IIA, IIB, or IIC? Are devices of the corresponding higher grade more expensive? What grade is appropriate for the instrument junction boxes in the ammonia synthesis or methanol plant areas?
IIA Propane: 0.180 mJ IIB Ethylene: 0.060 mJ IIC Hydrogen: 0.019 mJ. It is recommended to search the forum; there are many posts available at http://bbs.hcbbs.com/viewthread.php?tid=337261&highlight=%B7%C0%B1%AC%B5%C8%BC%B6
IIC is high. For details, see GB50058
IIC is the highest. The ammonia synthesis plant should be IIC, and the methanol plant should be IIB.
China’s explosion protection rating standard is “GB3836.1-2000 Electrical equipment for use in explosive gas environments”; this standard is supplemented or modified by the following special standards for various explosion protection types. GB 3836.2 Electrical equipment for use in explosive gas environments – Part 2: Flameproof type “d” GB 3836.3 Electrical equipment for use in explosive gas environments – Part 3: Increased safety type “e” GB 3836.4 Electrical equipment for use in explosive gas environments – Part 4: Inherently safe type “i” GB 3836.5 Electrical equipment for use in explosive gas environments – Part 5: Positive pressure type “p” GB 3836.6 Electrical equipment for use in explosive gas environments – Part 6: Oil-immersed type “O” GB 3836.7 Electrical equipment for use in explosive gas environments – Part 7: Sand-filled type “q” GB 3836.9 Electrical equipment for use in explosive gas environments – Part 9: Encased type “m” GB 7957 Safety helmet lamps for use in mines. The above standards and this standard do not apply to medical electrical equipment, detonators, detonator testers, and ignition circuit testers. Common symbols include “ExdⅠ/Ⅱ BT3”. “Ex” is a general symbol meaning “explosive” (this is my personal interpretation); “d” indicates that the protection type is flameproof type “d”. “Ⅰ” or “Ⅱ” denotes the classification of the electrical equipment – Ⅰ refers to equipment used in coal mines, while Ⅱ refers to equipment used in other explosive gas environments besides coal mines. Among them, flameproof type “d” and inherently safe type “i” electrical equipment are further divided into categories ⅡA, ⅡB, and ⅡC. “T3” indicates the temperature group. For specific classifications and their meanings, please refer to “GB3836.1-2000 Electrical equipment for use in explosive gas environments”. ⅡA: Propane, 0.180 mJ; ⅡB: Ethylene, 0.060 mJ; ⅡC: Hydrogen, 0.019 mJ
IIC is the highest, IIA is the lowest