B.2 | International Electrotechnical Commission (IEC) | |||||
| Classification of Hazardous Locations | |||||
About IEC |
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| The IEC has established a number of recommendations applying to the | ||||
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| construction of explosion protected electrical apparatus identified. | |||
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| These recommendations are found within IEC | |||
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| For all EC countries as well as various neighboring countries | |||
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| (CENELEC member states), the European Standards EN 50 014 to EN | |||
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| 50 020 and EN 50 039 apply for the construction of explosion protected | |||
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| electrical apparatus. They were established on the basis of the IEC. | |||
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| However these recommendations are much more detailed by | |||
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| comparsion. |
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Zones |
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| Hazardous locations, within | ||||
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| three zones. |
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| ZONE |
| Description of Hazardous Location |
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| 0 |
| Explosive gas atmosphere is present continuously, or is |
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| present for long periods. |
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| 1 |
| Explosive gas atmosphere is likely to occur in normal operation. |
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| 2 |
| Explosive gas atmosphere is not likely to occur in normal |
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| operation and, if it does occur, it will exist for a short period |
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| only. |
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IEC Groups |
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| Flammable gases, vapors and mists are further classified into groups | ||||
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| according to the energy required to ignite the most | |||
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| mixture within air. Apparatus is grouped according to the atmospheres | |||
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| it may be used within as follows: | |||
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| Group |
| Description of Atmosphere |
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| IIC |
| Atmospheres containing acetylene, hydrogen, fuel and |
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| combustible process gases or vapors of equivalent hazard. |
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| IIB |
| Atmospheres such as ethyl ether, ethylene, or gasses or |
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| vapors of equivalent hazard. |
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| IIA |
| Atmospheres such as acetone, benzene, butane, |
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| cyclopropane, ethanol, gasoline, hexane, methanol, methane, |
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| natural gas, naphtha, propane or gases or vapors of |
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| equivalent hazard. |
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| Continued on next page | |
2/05 | ST 3000 Release 300 Installation Guide | 89 |