Ex switchgearGlossary

Z

Zone division: The division of the gas-Ex zones mustbe carried out according to EN 60079-10 and the divisi- on of dust-Ex zones according to EN 50281-3. If there are special applications or doubts about the classificati- on of explosive endangered areas, the authorities deci- de (Trade Supervisory Office, if necessary in cooperati- on with the Employees’ Liability Insurance Association orthe TÜV ). Zone 0: comprises areas where an explosive atmos-phere is present permanently or over a long time. That is inside of industrial containers or apparatus (steamers, reaction tube), when the conditions defining zone 0 are met. Zone 1: comprises areas where an explosive atmos-phere is present sometimes. That is in the closer vicinity of zone 0, of feeding entries, around filling and emptying units, as well as around fragile apparatus or pipes made of glass, industrial ceramics and around insufficiently insulated industrial plugs on pumps and gate valves, etc. Zone 2: comprises areas where an explosive atmos-phere is rarely present and then only for a short time. These are areas surrounding zone 0 or 1 or around Flanschconnectors with standard type flat sealings in closed rooms. Rooms where flammable materials are only transported inside pipes with welded or hard-sol- dered connections are not explosive endangered areas. Zone 20: comprises areas where an explosive atmos-phere is present often or over a long time. That is inside containers or apparatus (mills, professional dryers, professional mixers, pipes, professional silos etc.), when dust can form explosive mixtures in a dangerous quantity, often or over a long period of time. Zone 22: comprises areas where during normal ope-ration an explosive atmosphere in the form of a cloud containing the flammable dust of the air is present not at all or only sometimes for a short time. Zone 21: comprises areas where an explosive atmos-phere is sometimes present for short time because of a raising of settled dust. That is in the vicinity of dust-con- taining apparatus, where dust leaks and collects in en- dangering quantities (e.g. mill rooms where dust can escape and deposit). This glossary explains some basic terms which are used in the catalogue but is by no means complete. Suggestions for additions are welcome.

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