Каталог Weidmuller: Electronics - Analogue Signal Conditioning

Glossary
Technical appendix/Glossary
Z
Zone division
Hazardous areas are divided into zones. These divisions take into account the
various risks from explosive atmospheres. The corresponding explosion protection
can then be implemented economically and safely in accordance with the
particular conditions of the zone. The zone definitions in the ATEX directive provide
comprehensive regulations for the European Community.
IEC 60079-10 is valid for gases and vapours. A similar classification is used for
facilities in the USA which are covered by the US standard NEC 505.
IEC 61241-3 covers the division into zones according to the dust level.
Explosion risk areas are classified into zones according to likelihood of explosive
atmospheres occurring and their persistence:
Zone 0: this zone has an explosive atmosphere that is a mixture of air and
flammable gases, vapours or mists. The mixture is present frequently or
over long periods.
Zone 1: an explosive atmosphere may occasionally occur in this zone under normal
operating conditions.
Zone 2: an explosive atmosphere is not likely to occur in this zone or may only
occur briefly.
Zone 20: this zone has an explosive atmosphere that is a flammable mixture of air
and dust. The mixture is present often or over long periods.
Zone 21: an explosive atmosphere, in the form of a flammable dust/air mixture, may
occasionally occur in this zone under normal operating conditions.
Zone 22: an explosive atmosphere, in the form of a flammable dust/air mixture, is
not likely to occur in this zone or may only occur briefly.
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