Honeywell RMA 3000, User Manual

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Release 1 34-ST-25-19 RMA 3000 Remote Meter Assemblies User Manual 39
6/04
About IEC
The IEC has established a number of recommendations applying to the construction
of explosion protected electrical apparatus identified. These recommendations are
found within IEC 79-0 through
79-15 and 79-28.
For all EC countries as well as various neighboring countries (CENELEC member
states), the European Standards EN 50 014 to EN 50 020 and EN 50 039 apply for the
construction of explosion protected electrical apparatus. They were established on the
basis of the IEC. However these recommendations are much more detailed by
comparison.
Zones
Hazardous locations, within IEC7-10, are classified into one of these three zones.
ZONE Description of Hazardous Location
0 Explosive gas atmosphere is present continuously, or is present for
long periods.
1 Explosive gas atmosphere is likely to occur in normal operation.
2 Explosive gas atmosphere is not likely to occur in normal operation
and, if it does occur, it will exist for a short period only.
IEC Groups
Flammable gases, vapors and mists are further classified into groups according to the
energy required to ignite the most easily-ignitable mixture within air. Apparatus is
grouped according to the atmospheres it may be used within as follows:
Group Description of Atmosphere
IIC Atmospheres containing acetylene, hydrogen, fuel and combustible
process gases or vapors of equivalent hazard.
IIB Atmospheres such as ethyl ether, ethylene, or gasses or vapors of
equivalent hazard.
IIA Atmospheres such as acetone, benzene, butane, cyclopropane,
ethanol, gasoline, hexane, methanol, methane, natural gas, naphtha,
propane or gases or vapors of equivalent hazard.