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atmospheres: important
information
What is ATEX?
● It is a term commonly used to describe potentially EXplosive ATmospheres and
standards for protection systems and equipment.
● Two European directives, ATEX 99/92/CE and ATEX 94/9/CE, and international
standards IEC 60079 and IEC 61241, harmonized with EN European standards,
apply to this field.
How is a potentially explosive atmosphere defined
according to ATEX?
● An potentially explosive atmosphere is defined as a mix of flammable substances
in the form of gas, vapour, dust (cloud or deposit) which, in air and under normal
atmospheric conditions, can completely or partially catch fire in the form of an
explosion when exposed to a source of ignition.
Classification of an explosive atmosphere
● They are classified into groups and zones according to directive 99/92/CE and
IEC standards as follows:
Destination
Categories/presence of
potentially explosive
atmosphere
Hazardous zones
Atmosphere
Group I
Mines
M1 and M2
Gas and dust (G & D)
Group II
surface
Industries
1
Permanent or frequent
Zone 0:
gas and vapour
G
Zone 20:
mist and dust
D
2
Occasional
Zone 1:
gas and vapour
G
Zone 21:
mist and dust
D
3
Rare
Zone 2:
gas and vapour
G
Zone 22:
mist and dust
D
Zone 0
Zone 2
Zone 1
Zone 20
Zone 22
Zone 21
Product directive
94/9/CE: defines
the manufacturers'
obligations.
Personal protection
directive 99/92/CE:
defines the users'
obligations.
Heat
Fuel
Oxygen
Chain
reaction
Explosive atmosphere
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