Weidmueller Enclosures & Cable Glands

Directive 1999/92/EC
Technical appendix
Directive 1999/92/EC
Article 137 of the European Community Formation Treaty
set out the minimum standards in order to improve workers’
health and safety, this can also be put at risk by explosive
atmospheres. An explosive atmosphere is a mixture of
air and flammable gasses, vapours, mists or dust under
atmospheric conditions where, following successful ignition,
the burning process will propagate throughout the whole
unburned mixture.
The directive 1999/92/EC was transferred into national law.
Compliance with the minimum standards contained in this
directive does not guarantee that all relevant national laws
are met. It is possible for local regulators to introduce more
stringent requirements.
The employer is required, according to the directive
1999/92/EC, to take measures to ensure the health and
safety of the employees. One measure is the division of
the area into zones where explosive atmospheres could be
present.
Unless the risk analysis conducted by the employer indicates
otherwise, all areas where an explosive atmosphere may
be present must be equipped with devices and protective
systems that meet the relevant category of the ATEX
directive 2014/34/EU.
In particular in these zones the following categories of
equipment should be used, as long as they are suitable for
use with gases, vapours, mists or dusts:
• In Zone 0 or Zone 20: category 1 devices,
• In Zone 1 or Zone 21: category 1 or category 2 devices,
• In Zone 2 or Zone 22: category 1, category 2 or
category 3 devices.
Zoning according to the directive 1999/92/EC
Explosion risk areas are classified into zones according to
likelihood of explosive atmospheres occurring and their
persistence.
Zone 0
An area which has a potentially explosive atmosphere that is
a mixture of air and flammable gases, vapours or mists.
The mixture is either permanently present or frequently
present over long periods of time.
Zone 1
An area in which during normal operations a potentially
explosive atmosphere of air and flammable gases,
vapours or mists can occasionally form.
Zone 2
An area for which during normal operations there is at
most only a short-term occurrence of a potentially explosive
atmosphere of mixtures of air and flammables gases,
vapours or mists.
Zone 20
An area where a potentially explosive atmosphere is present
in the form of a flammable dust cloud in the air. This cloud
is either permanently present or frequently present over long
periods of time.
Zone 21
An area where, during normal operations, a potentially
explosive atmosphere in the form of a flammable dust
cloud in the air can occasionally form.
Zone 22
An area where, during normal operations, a potentially
explosive atmosphere in the form of a flammable dust
cloud in the air is not normally present or only present for a
short time.
W
For the risk assessment and as well as the zoning concept
described above, Ex devices themselves can be considered
in an alternative process which uses the equipment
protection level (EPL). These protective levels determine the
internal ignition risk of a device where the sort of applied
protection does not play a role.
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