ATEX - MARKING

Zones, groups and categories
Devices for use in potentially explosive areas are divided into the following groups:
- GROUP I: devices used in mines
- GROUP II: devices used in surface installations
In the places and types of equipment covered by Directive 99/92/EC, the employer must carry out the classification of areas as to the danger of formation of explosive atmospheres in the presence of gas or dust.
The employer is the one who is the holder of an employment relationship with the worker and who is in charge of the company's (Direttiva 89/391/CEE [3])

Classification in zones according to Directive 99/92/CE:

ZONE	Explosive atmosphere	Mixture	Environment
0	Is present permanently or for long periods	Air + gas, vapour or mist	GAS
1	The formation is probable	Air + gas, vapour or mist
2	The formation is not probable	Air + gas, vapour or mist
20	Is present permanently or for long periods	Dust, powder could which is combustible in the air	DUST
21	The formation is probable	Dust, powder could which is combustible in the air
22	The formation is not probable	Dust, powder could which is combustible in the air

Correspondences between zones and categories according to Directive 94/9/EC
ZONE 0 / ZONE 20 => CATEGORY 1: equipment of this category guarantees the required level of safety even under rarely occurring equipment fault conditions. This equipment is used where an explosive atmosphere consisting of a mixture of air and gases, vapours or mist or of a dust/air mixture is present continuously or for long periods.
ZONE 1 / ZONE 21 => CATEGORY 2: equipment of this category guarantees the required level of safety even under frequently occurring equipment fault conditions. This equipment is used where an explosive atmosphere consisting of a mixture of air and gases, vapours or mist or of a dust/air mixture is present occasionally.
ZONE 2 / ZONE 22 => CATEGORY 3: equipment of this category provides the required level of safety under normal operating conditions. This equipment is used in areas where in all probability an explosive atmosphere consisting of a mixture of air and gases, vapours or mist or of a dust/air mixture will occur either not at all or only for a short time.

Protection type
"c": Protection through constructional safety (EN13463-5)

Temperature classes
Directive 94/9/EC, as most of the regulations relating to protection against explosions, identify the risk considering the nature of the dangerous product, and according to the ignition temperature of the product itself. Below is the table of the classes of maximum temperature of ignition for Group II: