Without one of these three elements we cannot speak of a potentially explosive atmosphere and, consequently, we do not fall under the scope of application of ATEX directive.
The second aspect, as we already explained in the article “General content of 94/9/EC European Directive“, is a matter of classification. In fact work areas are classified into zones according to frequency and duration of explosion risk in atmosphere due to gas presence (in this case we talk about atex zones 0, 1 or 2) or to dust (so talking about atex zones 20, 21 or 22).
Let’s focus on explosive dusts now: talking about dust, we will take into consideration following classified areas:
- Zone 20 = an atmosphere where a cloud of combustible dust is present frequently, continuously or for long periods;
- Zone 21 = area in which the formation of an explosive atmosphere is occasional;
- Zone 22 = area in which the formation of an explosive atmosphere is not probable and, if it occurs, it would be of short duration;
Systems positioned in zone 20 or 21, due to greater risk of explosion, must be certified by special Bodies and must be equipped with double safety systems with consequent increase in construction costs.
For this reason, it is recommended to place the abatement system outside the production area (usually zone 22). In the latter case the plant must be equipped with a single safety system and self-certification is sufficient to certify its compliance with the ATEX directive.