The Directive on ATEX equipment 2014/34/EU (ATEX, atmosphères explosibles) applies to products intended for use in mixtures with air, under atmospheric conditions, of flammable substances in the form of gases or dusts. The Directive applies to both electrical and mechanical equipment; equipment assemblies; independent protection systems; safety, regulating and control equipment; and, in certain cases, individual components.
The Directive divides equipment into two groups based on where the equipment is used. Equipment in group I is intended for use in underground parts of mines and in those parts of surface installations of such mines where the explosion hazard is caused by firedamp and/or dust. Equipment intended for use in other potentially explosive atmospheres belongs to group II. Equipment in group I is divided into two equipment categories (M1 and M2), and equipment in group II into three different equipment categories (1, 2 and 3).
In addition to the safety level required of the equipment, the equipment category determines what kind of conformity assessment procedure must be applied before the product can be CE-marked and placed on the market in the EU. The identification number of a notified body will be appended to the CE marking, if the body is involved in the production control stage. In addition to the CE marking, a special explosion protection symbol and markings indicating the equipment group, equipment category and the intended operating environment shall be affixed to the equipment.
For more information on the ATEX Directive, see here.