ATEX
How it works
ATEX classifies equipment into two groups: Group I (equipment for underground mines and surface installations endangered by firedamp/coal dust) and Group II (equipment for other places with explosive atmospheres). Group I has categories M1 and M2, while Group II has categories 1, 2 and 3, with a G suffix (gases, vapours, mists) or D suffix (dusts), corresponding to the required protection level. The workplace directive (1999/92/EC) divides spaces into zones by the likelihood of an explosive atmosphere: Zones 0, 1, 2 for gases and Zones 20, 21, 22 for dusts. The equipment category must match the zone (Cat 1 → Zone 0/20, Cat 2 → Zone 1/21, Cat 3 → Zone 2/22). Conformity with the essential requirements is usually achieved by applying harmonised technical standards from the EN/IEC 60079 series (protection types include Ex d — flameproof enclosure, Ex e — increased safety, Ex i — intrinsic safety, Ex p — pressurization). The manufacturer performs the conformity assessment (with a Notified Body for higher categories), issues an EU declaration of conformity, and affixes the CE marking and the Ex marking (the hexagonal Ex symbol with the group and category).
Problem solved
Before ATEX, each EU Member State applied its own rules for equipment destined for explosive-atmosphere zones, hampering free movement of goods and creating inconsistent safety levels. ATEX resolves this by defining common essential requirements, a classification of zones and equipment categories, and a single conformity-assessment and marking procedure across the internal market.
Components
A recast of Directive 94/9/EC; harmonises requirements for equipment and protective systems for explosive atmospheres; applicable since 20 April 2016.
The "ATEX 137" directive; minimum requirements for protecting workers at risk from explosive atmospheres, including zone classification.
Group I (mining: M1, M2) and Group II (other: 1, 2, 3) with a G (gas) or D (dust) suffix, defining the equipment's protection level.
Classification of spaces by the likelihood of an explosive atmosphere: gases — Zones 0/1/2, dusts — Zones 20/21/22; matched to the equipment category.
Conformity-assessment procedures (often with a Notified Body), an EU declaration of conformity, and affixing the CE marking and the hexagonal Ex symbol.
Implementation
Selecting equipment of a lower category than the zone requires (e.g. Cat 3 in Zone 1) breaches the requirements and creates a real ignition risk.
ATEX (mandatory EU law with CE marking) is sometimes treated as identical to IECEx (a voluntary international scheme); an IECEx certificate alone does not replace ATEX conformity for the EU market.
Evolution
The original ATEX equipment directive, establishing common requirements for equipment for explosive atmospheres.
The workplace directive: minimum requirements for worker protection and hazard-zone classification.
From 1 July 2003, Directive 94/9/EC became mandatory for equipment placed on the EU market.
The recast equipment directive was adopted (26 February 2014), aligned with the EU New Legislative Framework.
From 20 April 2016, Directive 2014/34/EU replaced Directive 94/9/EC as the governing law.