ATEX glossary

Equipped Ex d flameproof ATEX enclosures mounted on a frame

ATEX terms come up in every datasheet, every specification and every marking. Here are their definitions. The list follows the French alphabetical order of the original terms.

A to D

  • ATEX: short for the French “ATmosphères EXplosibles” (explosive atmospheres). Refers to the two European directives on explosion risks: 2014/34/EU for equipment and 1999/92/EC for worker protection.
  • Explosive atmosphere: mixture with air of combustible gases, vapours, mists or dusts, in which combustion can spread after ignition.
  • EU-type examination certificate: document issued by a notified body certifying that an equipment model complies with Directive 2014/34/EU.
  • Temperature class (T1 to T6): maximum surface temperature a piece of equipment can reach. T6 is 85 °C, the most severe. See gas groups and temperature classes.
  • EU declaration of conformity: document in which the manufacturer declares, under its sole responsibility, that its product complies with the directive.
  • DRPCE (explosion protection document): the French explosion protection document, mandatory for the operator of a hazardous site. See Explosion protection document and zoning.

E to H

ATEX junction box and control station, Antidéflagrant Service project (2026)
  • EPL (Equipment Protection Level): protection level of a piece of equipment: Ga, Gb, Gc for gases; Da, Db, Dc for dusts. Gb corresponds to zone 1 and is also suitable for zone 2.
  • Ex d (flameproof enclosure): type of protection in which the enclosure withstands an internal explosion and prevents it from spreading outside. See our Ex d enclosures.
  • Ex e (increased safety): type of protection that prevents arcs, sparks and excessive temperatures. See our Ex e enclosures.
  • Ex i (intrinsic safety): limiting the energy of circuits so that no spark can ignite the atmosphere.
  • Ex m, Ex o, Ex p, Ex q, Ex t: encapsulation, liquid immersion, pressurisation, powder filling, dust ignition protection by enclosure.
  • Group I / II / III: group I for mines susceptible to firedamp; group II for gases (IIA, IIB, IIC); group III for dusts (IIIA, IIIB, IIIC). Note: in ATEX marking, directive group II covers gases and dusts (II 2 G, II 2 D). Groups II and III above are those of the EN/IEC 60079 standards.
  • IIB+H2: group IIB extended to hydrogen, without covering acetylene or carbon disulphide. See our hydrogen enclosures.

I to O

  • IECEx: international certification system for Ex equipment, based on the IEC 60079 standards. See ATEX, IECEx and international certifications.
  • IP / IK rating: sealing against solids and liquids, impact resistance. See IP and IK ratings.
  • Flamepath: calibrated gap between two parts of an Ex d enclosure, which cools the gases from an internal explosion.
  • LEL / UEL: lower and upper explosive limits. Between the two, the mixture can explode.
  • ATEX marking: regulatory marking on the equipment: Ex hexagon, group, category, type of protection, gas group, temperature class. See ATEX marking.
  • Notified body: body authorised by a member state to assess the conformity of ATEX equipment, for example INERIS or LCIE in France.

P to Z

  • Cable gland: cable entry device that maintains the enclosure’s type of protection. See choosing an ATEX cable gland.
  • QAN / QAR: production quality assurance notification (ATEX) and quality assessment report (IECEx), which certify that production is under control.
  • Auto-ignition temperature: minimum temperature at which a gas ignites spontaneously on contact with a hot surface.
  • Zone 0, 1, 2: gas zones, according to how often an explosive atmosphere is present. Zone 20, 21, 22: their equivalents for dusts. See ATEX zones.

A term is missing, or you have a question about your installation? Our design office will answer.

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