What is ATEX?

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Chances are that you have seen an ATEX rating, zone classification, or an EX rated logo on a piece of equipment. But what does this indicate about the product? This article will discuss everything you need to know about the definition of ATEX, approved products, certification, and more related subjects.

What is ATEX?

The term “ATEX” is derived from the French words “Atmospheres Explosibles” and refers to European directives for controlling explosive atmospheres. These directives cover the minimum safety requirements for improving the health and safety of workers and the equipment and protective systems intended for use in these atmospheres. In other words, these directives are designed to protect employees from explosion risks in explosive atmospheres. The ATEX directives are widely recognized and implemented, and industry professionals and companies across the European Union follow the guidelines.

Explosive atmospheres

Explosive atmospheres are defined as atmospheres containing a mixture of air and combustible substances under atmospheric conditions, in which the combustion can spread to the unburned mixture after ignition.

To clarify this definition a little bit: combustible substances include gases, vapors, mist, or dust. Subsequently, atmospheric conditions are defined as ambient temperatures and pressures. In other words, temperatures between -20 and 40 degrees celsius and pressures of 0.8 to 1.1 bar.

These atmospheres are present in many settings, such as:

  • Oil and gas production facilities
  • Chemical and pharmaceutical manufacturing plants
  • Food and beverage manufacturing facilities

And other workplaces that contain, handle, or produce activities releasing flammable gases, vapors, or fine dust. In addition, leaks, spills, and over-pressurization can also create explosive atmospheres.

These atmospheres can pose a significant risk to workers because they have the potential to ignite and cause explosions. Therefore, following the guidelines concerning the corresponding atmosphere is crucial to minimize explosion risks and ensure safety. A common way of minimizing risk is the removal of potential ignition sources because the goal is to prevent contact between these atmospheres and ignition sources. This is often done by using ATEX equipment.

Employers are required to classify explosive atmospheres into different zones. In Europe, these zones are called ATEX zones. The size, location, and classification of these zones depend on the likelihood of occurrence and persistence of these atmospheres. Furthermore, the zones determine requirements such as the certification of the equipment used within that zone. This brings us to the next question; What are ATEX zones?

ATEX Zones explained

Now that we have learned more about the definition, let’s dive deeper into the different ATEX zones and their classification. The zones are divided into two types of hazardous areas based on the fuel that may be present in the air (gas or dust). Secondly, the hazardous areas are subdivided into different zones or categories.

ATEX zones for gases and vapors

  • Zone 0 / Category 1G
  • Zone 1 / Category 2G
  • Zone 2 / Category 3G

ATEX zones for dust

  • Zone 20 / Category 1D
  • Zone 21 / Category 2D
  • Zone 22 / Category 3D

The classification of ATEX zones depends on the presence of explosive mixtures in the area. For example: “Zone 0 ATEX” means a continuous presence of explosive mixtures in the area. Equipment for zone 0 should still be working safely after two separate malfunctions. This also applies to Zone 20. Next, zone 1 (and zone 21) means that explosive mixtures are likely to occur during regular operation. The equipment should still be working safely with one separate malfunction. Lastly, zone 2 (and zone 22) classification means that explosive mixtures are not likely to occur during regular operation; if they will, they will be for a short time.

Logically, the zone classification determines how strict the standards are to be met, leading us to the question: what are ATEX standards?

ATEX Standards

For every different zone, there are different standards. These standards are compiled by the ATEX directive for controlling explosive atmospheres and may be used as an aid for developing products. However, there is room for interpretation, and deviation from these standards is possible.

For example, equipment appropriate for use in zone 0 has to meet standards different from the equipment intended for use in zone 2. Therefore, it is crucial that the ATEX zones in your working environment are correctly identified and classified. Afterward, appropriate equipment shall be installed.

ATEX Directives

The directives cover the mandatory regulations concerning equipment and protective systems for use in explosive atmospheres. They also define conformity assessment procedures and safety and health requirements. National authorities are responsible for implementing and enforcing the directives. Companies that deal with explosive atmospheres must comply with the corresponding ATEX directives. The two different directives are:

  • ATEX 114 (ATEX 2014/34/EU): describes the minimum safety requirements of equipment for manufacturers.
  • ATEX 153 (ATEX 1992/92/EG): describes the minimum safety requirements for a safe working environment intended for employers.

If you want to check whether a product conforms to specific standards or is Ex rated, you want to keep an eye on the “Ex” rating displayed on the right. Within the European Union, ATEX equipment must also be CE certified.

Product Marking


All certified products come with a marking, also called an ATEX rating label. For example, the label is displayed below.

From this picture, we can conclude that the product is certified for use in Zone 1 (category 2G). The notified body has certified this product and is listed under “0085.” To clarify all the other markings and symbols on the label, we have made a table with the most common markings.

Explosion proofThe product is ATEX certified.
Equipment GroupIFor use in underground mines.
IIFor use in all other places.
Category1 (Zone 0/20)An explosive atmosphere is continuously present.
2 (Zone 1/21)An explosive atmosphere is likely during normal operation.
3 (Zone 2/22)An explosive atmosphere is unlikely during normal operation.
EnvironmentG (Zone 0/1/2)Equipment is certified for use in environments with flammable gases.
D (Zone 20/21/22)Equipment is certified for use in environments with dust.
Temperature classT1Maximum surface temperature of 450ºC
T2Maximum surface temperature of 300ºC
T3Maximum surface temperature of 200ºC
T4Maximum surface temperature of 135ºC
T5Maximum surface temperature of 100ºC
T6Maximum surface temperature of 80ºC

Please be aware that this table does not cover every marking on ATEX products, for example, the protection methods. You should always consult an expert before (first-time) using, maintaining, or repairing any item in a potentially hazardous area.

ATEX Certification

Equipment must feature a certification before it is allowed to be used in specific zones.

Certification must be supplied with any ATEX equipment. To receive a certification for a piece of equipment, the equipment has to be tested by a third party in most cases. These third parties are called notified bodies. Certified products improve the safety of working environments and reduce the risk of potential explosions in hazardous areas. Lastly, it is essential to know which zones are dealt with in the working environment to determine which equipment may be used because equipment for zone 1 does not guarantee safety in zone 0. You can find the different zones of the working environment in the explosion protection document. ATEX 153 requires employers to construct this document.

Cheat sheet [ATEX glossary]

  • ATEX: A commonly used European directive to control explosive atmospheres.
  • Explosive atmosphere: An area where there is a mixture of air and combustible substances under atmospheric conditions, in which the combustion can spread to the unburned mixture after ignition.
  • ATEX Zone: An area marked as an explosive atmosphere ranked based on the danger of combustible gases, dust clouds, and mists. The classification of the zones depends on the presence of explosive mixtures in the area.
  • Equipment Categories: A corresponding metric for the zones. Category 1G is the same as zone 0, and category 2G means zone 1, etc.
  • ATEX Directives: the mandatory regulations covering equipment and protective systems for use in explosive atmospheres.
  • ATEX Standards: harmonized standards composed by the directives for controlling explosive atmospheres that can aid in developing products.
  • ATEX 114 / 2014/34/EU: A directive that describes the minimum safety requirements of equipment for manufacturers
  • ATEX 153 / 1992/92/EG: A directive that describes the minimum safety requirements for employers.
  • EX rating / ATEX rating: A rating that determines the suitability of a product for specific zones.
  • Notified Body: A third party that tests products and certifies products.
  • ATEX marking / rating label: the label which displays the rating, the equipment category, the notified body number, and other characteristics.
  • ATEX Certification: Evidence that a notified body has tested the equipment and that the equipment is safe for use in explosive atmospheres.
  • Explosion protection document: A mandatory document covering a specific area’s zones.

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