What is ATEX?
ATEX is the European framework for equipment and workplaces where an explosive atmosphere can occur. The name comes from the French "ATmosphères EXplosibles". This page gives a practical overview for anyone who has to select or buy equipment for a hazardous area. Each section links to the ATEX Wiki for the full detail.
The two ATEX directives
- Directive 2014/34/EU (equipment): applies to manufacturers, importers and distributors. Equipment and protective systems for explosive atmospheres must meet its essential health and safety requirements and carry the CE marking and the Ex mark. It replaced Directive 94/9/EC on 20 April 2016. More about Directive 2014/34/EU.
- Directive 1999/92/EC (workplace): applies to employers. They must assess explosion risks, classify hazardous areas into zones and use suitable equipment in each zone. More about Directive 1999/92/EC.
How the two work together is explained in The Two ATEX Directives Explained.
What is an explosive atmosphere?
An explosive atmosphere is a mixture of air and flammable substances in the form of gases, vapours, mists or dusts in which, after ignition, combustion spreads to the entire unburned mixture. Typical locations include refineries, chemical plants, offshore platforms, fuel stations, mines, grain and flour handling, and spray painting. Read more in What is an Explosive Atmosphere?
ATEX zones
Hazardous areas are classified into zones, based on how often and for how long an explosive atmosphere is present.
| Gas, vapour or mist | Dust | Explosive atmosphere present |
|---|---|---|
| Zone 0 | Zone 20 | Continuously, for long periods or frequently |
| Zone 1 | Zone 21 | Likely to occur occasionally in normal operation |
| Zone 2 | Zone 22 | Not likely in normal operation and, if it occurs, only for a short period |
More detail: Introduction to Zone Classification, Zone 0, 1 and 2 for Gases and Zone 20, 21 and 22 for Dusts.
Equipment categories: which equipment for which zone?
Equipment group I covers mines (categories M1 and M2). Group II covers all other industries and is divided into three categories, each matching a zone.
| Zone | Minimum equipment category | Equipment protection level (EPL) |
|---|---|---|
| Zone 0 / Zone 20 | Category 1 (1G / 1D) | Ga / Da |
| Zone 1 / Zone 21 | Category 2 (2G / 2D) | Gb / Db |
| Zone 2 / Zone 22 | Category 3 (3G / 3D) | Gc / Dc |
A higher category may always be used in a lower-risk zone, so Category 1 equipment is also suitable for Zone 1 and Zone 2. More detail: Equipment Groups I and II, Equipment Categories Explained and Equipment Protection Levels (EPL).
Temperature classes
For gas atmospheres, the temperature class shows the maximum surface temperature of the equipment. It must stay below the auto-ignition temperature of every gas that can be present.
| Class | T1 | T2 | T3 | T4 | T5 | T6 |
|---|---|---|---|---|---|---|
| Maximum surface temperature | 450 °C | 300 °C | 200 °C | 135 °C | 100 °C | 85 °C |
For dust atmospheres, the maximum surface temperature is stated directly in °C, for example T135 °C. See Temperature Classes (T1-T6).
Reading an ATEX marking
A typical marking on equipment for a gas atmosphere looks like this: CE 0081 (Ex) II 2 G Ex db IIC T4 Gb
| CE 0081 | CE marking, with the number of the notified body involved in production monitoring |
| (Ex) | The Ex symbol in a hexagon: the specific marking for explosion protection |
| II | Equipment group II (all industries except mines) |
| 2 G | Category 2, for gas atmospheres (suitable for Zone 1 and Zone 2) |
| Ex db | Type of protection, here a flameproof enclosure (d) at level b |
| IIC | Gas group: IIC is the most demanding group and also covers IIA and IIB |
| T4 | Temperature class: maximum surface temperature 135 °C |
| Gb | Equipment protection level |
More detail: ATEX Marking Requirements and Reading ATEX Labels.
ATEX and IECEx
ATEX is mandatory for equipment placed on the market in the EU and the EEA. IECEx is an international certification scheme based on the same IEC 60079 series of standards and is accepted in many countries outside Europe. Many products carry both. See ATEX vs IECEx and ATEX Beyond Europe.
Choosing ATEX equipment
- Find out the zone of the area where the equipment will be used. The employer records this in the explosion protection document.
- Choose equipment with a matching category or EPL (see the table above).
- Check the gas group (IIA, IIB, IIC) or dust group (IIIA, IIIB, IIIC) of the substances present.
- Check the temperature class against the lowest auto-ignition temperature present.
- Check the ambient temperature range and any specific conditions of use, shown by an X after the certificate number.
ATEXshop.com supplies ATEX and IECEx certified equipment, such as intrinsically safe tablets, explosion proof smartphones, ATEX cameras, ATEX flashlights and ATEX radios. Not sure which equipment fits your zone? Contact us.
Frequently asked questions
Is ATEX mandatory?
Within the EU and the EEA, yes. Equipment for explosive atmospheres must comply with Directive 2014/34/EU before it is placed on the market, and employers must follow the national rules that implement Directive 1999/92/EC.
Can I wear a watch or hearing aid in an ATEX zone?
This is a common question about small battery-powered personal items. Whether they are acceptable depends on the zone and on the site's own risk assessment and rules. In Zone 0 and Zone 20, equipment must be Category 1. Check with the person responsible for the explosion protection document before taking personal electronics into a hazardous area.
Where can I learn more?
The ATEX Wiki covers ATEX in depth across 21 sections, from the fundamentals to inspection, standards and international certification. A good place to start is What is ATEX?