What does ATEX mean?: ATEX is a certification that determines the equipment that is allowed to be used within an explosive or hazardous environment.
ATEX itself is an acronym: ATmosphere EXplosibles (French: Explosive Atmospheres)
Certification ensures that the equipment (or protective system) is fit for its intended purpose. Also that adequate information is supplied with it to ensure that it can be used safely.
Explosive environments
Explosive atmospheres in the workplace can be caused by flammable gases, mists or vapours or by combustible dusts.
For example:
- Sufficient oxygen
- Gas
- Mist
- Vapour
- Dust
- Methane
- Hydrogen
- Coal dust
When these are combined with an ignition source, these can become explosive.

What is an ignition source?
- Lightning strikes
- Open flames (This varies from a lit cigarette to welding activit)
- Mechanically generated impact sparks – For example, a hammer blow on a rusty steel surface compared to a hammer blow on a flint stone. The speed and impact angle (between surface and hammer) are important; a 90 degree blow on a surface is relatively harmless.
- Mechanically generated friction sparks – The combination of materials and speed determine the effectiveness of the ignition source. For example, 4.5 m/ssteel-steel friction with a force greater than 2 kN is an effective ignition source. The combination of aluminium and rust is also notoriously dangerous. More than one red hot spark is often necessary in order to have an effective ignition source.
- Electric sparks – A bad electrical connection or a faulty pressure transmitter. The electric energy content of the spark determines the effectiveness of the ignition source.
- High surface temperature – This can be the result of milling, grinding, rubbing, mechanical friction in a stuffing box or bearing, or a hot liquid pumped into a vessel. For example, the tip of a lathe cutting tool can easily be 600 Celsius (1100 °F); a high pressure steam pipe may be above the auto ignition temperature of some fuel/air mixtures.
- Electrostatic discharge – Static electricity can be generated by air sliding over a wing, or a non-conductive liquid flowing through a filter screen.
- Radiation
- Adiabatic compression – Air is pumped into a vessel and the vessel surface heats up.
Examples of Industries that would be required to use ATEX equipment are:
- Gas and oil platforms
- Shipping yards
- Refineries
- Petrol stations
- Industrial facilities
- Flour mills
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In Great Britain, the requirements of the Directive were put into effect through BIS Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres Regulations 1996 (SI 1996/192).
The Regulations apply to all equipment intended for use in explosive atmospheres, whether electrical or mechanical, and also to protective systems.
More information on ATEx, the directives and explosive atmospheres can be found on the Health and Safety Executive website