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Technical Information

ATEX ATmospheres EXplosible

ATEX, an acronym derived from “Atmospheres Explosible,” refers to the European Parliament Directive 94/9/EC, updated under the ATEX 2014/34/EU Guidelines. This directive primarily establishes manufacturing standards to ensure the quality and safety of protective systems designed for use in potentially explosive atmospheres.

In industrial environments, during manufacturing, transport, storage, or even when at rest, air pollutants can create explosive atmospheres. These pollutants can be in the form of dust, gases, mists, or vapors; sometimes, they may combine to form hybrid mixtures, such as dust and gas.

ATEX Fire Triangle
ATEX Fire Triangle

To initiate a fire, the Fire Triangle principle states that fuel, heat, and a minimum of 16% oxygen are required. A similar concept applies to explosions, known as the Explosion Pentagon, which includes the additional factors of confinement and dispersion. The explosivity of a mixture is influenced by the particle size and concentration, with smaller particles providing more surface area for oxygen contact, thereby increasing explosivity. Conversely, excessive density can block oxygen access, and higher humidity levels generally reduce explosivity risk.

ATEX Explosion Pentagon
ATEX Explosion Pentagon
 

Explosion Risk

Defining the explosion risk involves the facility’s Health, Safety, and Environment (HSE) team, particularly in selecting zone criteria according to ATEX 137 99/92/CE. Once the specific zone criteria are determined, selecting the appropriate product according to the ATEX 2014/34/EU guidelines becomes straightforward.

Zones

ATmosphere – EXplosive

Equipment

Applications

Gases

Dusts

Group

Category

 

0

 

Continuously / Long Periods / Frequently

II

1G

Other Areas – Gas

 

20

(over 1000 hours per year or >10% of the time)

II

1D

Other Areas – Dust

1

 

Occasionally

II

2G

Other Areas – Gas

 

21

(10 – 1000 hours per year or 0.1 to 10% of the time)

II

2D

Other Areas – Dust

2

 

For a Short Period Only

II

3G

Other Areas – Gas

 

22

(under 10 hours per year or 0 to 0.1% of the time)

II

3D

Other Areas – Dust

ATEX 137 99/92/CE

I

M1

Mines

I

M2

Mines

ATEX 2014/34/EU

ATEX - Zone Codification