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ATEX zoning
What is ATEX?
Hazardous places are subdivided into zones according to the frequency of occurrence and duration of potentially explosive atmospheres.
This categorisation gives rise to the extent of measures required according to Annex II Part A of Directive 1999/92/EC in conjunction with Annex I of Directive 94/9/EC. Explosive atmospheres can be caused by flammable gases, mists or vapors or by combustible dusts. If there is enough of the substance, mixed with air, then all it needs is a source of ignition to cause an explosion.
Explosions can cause loss of life and serious injuries as well as significant damage. Preventing releases of dangerous substances, which can create explosive atmospheres, and preventing sources of ignition are two widely used ways of reducing the risk.
Using the correct equipment can help greatly in this. The Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) place duties on employers to eliminate or control the risks from explosive atmospheres in the workplace.
ATEX is the name commonly given to the two European Directives for controlling explosive atmospheres:
Directive 99/92/EC (also known as 'ATEX 137' or the 'ATEX Workplace Directive') on minimum requirements for improving the health and safety protection of workers potentially at risk from explosive atmospheres.
Directive 94/9/EC (also known as 'ATEX 95' or 'the ATEX Equipment Directive') on the approximation of the laws of Members States concerning equipment and protective systems intended for use in potentially explosive atmospheres.
What is an explosive atmosphere?
An explosive atmosphere is defined as a mixture of dangerous substances with air, under atmospheric conditions, in the form of gases, vapors, mist or dust in which, after ignition has occurred, combustion spreads to the entire unburned mixture.
Where can explosive atmospheres be found?
Many workplaces may contain, or have activities that produce, explosive or potentially explosive atmospheres. Examples include places where work activities create or release flammable gases or vapors, such as vehicle paint spraying, or in workplaces handling fine organic dusts such as grain flour or wood.
Who is responsible to define the ATEX zones of an industrial workplace?
This is the duty of the management or owners of the industrial producer. RUWAC cannot make the decision about your applicable ATEX zone!
What is the meaning of ATEX zoning?
ATEX zones classify an area according to the frequency or possibility for the occurance of an explosive dust/air and/or gas/air mixture. The level of the explosion risk is NOT defined by the ATEX zone but absolutely identical in each zone! In order to determine the level of risk it is necessary to get accurate information about the Suction Media.
Determining the ATEX Zone
| European and IEC Classification | Definition of zone or division | North American Classification |
| Zone 0 (gases / Vapors) | An area in which an explosive mixture is continuously present or present for long periods | Class I Division 1 (gases) |
| Zone 1 (gases / Vapors) | An area in which an explosive mixture is likely to occur in normal operation | Class I Division 1 (gases) |
| Zone 2 (gases / Vapors) | An area in which an explosive mixture is not likely to occur in normal operation and if it occurs it will exist only for a short time. | Class I Division 2 (gases) |
| Zone 20 (dusts) | An area in which an explosive mixture is continuously present or present for long periods | Class II Division 1 (dusts) |
| Zone 21 (dusts) | An area in which an explosive mixture is likely to occur in normal operation | Class II Division 1 (dusts) |
| Zone 22 (dusts) | An area in which an explosive mixture is not likely to occur in normal operation and if it occurs it will exist only for a short time. | Class II Division 2 (dusts) |
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