Explosion-proof luminaires play a critical role in ensuring safe lighting installations in areas with explosion hazards. Their purpose is to provide lighting in a way that minimises the risk of ignition and explosion in the presence of flammable substances.
What is an explosion hazard zone?
An explosion hazard zone is a specific area where there is a potential risk of a mixture of air and flammable substances, falling within the explosive concentration range between the lower and upper explosive limits. If an ignition source, such as an electric spark from a short circuit, is introduced, it can trigger the rapid combustion of flammable particles suspended in the air, which may escalate into a full-scale explosion. These areas require special safety measures and marking to ensure adequate protection against potential dangers.
Explosion hazard zones are classified based on the risk of explosion and the characteristics of the substances present in the area. Moreover, these areas must comply with the relevant safety regulations, and regular risk assessments should be conducted to ensure continuous monitoring and risk mitigation.
Classification of explosion hazard zones
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Explosion hazard zones for gases and vapor liquids
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| Zone type
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Zone definition
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Examples
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| Zone 0 | This is an area in which an explosive atmosphere in the form of a mixture of flammable substances in the form of gas, vapor, or mist with air is present continuously, for long periods, or frequently.
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chemical plant handling
flammable substances
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| Zone 1
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This is an area in which an explosive atmosphere in the form of a mixture of flammable substances in the form of gas, vapor, or mist with air is likely to occur occasionally under normal operating conditions.
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mechanical workshop using flammable substances
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| Zone 2
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This is an area in which an explosive atmosphere in the form of a mixture of flammable substances in the form of gas, vapor, or mist with air is not likely to occur under normal operating conditions, and if it does occur, it will only persist for a short period.
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warehouse where flammable substances are periodically stored; powder coating workshops
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Explosion hazard zones for dust, powders, and fibers
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| Zone type
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Zone definition
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| Zone 20
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This is an area in which an explosive atmosphere in the form of a cloud of combu-stible dust in the air is present continuously, for long periods, or frequently.
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the interior of a dust collector with filter bags, outlet and expansion chambers, and chambers with load-relieving slabs
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| Zone 21
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This is an area in which an explosive atmosphere in the form of a cloud of combustible dust in the air is likely to occur occasionally under normal operating conditions.
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interior sections of pipelines and other components of contaminated air distribution systems
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| Zone 22
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This is an area in which an explosive atmosphere in the form of a cloud of combustible dust in the air is not likely to occur under normal operating conditions, and if it does occur, it will only persist for a short period.
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chambers with extractor fans, chambers with filter regeneration systems, and outlets for clean, filtered air
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Designation of explosion hazard zones
The designation of explosion hazard zones is a critical step in ensuring safety in areas where there is a potential risk of an explosion, and it is an integral part of industrial safety management. According to the EU ATEX (from the French ‚Atmosphères Explosibles’)
directive, there are six types of explosion hazard zones. However, only three of these zones occur in the context of industrial dust extraction systems, as the others relate to environments where the flammable substances are gases, liquids and vapours. Properly understanding the type and characteristics of flammable substances is key to accurately designating the explosion hazard zones and implementing appropriate safety measures, including dust extraction systems, to minimise explosion risks.
The designation of explosion hazard zones is a complex process that requires a detailed analysis and risk assessment of the site. The first step is to identify areas where there is
a potential risk of explosive atmospheres
based on the presence of flammable substances and possible ignition sources, such as electrical sparks, open flames or hot surfaces. The boundaries of these zones are then defined based on parameters such as the lower and upper explosive limits of the substance and the environmental characteristics. Additionally, environmental factors like humidity, temperature, and pressure must be considered.
Once the boundaries of the zones are established, they must be clearly marked according to regulations and safety standards. Personnel working in these areas must also receive proper training to recognise hazards and apply preventive and emergency measures.
