ATEX (Explosive Atmospheres) equipment classification is a classification method used to determine the level of protection required for equipment used in potentially explosive areas.
This classification is based on the probability of the presence of an explosive atmosphere and the duration for which this atmosphere may be present. It makes it possible to determine the appropriate category of ATEX equipment for a given area.
There are two ATEX directives, ATEX 94/9/CE for equipment intended for use in explosive atmospheres, and ATEX 99/92/EC for the minimum requirements for the protection of workers exposed to the risk of explosive atmospheres.
ATEX classification is important to ensure the safety of workers in potentially hazardous environments and to prevent explosions and fires. ATEX equipment must be designed and manufactured in accordance with specific safety standards, tested and certified before being used in areas at risk of explosion.
Classification of equipment for use in ATEX zones
|HAZARDOUS AREA CLASSIFICATION||EUROPEAN/IEC CLASSIFICATION|
|Temporary behavior of flammable substances in hazardous locations||Zone |
|Equipment required for installation|
|Equipment Group||Equipment Protection Level|
|is present continuously, for long periods or frequently||Zone 0||II||Ga|
|may occur occasionally under normal operating conditions||Zone 1||II||Gb|
|is not likely to occur in normal operation or, if it does, is only of short duration||Zone 2||II||Gc|
|Dusts||is present continuously, for long periods or frequently||Zone 20||I||Da|
|may occur occasionally under normal operating conditions||Zone 21||I||Db|
|is not likely to occur in normal operation or, if it does, is only of short duration||Zone 22||I||Dc|
|SUBDIVISION OF GASES AND VAPORS|
|Equipment Usable in the Group||Gases or Vapors|
|ammonia methane ethane propane||ethyl alcohol cyclohexane n-butane||gasoline n-hexane||acetaldehyde|
|town gas, acrylonitrile||ethylene ethylene oxide||ethylene glycol||ethyl ether|
According to the same principle as for gases and vapors, dusts are divided into 3 groups.
Each type of dust has been the subject of detailed studies to determine their
flammability characteristics (INRS brochures/Silos guide, etc.). The particularity of dusts is that their auto-ignition temperatures differ depending on whether the dusts
are in clouds or in layers. As many other parameters can modify these autoignition values (particle size, humidity, ambient temperature, etc.), a calculation incorporating a safety margin must be carried out for each case.
|SPECIFIC EQUIPMENT CONDITIONS|
|Equipment without specific conditions||-|
|Equipment with special protection, can be marked||X|
|Ex component that requires additional certification before use in a hazardous area||U|
The explosion-proof enclosure must not have hot spots on its external surface that could cause self-ignition. Each device is classified according to the maximum surface temperature reached in service
Summary table of temperature classes by Gas
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