The two Directives concerned with hazardous areas are called the ATEX 95 and ATEX 137. The names are related to articles 95 and 137 of the EC treaty.
ATEX is an abbreviation from the French ‘Atmosphères Explosibles’.
Directive 94/9/EC – ATEX 95 on the approximation of the laws of the Member States concerning equipment and protective systems, intended for use in potentially explosive atmospheres.
Equipment, protective systems, and the devices to which this Directive applies must meet the essential health and safety requirements.
The Directive applies to electrical as well as mechanical equipment and applies to gases, vapors, mists, and dust atmospheres.
Directive 1999/92/EC – ATEX 137on minimum requirements for improving the safety and health protection of workers potentially at risk from explosive atmospheres.
What is an Explosive atmosphere?
An ‘explosive atmosphere’ is a mixture with air (typically 21 %), under normal atmospheric conditions, of flammable substances in the form of gases, vapors, mists, or dust in a quantity such that it is capable of forming an ignitable vapor/air mixture.
After ignition has occurred, combustion spreads to the entire unburned mixture.
The ATEX Directive does not define atmospheric conditions. In conformity to the harmonized standard EN 60079-0 the temperature range is -20 ºC to +60 ºC and the pressure range is between 0.8 and 1.1.
It should be noted that Ex products are usually designed and tested for use in an ambient temperature range of -20 ºC to +40 ºC, if not otherwise specified by the manufacturer.