ATEX is the name commonly given to the two European Directives for controlling explosive atmospheres:
1) 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.
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 un-burned mixture.
Gases, vapors, mists and dusts can all form explosive atmospheres with air. Hazardous area classification is used to identify places where, because of the potential for an explosive atmosphere, special precautions over sources of ignition are needed to prevent fires and explosions.
Classification of an area
Hazardous areas are divided into Zones (European and IECEX method) or Classes and Divisions (North American method) according to the likelihood of a potentially explosive atmosphere being present.