An ATEX (the French acronym for an explosive atmosphere) is said to be explosive when its usual composition is not explosive but which, due to foreseeable circumstances, may vary in function such that it becomes explosive (the danger exists in the potential state). The foreseeable circumstances may be due to different stages of a manufacturing process, to incidents or accidents (seal leaks, a burst pipe, power failure, etc.) or weather conditions (high ambient temperature).
ATEX probability or explosive atmosphere: this is a notion introduced by the so-called European ATEX directive which defines six areas. The likelihood of an explosive atmosphere is said to be high when it involves zones 0 and 20 (the explosive atmosphere is continuously present); medium to low if it concerns zones 1 and 21 (the explosive atmosphere is liable to form under normal operation); and finally very low if it is included in zones 2 and 22 (the explosive atmosphere is not likely to occur in normal operation and if it occurs, can only subsist for short periods). 
The ATEX directives are designed to increase the protection of employees in explosive areas by making certain organizational and technical measures mandatory.
CNPP assists customers in assessing and treating ATEX Explosion Risks and training personnel exposed to a potential explosion.

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