ATEX Zones

ATEX zones for powder coating plants :

Zone 20

Area in which a hazardous explosive atmosphere formed by a combustible dust cloud in air is present continuously or for a long period or frequently and where dust layers of unknown or excessive thickness may be formed. Combustible dust layers on their own do not constitute a Zone 20
i.e. normally collectors / afterfilters.

As a rule, these conditions can prevail only for the inside of containers, ducts and apparatus etc. Areas, where accumulations of dusts are present, but where combustible dust clouds are not present continuously or for a long period or frequently are not included in this zone.

Zone 21

Area in which a hazardous explosive atmosphere formed by a combustible dust cloud in air is likely to occur during normal operation, and in which accumulations or layers of combustible dust will in general be present
i.e. booths

This zone can include, among others, areas in the immediate vicinity of e.g. powder filling and emptying points and areas where dust layers occur and are likely in normal operation to give rise to an explosive concentration of combustible dust in mixture with air. i.e. could be in dirty plants, close to powder hoppers, etc

Zone 22

Area in which a hazardous explosive atmosphere formed by a combustible dust cloud in air is not likely to occur in normal operation, and if it does occur, it will exist for a short period only, or in which accumulations or layers of combustible dust are present
i.e. outside booths, inside after filters after the fan or filtration area (clean side).

This zone can include, among others, areas in the vicinity of equipment containing combustible dust, from which can escape from leaks and form dust deposits