Zone 0

Area in which an explosive gas/vapour atmosphere is present continuously or for long periods or frequently

Zone 1

Area in which an explosive gas atmosphere is likely to occur in normal operation occasionally

Zone 2

Area in which an explosive gas atmosphere is not likely to occur in normal operation and if it does occur, is likely to do so only infrequently and will exist for a short period only

Zone 20

Place in which an explosive atmosphere in the form of a cloud of combustible dust in air is present continuously, or for long periods or frequently

Zone 21

Place in which an explosive atmosphere in the form of a cloud of combustible dust in air is likely to occur in normal operation occasionally

Zone 22

Place in which an explosive atmosphere in the form of a cloud of combustible dust in air is not likely to occur in normal operation but, if it does, will persist for a short period only

Gas

Dust

Equipment Category

Zone 0

Zone 20

1

Zone 1

Zone 21

1 or 2

Zone 2

Zone 22

1, 2 or 3