Zone Descriptions Gases and Vapours
Dusts
12 3 5
Zone 1 Flammable atmosphere possible but unlikely to be present for long periods.
Zone 21 Explosive dust cloud occasionally present in normal operation.
Z1
Z21
Zone 2 Flammable atmosphere unlikely to be present except for short periods of time - typically as a result of a process fault condition.
Zone 22 Explosive dust cloud unlikely to occur in normal operation, but if it does, it will only exist for a short period.
Z22
Z2
11
10
4
1
4
6
10
12
9
5
12
8
6
3
3
6
5
6
7
1 2
3
8
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