IEC
IEC 60079-10-2
Classification of Areas — Explosive Dust Atmospheres
The dust counterpart to 60079-10-1, giving Zones 20, 21 and 22 for combustible dust clouds and the separate problem of dust layers. It matters in pharma solids handling, catalyst and additive handling and coal or biomass fuel systems, where the controlling hazard is not a cloud at all but a layer that insulates a surface until it ignites. The classification therefore drives housekeeping and surface temperature limits as much as equipment selection, and a plant that has only gas classification drawings usually has no dust assessment at all.
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