Explosive atmospheres

Explosion protection and zone classification

It binds every workplace where an explosive atmosphere may occur. The document shows three things: the zone classification, the suitability of equipment for that zone, and the protective measures taken.

What it asks for

The test is not the type of plant but whether an explosive atmosphere can form: LPG filling, paint shops, plants with flour, sugar or wood dust, battery charging rooms. Zones 0, 1 and 2 are defined for gases, vapours and mists and 20, 21 and 22 for dusts, and the numbers describe how often the atmosphere occurs.

  • Explosive atmosphere assessmentWhich substance can form an explosive atmosphere under which conditions is determined.
  • Zone classificationZones 0/1/2 for gas and 20/21/22 for dust are drawn; a non-hazardous decision is justified.
  • Equipment conformityEquipment used in a zone must match that zone by category — this is where inspections most often fail.
  • Protective measuresControl of ignition sources, ventilation, earthing and the permit regime are defined.
  • Document and revisionThe document is prepared and revised when the process, the substances or the layout change.

Declaring an area "non-hazardous" is also a decision and needs its reasoning. The workplace duty and the equipment duty are separate regimes.

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