Equipment Protection Level
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Equipment Protection Level

What is an explosive hazardous area? There are many different classifications, markings and codes. This blog post will give you a quick introduction to the subject.

Andreas Parr Bjørnsund
December 18, 2014


Explosives hazardous areas occur where flammable liquids, vapors, gases or combustible dusts are likely to occur in quantities sufficient to cause a fire or explosion. Often, these atmospheres are created where gas, vapors, dusts and liquids are in contact with oxygen. Hazardous areas are divided into zones, where the probability of a hazardous atmosphere being present governs the explosion risk. Some areas are more hazardous than others, since it is more likely that there are gasses present. There are explosive gas atmospheres, explosive dust atmospheres, and the explosive atmospheres which may exist in coal mines. The table below explains the relationship between the various Zones, Groups, Categories and EPL codes.


Area Classification Equipment category/level
Explosive Consentration Zone Risk Equipment Group Atex Category IEC – EPL
Often/longer periods 0 High, safe with 2 faults II 1G Ga
Occasionally 1 High, safe with 1 fault II 2G (1G) Gb (Ga)
Rarely/most likely never 2 Normal II 3G (1G/2G) Gc (Ga/Gb)
Often/longer periods 20 High, safe with 2 faults II* 1D Da
Occasionally 21 High, safe with 1 fault II* 2D (1D) Db (Da)
Rarely/most likely never 22 Normal II* 3D (1D/2D) Dc (Da/Db)
High, safe with 2 faults I M1 Ma
High, safe with 1 fault I M2 Mb
* According to IEC 60079-0, 2007, equipment group for dust is to be group III


Where can you find hazardous areas?

Hazardous areas can occur in many industries and unexpected locations, including, but not limited to:

  • Automotive refueling stations or petrol stations
  • Oil refineries, rigs and processing plants
  • Chemical processing plants
  • Printing industries, paper and textiles
  • Hospital operating rooms
  • Pharmaceutical industry
  • Aircraft refueling and hangars
  • Surface coating industries
  • Underground coal mines
  • Sewerage treatment plants
  • Gas pipelines and distribution centers
  • Grain handling and storage
  • Woodworking areas
  • Sugar refineries
  • Metal surface grinding, especially aluminum dusts and particles


Sources: BARTEC TECHNOR and IECEx websites.