Hazardous Atmosphere

A hazardous atmosphere consists of a mixture of flammable substances with air in the form of gas, vapor, or mist in such proportions that it can be ignited by excessive temperatures, arcs or sparks. A hazardous area is defined as an area in which explosive atmospheres could be present, and thus could require special precaution for the construction and use of electrical equipment.

Flammable Substances

  • Flammable gases or vapors
  • Flammable liquids
  • Combustible dust
  • Ignitable fibers

Ignition Source

  • Spark
  • Static electricity
  • Temperature


Industries with potent hazmat areas: oil & gas, petrochemical industries, pharmaceutical companies, sugar factories, petrol stations, fire & rescue brigades, aircraft inspection/aviation, municipaal drainage operations, production of paint and varnish, production on chemical sites, industrial bakeries, repair shops, tank inspection, tensides, solvent factories, maritime, power plants


Potentially hazardous locations are divided into Zones

  • 0, 1, 2 for Gas, Vapor, Mist
  • 20, 21, 22 for Dust
Torches approved for usage in these zones are divided in Categories (1, 2, 3)

! An accidental explosion in a hazardous location could mean serious injury for an employee. Only an authorised supervisor should decide the Lighting ATEX Category for each Zone after strict evaluation.

Zone 0 / 20 Zone 1 / 21 Zone 2 / 22
Zone Criteria Where an explosive atmosphere is continuously present, or present for long periods of time.
(>1000 h./year)
Still safe with two faults.
Where an atmosphere is likely to occur in normal operation.
(Between 10 >1000 h./year)
Increased safety under abnormal operating conditions.
Where an explosive atmosphere is not likely to occur in normal operation and if it does occur it will exist only for a short period of time.
(< 10 h./year) Equipment which is appropriate under normal conditions.
Hazard Certain Likely Not Likely
Approved Categories 1G

US vs European Classification

What equipment is qualified for use in a hazardous area is regulated by different certifying agencies. In North America, FM (Factory Mutual) and UL (Underwriters Laboratories) provide standards, testing and certification in the United States while CSA (the Canadian Standard Association) does the same for Canada. Outside of North America, ATEX (Appareils destinés à être utilisés en ATmosphères EXplosives) and IEC (International Electrotechnical Commission) provide standards that are recognised internationally.

Substance US Classifications European Classifications
Class I Flammable Gasses, Vapors or Liquids Division 1

Division 2
Category 1/Zone 0
Category 2/Zone 1

Category 3/Zone 2
Class II Combustible Dusts Division 1

Division 2
Category 1/Zone 20
Category 2 / Zone 21

Category 3 / Zone 22
Class III Ignitable Fibers & Flyings N/A N/A

* A torch certified to Category 1 (Zone 0) is safe for use in areas rated Category 2 (Zone 1) and Category 3 (Zone 2). Conversely the opposite is not possible. This information should be taken only as a guideline. Contact us for specific details on both, US and European Directives.