HazLoc Certifications & Compliance: Part II

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Hazardous locations, or HazLoc, are classified areas that contain gases, vapors, dust or fibers that create a risk of fire or explosions. Examples of these locations include oil rigs, construction sites, aircraft hangers, health care facilities, power generation plants, coal mines and sugar refineries. To operate a business in a hazardous location and guarantee that the work site is safe, there are standards and certifications that must be met. ATEX and IEC are the primary groups that enforce these standards. As part of the process, hazardous areas are classified using a series of defining criteria.

HazLoc Area Classifications

There are two systems that are used to classify hazardous locations: the zone system and the class/division system.

HazLoc Classification: The Zone System

The zone system is commonly used with ATEX regulations and is made of zones and groups.

Zones define the nature of the hazardous material and the probability of it being present in the area.

  • Zone 0: Ignitable concentrations of flammable gases or vapors are present continuously.
  • Zone 1: Ignitable concentrations of flammable gases or vapors are likely to be present under normal operating conditions.
  • Zone 2: Ignitable concentrations of flammable gases or vapors are not likely to be present under normal operating conditions.
  • Zone 20: Combustible dusts or ignitable fibers or flyings are present continuously.
  • Zone 21: Combustible dusts or ignitable fibers or flyings are likely to be present under normal operating conditions.
  • Zone 22: Combustible dusts or ignitable fibers or flyings are not likely to be present under normal operating conditions.

Groups define the specific type of hazardous material and the location of the area.

  • Group I includes mines that are susceptible to flammable gases.
  • Group II includes areas other than mines that are susceptible to explosive gases.
  • IIA areas contain propane, acetone, butane, methane, petrol, hexane, paint solvents, or gases and vapors of equivalent hazard.
  • IIB areas contain ethylene, propylene oxide, ethylene oxide, butadiene, cyclopropane, ethyl ether, or gases and vapors of equivalent hazard.
  • IIC areas contain acetylene, hydrogen, or gases and vapors of equivalent hazard.
  • Group III includes areas susceptible to explosive dusts.
  • IIIA areas contain combustible fibers.
  • IIIB areas contain non-conductive dust.
  • IIIC areas contain conductive dust.

HazLOC Classifications: The Class/Division System

The class/division system is commonly used with IEC regulations and is made of classes, divisions and groups.
Classes define the nature of the hazardous material present in the area.

  • Class I – the presence of flammable gases or vapors in quantities sufficient to produce explosive or ignitable mixtures.
  • Class II – the presence of combustible dust in quantities sufficient to produce explosive or ignitable mixtures.
  • Class III – the presence of easily ignitable fibers or flyings in quantities sufficient to produce explosive or ignitable mixtures.

Divisions define the probability of the material being present in the area.

  • Division 1 indicates there is a high probability the material will produce an explosive or ignitable mixture due to it being continuously or intermittently present during normal operating conditions.
  • Division 2 indicates there is low probability the material will produce an explosive or ignitable mixture due to it only being present under abnormal conditions such as equipment failure.


Groups define the specific type of hazardous material in the area.

  • Group A – acetylene
  • Group B – hydrogen, butadiene, ethylene oxide, propylene oxide, acrolein or gases of equivalent hazard
  • Group C – carbon monoxide, hydrogen sulfide, cyclopropane, ethyl, isoprene, ethylene or gases of equivalent hazard
  • Group D – gasoline, acetone, ammonia, benzene, butane, ethanol, hexane, methanol, methane, vinyl chloride, natural gas, naphtha, propane or gases of equivalent hazard
  • Group E – aluminum, magnesium, bronze, chromium, titanium, zinc, or other combustible dusts that present similar hazards in connection with electrical equipment
  • Group F – carbonaceous dusts, carbon black, coal black, charcoal, coal, coke dusts or other dusts that present an explosion hazard
  • Group G – combustible dust not listed in Group E and F such as flour, grain, starch, sugar, wood, plastics and chemicals

To certify products to operate in hazardous locations, it is imperative that the area is classified. While there are some differences, the testing processes for ATEX and IECEx are almost identical so the certifications are often pursued jointly. Classifying a hazardous location under the zone and class/division system makes the certification process more efficient.

Read HazLOC Certifications & Compliance: Part I

Design for Certification

With a “design for certification” approach, Sealevel can manage the entire process of custom product development certified to many military and commercial standards including:

  • Class I, Div1; Class I, Div 2 Hazardous Areas
  • MIL-STD-810 (Environmental)
  • MIL-STD-1472 (Heat Transfer)
  • MIL-STD-901 (Shock – Marine)
  • MIL-STD-464 (EMC)
  • MIL-STD-461 (Power Supply Specification)
  • MIL-STD-167 (Vibration – Marine)
  • NEMA, IP and ATEX
  • FCC, CE
  • UL, CSA

To learn more, check out our series on “Meeting & Exceeding Standards”:
Aerodynamic Hazards
Pyroshock, Gunfire and Ballistics
Shock and Vibration
Atmospheric Conditions
Environmental Contaminants
Water Intrusion
Temperature Extremes & Shock
Electromagnetic Interference