What are Gas Detector Certifications and Why do they Matter?

What are Gas Detector Certifications and Why do they Matter?

Dave Wagner | Monday, May 3, 2021

Have you ever turned over your gas detector and looked at the collection of logos and fine print on the back label? What do all those symbols represent, and what does all that text mean? One of the biggest concerns in an industrial workplace is the potential for fire and explosion. Under the right circumstances, electrical or electronic equipment can ignite any flammable, combustible or ignitable gases, vapors, liquids, dusts or fibers that may be in the atmosphere. This includes everything from flashlights to forklifts and yes, even your gas detector. The logos on that label are your assurance that the gas detector that you are relying on to keep you safe won’t unintentionally put you in harm’s way.


Hazards in the workplace are too numerous to count. A hazardous location is specifically defined as an area where a combustible or flammable material is or has the potential to be present. Hazardous locations are classified by the type of combustible hazard and the likelihood of it being present in the area. These classifications are determined by standards set by the National Electric Code (NEC) in the United States and internationally by the International Electrochemical Commissions (IEC). You’ll see a hazardous area defined in one of two ways: either the Class/Division system in North America or the Zone system which is recognized internationally. 

The Class/Division certification system sometimes uses a Minimum Ignition Current (MIC) ratio when measuring. The MIC ratio is the minimum current generated from an inductive spark necessary to ignite the most easily ignitable concentration of the target gas in air divided by the minimum current from an inductive spark required to ignite the most easily ignitable concentration of methane in air. The Class/Division system is organized in the following way:

  • Classes
    • Class I: gas
    • Class II: dust
    • Class III: fibers
  • Divisions
    • Division I: the hazard is likely to be present during normal operating conditions
    • Division II: the hazard is present during abnormal conditions like a spill or leak

This system also defines Groups A through G, which covers the particular hazard of concern. For example:

  • Group A: Acetylene
  • Group B: Hydrogen, butadiene, ethylene oxide, propylene oxide, acrolein and other gases with a MIC ratio less than 0.40
  • Group C: Ethyl ether, ethylene, acetaldehyde, cyclopropane and other gases with an MIC ratio greater than 0.40 but less than 0.80
  • Group D: Acetone, ammonia, benzene, butane, ethanol, gasoline, methane, natural as, naphtha, propane and other gases with an MIC ratio greater than 0.80
  • Group E: Combustible metal dusts including aluminum, magnesium and alloys of aluminum and magnesium
  • Group F: Combustible carbonaceous dusts containing more than 8% volatile compounds such as carbon black, coal and coke dust
  • Group G: Combustible dusts such as flour, starch, grain, wood, plastic, chemicals and other combustible dusts not included in groups E or F

The more modern international system defines areas by zones and groups:

  • Zones: define the likelihood of the hazard to be present
    • Zone 0: The hazard is present continuously and for long periods of time
    • Zone 1: The hazard is likely to be present in normal operating conditions
    • Zone 2: The hazard is not likely to be present in normal conditions for an extended period of time
  • Groups: tell you the particular type of hazard
    • Group I: the hazard is specific to the mining industry
    • Group II: will have a subset telling you the hazard is gaseous in nature
      • A: methane, propane, and other similar gases
      • B: ethylene and gases that present similar hazard risk
      • C: acetylene, hydrogen or other similar hazards
    • Group III: dusts and other subsets by particle size and material type


The logos on the labels of gas detectors show which association has tested and evaluated the equipment to ensure its safety based on a set of applicable standards. Some of these associations are government run, some are regulatory agencies, and some are private sector “recognized bodies” that test and certify equipment commercially for profit. It’s important to know what type of association is certifying the gas detectors you’re using and the standards they put in place to consider a device to be certified. While safety is a key driver of all certifications, you’ll still want to understand what circumstances your gas detector is certified to face.

An example of certification labels found on a gas detector depicting
how the detector is certified for use. The IECEx logo shows that
this detector is certified to IEC and ATEX standards, and the CE Mark
is a universal marking for Europe similar to the UL logo in the
United States. These marks signify that this gas detector meets
certain safety, health and environmental protection requirements.

The most commonly recognized safety certification organization in the United States is Underwriters Laboratories, whose familiar UL symbol can be found on many different types of electrical equipment. Other familiar markings include CSA (Canadian Standards Association), MSHA (The U.S. Mine Safety and Health Administration), ANZE, which shows equipment is certified by a recognized body to Australian standards, and New Zealand’s IECEx, which declares certification by a recognized body to IEC and ATEX standards. These markings indicate the equipment is certified for use and to the standards of EU or INMETRO, showing that a device is certified to Brazil’s standards. There are many other symbols and logos specific to countries or regions, but these are far too numerous to mention.

Many agencies only certify a gas detector as being explosion proof, meaning that any ignition will be contained within the device and will not impact the outside atmosphere. This process is intrinsically safe, meaning that the gas detector won’t create a spark that will ignite a hazardous atmosphere.

Some agencies commonly certify that their devices comply with strict performance guidelines and specifications as well. A device marked with the CSA logo and a marking that it has been certified to standard 22.2 No. 152 indicates that the part of a device that detects combustible gas is up to Canada’s performance standards required for a combustible gas detector. Similarly, the MSHA logo and a label stating that it is a permissible methane detector indicates that the device has been certified to United States performance and safety specifications established for methane detectors.

No one will ever try to convince you that these certification markings are easy to understand. If you have trouble understanding the fine print, always refer to the gas detector user’s manual for specific information.

It’s important to look for familiar logos as your first indication that the equipment you’re carrying is safe to put in your tool belt and take to work. Talk to one of our experts for more information on gas detector labeling, safety procedures and other need-to-know gas detector information.  

Dave Wagner is director of product knowledge and application engineering at Industrial Scientific.