Many industries and applications contain workplace hazards, especially those handling toxic chemicals that can compromise the health and safety of workers, as well as the job site. These dangerous locations within the site are classified by their risk and the likelihood of an accident occurring,
Classifications are determined by standards set by the National Electric Code (NEC) in the United States and internationally by the International Electrochemical Commissions (IEC). A hazardous area is defined in one of two ways: either the Class/Division system in North America or the Zone system recognized on an international level. The Class/Division certification system occasionally uses a Minimum Ignition Current (MIC) ratio when measuring. The MIC ratio is the least amount of current generated from an inductive spark, necessary to ignite the most accessible concentration of the target gas in the air by the minimum current from an inductive spark, required to ignite the most straightforward concentration of methane in the air.
The organization of the Class/Division system is as follows:
- Class I: gas
- Class II: dust
- Class III: fibers
- Division I: a hazard likely to be present during normal operating conditions
- Division II: a hazard present during abnormal conditions like a spill or leak
Hazards of concern are then categorized and identified through the system, labeled as Groups A through G. 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 a 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 a 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
Labeling and certification then continue with the international system, which defines areas by zones and groups:
- Zones: define the likelihood of the hazard being 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
Gas detection instrumentation will possess logos on the device to show which association has tested and evaluated the equipment to ensure its safety based on a set of strict and rigorous standards. While safety is imperative to all certifications, customers should still want to understand what circumstances their gas detector(s) is certified to face. The IECEx logo will indicate that the 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 indicate that the gas detector meets certain safety, health and environmental protection requirements. Underwriters Laboratories, certifiers using the UL symbol, identify many different types of electrical equipment. Other familiar markings companies many recognize include the CSA (Canadian Standards Association) and MSHA (The U.S. Mine Safety and Health Administration).
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 the device has been certified to United States performance and safety specifications established for methane detectors.
At Otis Instruments, safety is our top priority. We offer a variety of Wired and WireFree easy-to-use, robust and configurable gas detectors. Made in the USA, our high-quality products are capable of detecting both toxic and non-toxic gases for diverse applications and meet rigorous health and safety standards. To learn more about gas detector health and safety certification or need more specific information regarding detection for your application, contact our team today.