Q: Are Divisions and Zones equivalent to one another? As to the classification, they are the same. Then, the level of risk of an explosion is based on the frequency and duration of the occurrence of an explosive atmosphere. Electrical equipment can and does cause fires and/or explosions in certain atmospheres. It may exist because of repair, maintenance operations, or leakage. This was accompanied by electrically-initiated explosions of flammable gas such as fire damp (methane) and suspended coal dust. . Refrigerated The term equipment is applied both for fixed equipment and mobile equipment that are operated in such area. How to perform Hazardous Area Classification? Table 1. These are typically process areas where gases are more likely to be present. Every substance has a differing combination of properties but it is found that they can be ranked into similar ranges, simplifying the selection of equipment for hazardous areas. (equivalent to NEC Class I, Groups A and B), (equivalent to NEC Class II, Groups F and G), Group IIC is the most severe zone system gas group. This level of risk is represented by classifying the hazardous area as Zone 0, Zone 1 or Zone 2 (for gas, vapour and mist atmospheres) or Zone 21 or Zone 22 for dust atmospheres. Zone 1 - A place in which an explosive atmosphere is likely to occur in normal operation occasionally 286 natural gas explosions per year in the U.S. causing substantial damage, severe injury or loss of lives. April 2021 So the flammable range of a substance is the concentration of gases and vapors in air between the Lower Explosion Limit and the Upper Explosion Limit. Locations shall be classified depending on the properties of the flammable vapors, liquids, or gases that may be present and the likelihood that a flammable or combustible concentration or quantity is present. Adapters shall be used for connection to conduit or NPT-threaded fittings. WELDING INSPECTION The overpressure is monitored, maintained and controlled. 6: For further information on electrical systems for hazardous (classified), Informational Note No. The most standards and codes of practise for Hazardous Area Classification describe typical installations and work environments and their hazardous areas. The required protection level is linked to the intended use in the zones described below: The equipment category indicates the level of protection offered by the equipment. Electrical Equipment in Hazardous Locations - Canadian Consulting Engineer Determining the Class, Division and Group or Zone and Group is critical to correctly applying the requirements for a given hazardous location. NFPA 70, the National Electrical Code (NEC), defines area classification and installation principles. This classification method provides a description of the hazardous material that may be present, and the probability that it is present, so that the appropriate equipment may be selected, and safe installation practices followed. The last condition for an explosion is the presence of an effective ignition source in the direct contact with the fuel/air mixture. This process is called hazardous area classification. Zone 1 . Both external and internal temperatures are taken into consideration. Google use cookies for serving our ads and handling visitor statistics. 1: The term "Class I" was originally included as a prefix to, Informational Note No. This temperature is used for classification for industry and technology applications.[6]. Atmosphere containing flammable gas, flammable liquid produced vapor, or combustible liquid produced vapor mixed with air that may burn or explode, having either a MESG value greater than 0.75 mm or a MIC ratio greater than 0.80 - such as gasoline, acetone, ammonia, benzene, butane, ethanol, hexane, methanol, methane, vinyl chloride, natural gas, naphtha, propane or gases of equivalent hazard.
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