The NEC Zone system was created to harmonize with IEC classification system, and therefore reduce the complexity of management. Sources of such hazards include gases, vapors, dust, fibers, and flyings, which are combustible or flammable. Zone 0: flammable atmosphere highly likely to be present - may be present for long periods or even continuously . Table 1. This is exactly defined as the limiting concentration of oxygen below which combustion is not possible, independent of the concentration of fuel. 1) MESG (Maximum Experimental Safe Gap) - The maximum clearance between two parallel metal surfaces that has been found under specified test conditions to prevent an explosion in a test chamber from being propagated to a secondary chamber containing the same gas or vapor at the same concentration. In the United States, the most commonly followed system is the NEC (National Electric Code), while the rest of the world generally follows the IEC (International Electrotechnical Commission). Some manufacturers claim "suitability" or "built-to" hazardous areas in their technical literature, but in effect lack the testing agency's certification and thus unacceptable for the AHJ (Authority Having Jurisdiction) to permit operation of the electrical installation/system. Definition of hazardous area zones (AS/NZS 60079.10): Zone 0 Ex s is a coding referenced in IEC 60079-0. | For Dust this would be Zone 22. Hazardous areas are classified into zones based on an assessment of the frequency of the occurrence and duration of an explosive gas atmosphere, as shown in the illustration below. NEC 2 Divisions (Div 1 2) Division I Comprising of Area Same as Zone 0 1. Group II is for explosive gases (Zone 0, 1 and 2) and Group III is for explosive dusts (Zone 20, 21 and 22). Click on the zone to learn more about the classification according to IEC 60079-10 standards. It is essential to know which zone you are working in, so that you can specify the most appropriate equipment. . You can target the Engineering ToolBox by using AdWords Managed Placements. Class II combustible dusts are grouped into one of three (3) groups: E combustible metal dusts, F combustible carbonaceous dusts or G other combustible dusts. Requirements for good HAC Drawings and Plans. The specific hazardous materials within each group and their automatic ignition temperatures can be found in Article 500 of the National Electrical Code and in NFPA 497. February 2023 A hazardous area classification drawing (also known as an area classification drawing) outlines the classifications of areas where flammable liquids, gasses or vapors are handed, processed or stored. October 2019 The zone classification for gases is divided into three zones, namely Zone 0, Zone 1 and Zone 2 and for dusts Zone 20, Zone 21 and Zone 22. Several protection strategies exist. Methane has a UEL of 17 vol%, which means when the concentration of methane in air is above the 17 vol% an explosion cannot occur even when an ignition source is present. Classification of locations, testing and listing of equipment, and inspection of installation, is typically overseen by governmental bodies. In an ordinary household this is of no concern, but if a flammable atmosphere is present, the arc might start an explosion. PROCESS OF CONTAINER Zone 2 - Explosive atmospheres are unlikely to occur or present only infrequently and for a short period only. In 29 CFR 1910.307(c)(2)(ii), OSHA requires all equipment used in a hazardous location to be marked with the class, group and operating temperature or temperature range for which it is approved. coal and charcoal), Group G Nonconductive dusts (eg. August 2020 The American Petroleum Institute publishes analogous standards in RP500 andRP505. Intrinsic safety -- This protection technique is permitted for equipment in the Class I, Zone 0 or Zone 1 locations for which it is approved. Have a think about it next time youre filling up! 1: Normal operation is considered the situation when plant, Informational Note No. Atmospheres containing non-conductive dust. The use of EPL and ATEX Category directly is an alternative for "s" marking. Atmospheres containing acetylene, hydrogen, carbon disulphide or gases and vapors of equivalent hazard. Also known as non-hazardous or ordinary locations, these locations are determined to be neither Class I, Division 1 or Division 2; Zone 0, Zone 1 or Zone 2; or any combination thereof. Each room, section, or area shall be considered individually in determining its classification. Article 505 National Electrical Code (NEC), Article 506 National Electrical Code (NEC). June 2020 Area (mm2) CFD BS EN 60079-10-1:2009 1 5.0 5.0 0.0936 12.3 - 61.7 2 5.0 2.5 0.0326 6.17 - 30.8 To minimize the risk of these fires or explosions, electrical/electronic equipment must be designed, tested and labeled as being acceptable for use in the areas in which it is installed. Q: Are Divisions and Zones equivalent to one another? October 2021 ADNOC Pit will be considered as Zone 1. National Electrical Code (NEC) and the 1998 Canadian Electrical Code (CEC) now recognize the use of the Zone system for classification of hazardous areas. Readers with specific questions should refer to the applicable standards or consult with an attorney. (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. We will go deeper into ignition assessments in another blog. It may exist because of repair, maintenance operations, or leakage. 2) MIC (Minimum Igniting Current) Ratio - The ratio of the minimum current required from an inductive spark discharge to ignite the most easily ignitable mixture of a gas or vapor, divided by the minimum current required from an inductive spark discharge to ignite methane under the same test conditions. The housing may be strong enough to contain and cool any combustion gases produced internally. 0,1 or 2: II B: I: 1 or 2: C: Acetone Benzene Butane Hexane . Workshop Container, Intelligent pressurised container | MUD logging cabin, Battery energy storage system (BESS) container, Laboratory container | workshop container | Equipment containers, Temporary refuge shelter | Toxic gas refuge | Safe haven, Offshore accommodation cabin | office container, Reefer container | Refrigerated container, Intelligent waste water treatment container, IDENTIFYING ZONE 0, ZONE 1, AND ZONE 2 HAZARDOUS AREAS, Temporary refuge (TR) shelter, toxic gas refuge (TGR), Containerised waste water treatment plant. Container Standards As to the classification, they are the same. 15 4. Hazardous Area Classification (HAC) is as follows: Definitions of hazardous area are different as per IEC and NEC. Upon detection, appropriate action is automatically taken, such as removing power, or providing notification. Since this fuel can only combust in the presence of oxygen, enough oxygen must be available for the rapid combustion to take place. Typical gas hazards are from hydrocarbon compounds, but hydrogen and ammonia are also common industrial gases that are flammable. . . For methane this is shown in the following figure. Note to paragraph (g)(4) of this section: Low ambient conditions require special consideration. LIFTING TEST Arcing electrical equipment in unclassified . 2: Where gas detection, Informational Note No. Q: Can I use a piece of equipment approved for use in a Division 1 hazardous location in a Division 2 hazardous location? Equipment is pressurised to a positive pressure relative to the surrounding atmosphere with air or an inert gas, thus the surrounding ignitable atmosphere can not come in contact with energized parts of the apparatus. Directly adjacent on the label one will find the mark of the listing agency. So yes, it is important to choose the right model and always wonder what am I assessing?. Hazardous areas are those defined as areas of potential explosion risk due to the presence of flammable gas or vapor. July 2022 Note to paragraph (g)(5)(ii)(B) of this section: An example of such a required marking is "Class I, Zone 0, AEx ia IIC T6." A Zone 1 hazardous area is classified as a place in which an explosive atmosphere consisting of a mixture with air or flammable substances in the form of gas, vapour or mist is likely to occur in normal operation occasionally. The choice of which standard to use for the hazardous area classification is something which is very important. Hazards in this group gas can be ignited very easily indeed. There are two sets of Zones: Zones 0 thru 2 are used for gases, vapors, and mists, and Zones 20 thru 22 are . Only emails and answers are saved in our archive. * Zone 1 a location in which explosive gas atmospheres are likely to occur during normal operation, or which is adjacent to a Zone 0 location. September 2020 Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro .Add the Engineering ToolBox extension to your SketchUp from the SketchUp Pro Sketchup Extension Warehouse! The basis for the classification into zones is the duration of the presence of the potentially explosive atmosphere: The longer it is present, the more critical the zone. Therefore, it is very important to make sure that you are using a suitable luminaire for your application by choosing your fitting based on its suitability for the Zone in which it will be located. Electrical equipment installation in atmosphere with flammable gases or vapors, flammable liquids, combustible dusts, ignitable fibers or flyings represents a risk for fire and explosion. All areas in the facility that are not Zone 0, Zone 1, or Zone 2 are considered unclassified. Temporary Refuge Table 1. Class I, Zone 0 = Area Classification, AEx = Symbol for equipment built to American specifications, ia = Type of protection designations, IIC = Gas classification group (as required), T6 = Temperature Classification, [46 FR 4056, Jan. 16, 1981; 46 FR 40185, Aug. 7, 1981; 72 FR 7210, Feb. 14, 2007], Occupational Safety & Health Administration. Area Classification - Hazardous Locations are classified by the likelihood of an ignitable concentration of combustible material being present. All threaded conduit shall be threaded with an NPT (National (American) Standard Pipe Taper) standard conduit cutting die that provides -in. * Zone 2 a . The Occupational Safety and Health Administration (OSHA) has adopted these hazardous classifications and all except Groups are defined in 29 Code of Federal Register (CFR) 1910.399. In many industrial, commercial, and scientific settings, the presence of such an atmosphere is a common, or at least commonly possible, occurrence. 1994-2020, W.W. Grainger, Inc. All Rights Reserved. In the United Kingdom, Sira and Baseefa are the most well known such bodies. >> NEC: Class I, Division 2, Group D. | IEC: Zone 2, Group II. In other cases, the atmosphere is normally non-hazardous, but a dangerous concentration can be reasonably foreseensuch as operator error or equipment failure. Zone 1 - Explosive atmospheres are likely to occur. NEC Div 1 Zone 1 Div 2 Zone 2Flammable during normal operation Most Safer Zone IEC Zone 0 DESRIPTIONHighly Flammable for long period DEFINITIONFlammable atmosphere present continuously (Typically 1000 hours / year). May 2021 Explosion Hazardous Areas are divided into zones according to risk probabilities. A differentiation is made between gas Ex zones and dust Ex zones: Gas Ex zones are 0/1/2 and dust Ex zones are 20/21/22. IEC 60079-10-1 covers classification of explosive gas atmospheres, and IEC 60079-10-2 explosive dust. Area classification documentations are reviewed and updated to reflect process changes. Then, the level of risk of an explosion is based on the frequency and duration of the occurrence of an explosive atmosphere. September 2018 A more quantitative method is described in IEC 60079-10-1 but also more sophisticated numeric mathematical models can be used like Computational Fluid Dynamics. The escaping (hot) gases must sufficiently cool down along the escape path that by the time they reach the outside of the enclosure not to be a source of ignition of the outside, potentially ignitable surroundings. Zone defines thegeneral nature if it is a gas or dust and theprobabilityof hazardous material being present in an ignitable concentration in the surrounding atmosphere.