The last condition for an explosion is the presence of an effective ignition source in the direct contact with the fuel/air mixture. Zone 1 if gas group & temp. National Electrical Code (NEC) and the 1998 Canadian Electrical Code (CEC) now recognize the use of the Zone system for classification of hazardous areas. area in which an explosive gas atmosphere is not likely to occur in normal operation, but, if it does occur, will exist for a short period only (less than 0,1% of the time), Window breakage, cracks plaster, light damage to buildings, Collapse of wood or asbestos siding of homes, Collapse of walls made of concrete blocks, Reinforced concrete structures severely damaged, Flames and hot gases (including hot particles), Mechanically generated impact, friction and abrasion, Stray electric currents, cathodic corrosion protection, Radio frequency (RF) electromagnetic waves from 10, Exothermic reactions, including self-ignition of dusts, EI 15 Energy Institute 15, mostly for on- and offshore oil and gas applications. September 2021 Zone 0 is an area in which an explosive atmosphere is present continuously for long periods of time or will frequently occur. December 2021 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. Hazardous areas are classified into zones based on an assessment of the frequency of the occurrence and duration of an explosive gas atmosphere, as follows: Zone 0: An area in which an. Group is divided in three groups where Group I is reserved for mining locations. November 2022 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. Terminology for both hazards and protective measures can vary. In Europe the ATEX 114 Directive (2014/34/EU) is applicable to equipment that is used in hazardous area's. The International Electrotechnical Commission publishes the 60079 series of standards[2] which defines a system for classification of locations, as well as categorizing and testing of equipment designed for use in hazardous locations, known as "Ex equipment". Entire Vapour space of storage tank. Feedback From Clients No representation is made that the information or references are complete or remain current. The simplest is to minimize the amount of electrical equipment installed in a hazardous location, either by keeping the equipment out of the area altogether, or by making the area less hazardous (for example, by process changes, or ventilation with clean air). 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. Raytec do not currently offer any lighting solutions for Zone 0. Enclosures can be pressurized with clean air or inert gas, displacing any hazardous substance. In this article we will look at what defines Zone 0, Zone 1 and Zone 2 hazardous area classifications and the considerations for specifying lighting into each area. Container Accessories Note to paragraph (c)(3) of this section: The National Electrical Code, NFPA 70, contains guidelines for determining the type and design of equipment and installations that will meet this requirement. The NEC Zone system was created to harmonize with IEC classification system, and therefore reduce the complexity of management. Upon detection, appropriate action is automatically taken, such as removing power, or providing notification. The first thing to understand is that much like the metric vs imperial measuring systems, the United States uses its own methodology which differs from much of the world. It is good to be aware of the fact that the mixture of flammable gas with oxygen has an optimum point where the combustion is most severe and leads to the highest explosion pressure. The classification process requires the participation of operations, maintenance, safety, electrical and instrumentation professionals; and the use of process diagrams, material flows, safety data sheets, and other pertinent documents. 41 gas explosions per year occur within the UK and app. LIFTING TEST Ambient Temperature (-20C to +40C if not marked) Establish Zone Based on "IEC 60079-10". PROCESS OF CONTAINER Where there is potential for an explosive atmosphere, special precautions are needed to prevent fires and explosions. For non-ambient conditions, like process reactors or other enclosed systems, the Limiting Oxygen Concentration is often used for the prevention of explosive atmospheres within those enclosed areas. Container Test In the US, the independent National Fire Protection Association (NFPA) publishes several relevant standards, and they are often adopted by government agencies. So for an explosion there must be enough fuel. SIGN UP FOR EMAILGet more great content in your inbox. When equipment must be placed in a hazardous location, it can be designed to reduce the risk of fire or explosion. 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. Although every application is different, for the ease of monitoring and specification each hazardous area is classified as a particular level or zone. area in which an explosive gas atmosphere is present continuously, or for long periods, or frequently (more than 10% of the time). The following Equipment Groups and Categories are applicable: Equipment in this category is only intended for use in the underground areas of mines, as well as those areas of surface installations of such mines endangered by firedamp and/or combustible dusts. Comparison of Zones and Divisions. Is intended for us in Zone 2 (gases) or Zone 22 (dusts). The value is represented is volume percentage of oxygen. Iso Container A Class I, Division 1 or Division 2 location may be reclassified as a Class I, Zone 0, Zone 1, or Zone 2 location only if all of the space that is classified because of a single flammable gas or vapor source is reclassified. All rights reserved. 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 October 2019 Zone 2 - Explosive atmospheres are unlikely to occur or present only infrequently and for a short period only. 1910.307 (g) (2) A light switch may cause a small, harmless spark when switched on or off. The following content is only related to flammable substances and not to pyrotechnic substances or other instable substances, among those who can decompose. 29 CFR 1910.307 Hazardous (classified) Locations . POSITIVE PRESSURE Electrical equipment can and does cause fires and/or explosions in certain atmospheres. Equipment should be tested to ensure that it does not exceed 80%[according to whom?] The American Petroleum Institute publishes analogous standards in RP500 andRP505. Dn 1 - a Ce e . The NEMA enclosure rating or IP code may also be indicated, but it is usually independent of the Classified Area suitability. A60 taper per foot. Zone 2 Explosive Mixtures not likely to occur /occur short duration in normal operation (lt10 Hrs/ Yr). Hazards in this group gas can be ignited very easily indeed. Powder Filling "q" -- This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved. Adapters shall be used for connection to conduit or NPT-threaded fittings. Division defines the likelihood of the hazardous material being present in an explosive or ignitable concentration.Class I flammable gases and vapors are grouped into one of four groups(Groups A, B, C or D)based on their physical properties and the ease in which they can be ignited. However, the following provisions modify this marking requirement for specific equipment: Fixed lighting fixtures marked for use in Class I, Division 2 or Class II, Division 2 locations only need not be marked to indicate the group; Fixed general-purpose equipment in Class I locations, other than lighting fixtures, that is acceptable for use in Class I, Division 2 locations need not be marked with the class, group, division, or operating temperature; Fixed dust-tight equipment, other than lighting fixtures, that is acceptable for use in Class II, Division 2 and Class III locations need not be marked with the class, group, division, or operating temperature; and. Table 1. 10: For information on electrical resistance trace heating for hazardous (classified), Informational Note No. . Determined to be none of the above. FREEZER In the US, the National Electrical Manufacturers Association (NEMA) defines standards for enclosure types for a variety of applications. [10][11] Some of these are specifically for hazardous locations: All equipment certified for use in hazardous areas must be labelled to show the type and level of protection applied. It is always balancing between not defining such areas too large (with highly costs for prevention of ignition sources) or too small (unsafe situations). 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. For dusts: Zone 20, Zone 21 and Zone 22. The two general approaches are: Several techniques of flame-proofing exist, and they are often used in combination: Equipment has flameproof gaps (max 0.006" (150m) propane/ethylene, 0.004" (100m) acetylene/hydrogen), Equipment can be installed in ANY housing provided to IP54.A 'Zener Barrier', opto-isolator or galvanic unit may be used to assist with certification. Empirical testing is done to determine parameters such as the maximum experimental safe gap (MESG), minimum igniting current (MIC) ratio, explosion pressure and time to peak pressure, spontaneous ignition temperature, and maximum rate of pressure rise. When the concentration of methane is beneath the LEL, an explosion cannot occur, even when an ignition source is present. 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. The Zone system is based on Article 505/506 of the National Electrical Code (NEC) and follows the international method of area classification as developed by the International Electrotechnical Commission (IEC). Often an area classification plan view is provided to identify equipment ratings and installation techniques to be used for each classified area. Class 1/Div 2 ATEX Zone 2 Computers. August 2018 When working in or specifying equipment for use in hazardous environments, we see a lot of confusion in the industry regarding the different certifications and requirements. Safe for the hazardous (classified) location. Offshore Accommodation Module A spark or high heat must also be present. This can be achieved by blanketing with nitrogen or carbondioxide. There are three zones for gas: Zone 0, Zone 1 and Zone 2. 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. Atmosphere containing a flammable gas, a flammable liquid produced vapor, or a combustible liquid produced vapor mixed with air that may burn or explode, having either a MESG (Maximum Experimental Safe Gap)1) value less than or equal to 0.45 mm or aMIC (Minimum Igniting Current)2) ratio less than or equal to 0.40 - such as hydrogen or fuel and combustible process gases containing more than 30% hydrogen by volume - or gases of equivalent hazard such as butadiene, ethylene oxide, propylene oxide and acrolein. Area Classification - Hazardous Locations are classified by the likelihood of an ignitable concentration of combustible material being present. Class II, Div 2 Class III, Div 1 nR 3G Zone 2 Gc Class III, Div 2 Pressurised Room px 60079-13 2G Zone 1 Gb Zone 21 Db 2D Pressurised Room FM3611 NFPA 496 Class I, Div 1 Class I, Div 2 Class II, Div 1 Class II, Div 2 py 2G Zone 1 Gb pz 3G Zone 2 Gc Zone 22 Dc 3D pv Non-hazardous Gb/GC Optical Radiation op sh 60079-28 1G Zone 0 Ga Zone 20 Da 1D . 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. Magnesium, Titanium), IIB Nonconductive dusts (eg. These areas only become hazardous in case of an accident or some unusual operating condition. Please read Google Privacy & Terms for more information about how you can control adserving and the information collected. 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. Note to paragraph (g)(5)(ii)(C) of this section: The National Electrical Code, NFPA 70, contains guidelines for determining the type and design of equipment and installations that will meet this provision. In instances of areas within the same facility classified separately, Class I, Zone 2 locations may abut, but not overlap, Class I, Division 2 locations. Other ignition sources can also be present, like static electricity. Which system is preferred depends on the users preference, how the areas are classified, and the wiring system used. The Zone system for classifying hazardous locations used in NFPA 70 NEC, IEC 60079, and the Canadian Electrical Code indicates the level of probability that a flammable concentration of a hazardous substance may be present. The Raytec SPARTAN range includes dedicated luminaires for both Zone 1 and Zone 2 areas as well as industrial applications. . 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. according to ISO standard 80079 series. 10/1/20 Article 505 National Electrical Code (NEC), Article 506 National Electrical Code (NEC). No other aspect of safety receives more attention in the form of codes and standards. For example the EI 15 and API 500/505 describe specific installations and several conditions for the oil and gas industry. Equipment of the nonheat-producing type, such as junction boxes, conduit, and fittings, and equipment of the heat-producing type having a maximum temperature not more than 100 C (212 F) need not have a marked operating temperature or temperature range; Electric equipment suitable for ambient temperatures exceeding 40 C (104 F) shall be marked with both the maximum ambient temperature and the operating temperature or temperature range at that ambient temperature; and. Within the European Union, these are defined by IEC/EN standards (IEC/EN 60079-10-1 or 2) as directed by ATEX. The lower explosion limit of a substance is the lowest concentration (in volume percentages for gases and liquids) of a gas or a vapor in air of producing a flash of fire in the presence of an ignition source. Electronic equipment, including lighting, needs to be purpose designed for use in hazardous areas to prevent a spark occurring and igniting any flammable substances. Equipment can be designed or modified for safe operation in hazardous locations. 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. Comparison of Zone 2 and Division 2 TABLE 1 - AREA CLASSIFICATIONS Division 1: Where ignitable concentrations can exist all of the time or some . There are two systems in place, including the traditional North American Division system as well as the alternative Zone system. . 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. Sources of Australia and New Zealand use the same IEC-60079 standards (adopted as AS/NZS60079), however the CE mark is not required. Zone 1 - A place in which an explosive atmosphere is likely to occur in normal operation occasionally One of the hazards of working with flammable substances is an explosion, mostly hand in hand with fire. NFPA 70 NEC uses the familiar Class/Division system and has added an Americanized version of the International Electrochemical Commissions (IEC) IEC Zone system which maintains the NEC wiring methods and protection techniques. | For Gas/Vapor this would be Zone 0. When the concentration of gas or vapor is above the UEL the gas mixture is too rich to burn. September 2020 Two possible classifications are described, in Section 18 (Zones), and Appendix J (Divisions). These generally give rise to areas classied as Zones 0, 1, and 2 respectively. July 2019 Where pyrophoric materials are the only materials used or handled, these locations need not be classified. Standards and regulations exist to identify such locations, classify the hazards, and design equipment for safe use in such locations. The inductance of the signal bell coils, combined with breaking of contacts by exposed metal surfaces, resulted in sparks, causing an explosion. Zone 2 hazardous areas are typically storage areas but can also be process areas. In some cases, the hazardous atmosphere is present all the time, or for long periods. This blog post will focus on the different hazardous location classifications and well follow up with another that discusses how equipment can be constructed and certified for use in these environments. This is exactly defined as the limiting concentration of oxygen below which combustion is not possible, independent of the concentration of fuel. - Zone 0: An area where an explosive gas-air mixture is continuously present or present for long time (continuous hazard, whose estimated duration is higher than 1000 hours/year) - Zone 1: An area where an explosive gas-air mixture is likely to occur during normal . >> NEC: Class I, Division 2, Group D. | IEC: Zone 2, Group II. Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 7, Safety Systems, Hazardous Areas and Fire, June 2013, Lloyd's Register, Global Standards. Only emails and answers are saved in our archive. It is obvious to use those standards within these industries. 1: As a guide in determining when flammable gases or vapors are present continuously or for long periods of time, refer to ANSI/API RP 505-2018, Informational Note No. THE PRODUCTS YOU NEED, Also included in the marking are the manufacturers name or trademark and address, the apparatus type, name and serial number, year of manufacture and any special conditions of use. As world trade becomes more globalized, international standards are slowly converging, so that a wider range of acceptable techniques can be approved by national regulatory agencies. An area where combustible dusts or ignitable fibers and flyings are likely to occur under normal operating conditions. For more detailed assessments or for situations where no specific industry standards are available , like the chemical or pharmaceutical sector and also specific installation for oil and gas industries, a more quantitative approach can be used. . API RP 505, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Zone 0, Zone 1, and Zone 2 (as incorporated by reference in 250.198). less than 0.45 mm or MIC ratio is less than 0.40. The a subdivisions have the most stringent safety requirements, taking into account more than one independent component faults simultaneously. Zone 1 is an area in which an explosive atmosphere is likely to occur occasionally in normal operation. In general, all types of equipment installed within the hazardous area shall be . . Refrigerated November 2020 Offshore Workshop Container Identifying Zone 0, Zone 1, and Zone 2 Hazardous Areas. So yes, it is important to choose the right model and always wonder what am I assessing?. Get more great content like this sent to your inbox. This article is not a substitute for review of current applicable government regulations, industry standards, or other standards specific to your business and/or activities and should not be construed as legal advice or opinion. Hazardous areas are those defined as areas of potential explosion risk due to the presence of flammable gas or vapor. In Northerm America, instead of the zone classification system, the Class/Division system is used. may exist under normal or abnormal conditions because of the presence of flammable gases or vapors, combustible dusts or ignitable fibers or flyings. February 2021 NEC 2 Divisions (Div 1 2) Division I Comprising of Area Same as Zone 0 1. Groups A, B, C, and D are for gases (Class I only). Classification of locations, testing and listing of equipment, and inspection of installation, is typically overseen by governmental bodies. At least two British mine explosions were attributed to an electric bell signal system. When the concentration of gas or vapor is beneath the LEL the gas mixture is too lean to burn. June 2019 THE CURRENT STANDARD . The upper explosion limit of a substance is the highest concentration (in volume percentages for gases and liquids) of a gas or a vapor in air capable of producing a flash of fire in the presence of an ignition source. This was accompanied by electrically-initiated explosions of flammable gas such as fire damp (methane) and suspended coal dust. A major safety concern in all workplaces is the occurrence of fires and explosions. 286 natural gas explosions per year in the U.S. causing substantial damage, severe injury or loss of lives. Hazardous Areas - North America Classification, international method of area classification, Protection Techniques for Hazardous Areas - North America, Hazardous because combustible or conductive, Atmosphere containing combustible metal dusts, including. . Since the changes to the code, hazardous locations with gases or vapors (Class I) present can be reclassified as Zone 0, 1 or 2. Zone 1 is an area in which an explosive atmosphere is likely to occur occasionally in normal operation. Informational Note No. TLS OFFSHORE CONTAINER hazardous areas as the following: An area where a potential hazard (e.g., a fire, an explosion, etc.) Which Standards to use for Hazardous Area Classification. February 2023 Equipment used in hazardous area must comply to certain Ex standards. Areas with possible fire or explosion risks due to explosive atmospheres and/or mixtures - are called hazardous (or classified) locations or areas. Note to paragraph (g)(4) of this section: Low ambient conditions require special consideration. lk) are places where fire or explosion hazards may exist. However, at low ambient temperatures, flammable concentrations of vapors may not exist in a location classified Class I, Zone 0, 1, or 2 at normal ambient temperature. Increased safety "e" -- This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved.
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