Pit will be considered as Zone 1. Equipment marked as suitable for IIB is also suitable for IIA but NOT for IIC. 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. 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. Equipment construction is such that it can withstand an internal explosion and provide relief of the external pressure via flamegap(s) such as the labyrinth created by threaded fittings or machined flanges. 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. Terminology for both hazards and protective measures can vary. 29 CFR 1910.307 Hazardous (classified) Locations Category 3 equipment may only be used in zone 2 areas. No long-term contract. ignitable concentrations of dust, fibers, or flyings are present for long periods of time, ignitable concentrations of dust, fibers, or flyings are likely to exist under normal conditions, ignitable concentrations of dust, fibers, or flyings unlikely to exist under normal conditions, Metal dusts, such as magnesium (Division 1 only), Carbonaceous dusts, such as carbon & charcoal, Non-conductive dusts, such as flour, grain, wood & plastic, Ignitible fibers/flyings, such as cotton lint, flax & rayon, Ignitible fibers or flyings, such as cotton lint, flax & rayon. This is an important factor in the classification of hazardous areas. An area where combustible dusts or ignitable fibers and flyings are likely to occur under normal operating conditions. gas, vapours, mists and dusts). Specific types of protection being used will also be marked. Equipment in this category is intended for use in Zone 0 areas (gases) or Zone 20 (dusts), and must ensure a very high level of protection (i.e. A hazardous area can be defined as any location where there is risk of an explosion. A: No. A Zone defines the general nature - if it is a gas or dust - and the probability of hazardous material being present in an ignitable concentration in the surrounding atmosphere. So a zone 0 is the most hazardous zone and a zone 2 is a less hazardous zone. 5: For further information on ventilation, see NFPA 30-2018, Informational Note No. area in which an explosive gas atmosphere is present continuously, or for long periods, or frequently (more than 10% of the time). | For Gas/Vapor this would be Zone 0. The NEC Zone system was created to harmonize with IEC classification system, and therefore reduce the complexity of management. Standards for electrical installations have been established and are governed by a variety of organizations throughout the world to ensure safe electrical systems in hazardous locations. Zone 2 - Explosive atmospheres are unlikely to occur or present only infrequently and for a short period only. When the concentration of methane is beneath the LEL, an explosion cannot occur, even when an ignition source is present. Class defines the general nature (or properties) of the hazardous material in the surrounding atmosphere. Well recognized and clear IEC Standard IEC 60079-10-2:2015 Hazardous Area Classification for explosive dusts Significant influence on spending's for safety . according to ISO standard 80079 series. Hazardous areas are classified into 3 zones based upon the frequency of the occurrence and duration of an explosive gas atmosphere, as follows: Zone 0 Area in which an explosive gas atmosphere is present continuously or for long periods or frequently. 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). It uses the familiar Class/Division system and adapts the IEC/CENELEC Zones into it while maintaining NEC wiring methods and . Offshore Workshop Container Powder Filling "q" -- This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved. 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. Ignition sources can be divided in 13 categories (acc. NFPA 70 NEC establishes area classifications based on Classes, Divisions and Groups that when combined delineate the hazardous conditions of a specific area. Zone 0Ignitable concentrations of flammable gases or vapors which are present continuously or for long periods of time. The design of the equipment must ensure protection, even in the event of rare incidents relating to the equipment. November 2020 ADNOC Unlike ATEX which uses numbers to define the safety "Category" of equipment, namely (1,2 3), the IEC continued to utilise the method used for defining the safe levels of intrinsic safety namely "a" for zone 0, "b" for zone 1 and "c" for zone 2 and apply this Equipment Level of Protection to all equipment for use in hazardous areas since 2009. D8.1.3 Hazardous areas are subdivided into Zones 0,1 or 2, the definitions of each cate-gory being as follows: Zone 0 an area in which an explosive gas-air mixture is continuously present or present for long periods. Zone 0, 1, and 2 locations are those in which flammable gases or vapors are or may be present in the air in quantities sufficient to produce explosive or ignitible mixtures. 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. When equipment must be placed in a hazardous location, it can be designed to reduce the risk of fire or explosion. For equipment with metric threaded entries, such entries shall be identified as being metric, or listed adaptors to permit connection to conduit of NPT-threaded fittings shall be provided with the equipment. Explosion Hazardous Areas are divided into zones according to risk probabilities. This was accompanied by electrically-initiated explosions of flammable gas such as fire damp (methane) and suspended coal dust. SIGN UP FOR EMAILGet more great content in your inbox. 1910.307 (g) (2) Class defines the type of explosive or ignitable substances which are present in the atmosphere. Electrical equipment installed in such locations can provide an ignition source, due to electrical arcing, or high temperatures. Only emails and answers are saved in our archive. Choose the right method for Hazardous Area Classification! >> For Gas Vapor this would be Zone 1. 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 Dust this would be Zone 22. This process is called hazardous area classification. The temperature classification on the electrical equipment label will be one of the following (in degree Celsius): The above table shows that the surface temperature of a piece of electrical equipment with a temperature classification of T3 will not rise above 200C. Category 1 equipment may be used in zone 0, zone 1 or zone 2 areas. September 2021 Since the changes to the code, hazardous locations with gases or vapors (Class I) present can be reclassified as Zone 0, 1 or 2. Atmospheres containing non-conductive dust. Temporary Refuge (TR) Shelter 1: As a guide to classification of Zone 22 locations, refer to ANSI/ISA 60079-10-2 (12.10.05)-2013, Explosive Atmospheres Part 10-2: Classification of areas Combustible dust atmospheres. 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. The definition of Zone 2 is a hazardous area classified as an atmosphere where a mixture of air and flammable substances in the form of gas, vapour or mist is not likely to occur in normal operation, but if it does occur, will persist for a short period only. August 2021 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. 1: For examples of area classification drawings, see ANSI/API RP 505-2018, Informational Note No. The Zones are based on how often the hazard is present rather than upon normal versus abnormal conditions. 2: This classification includes, Informational Note No. of the autoignition temperature of the hazardous atmosphere. In recent years also the EPL is specified for several kinds of protection. area in which an explosive gas atmosphere is likely to occur occasionally in normal operation. Some of our calculators and applications let you save application data to your local computer. Area ClassificationThe max surface temp. 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. For example, within the U.K. in the Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) and in the U.S. in the Occupational Safety and Health Act of 1970 (OSHA). National Electrical Code (NEC) and the 1998 Canadian Electrical Code (CEC) now recognize the use of the Zone system for classification of hazardous areas. Arc-producing elements can be isolated from the atmosphere, by encapsulation in, Heat-producing elements can be designed to limit their maximum temperature below the. Often an area classification plan view is provided to identify equipment ratings and installation techniques to be used for each classified area. Ex Zone. Type of protection "n" is further subdivided into nA, nC, and nR. 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). In Europe and the rest of the world - but also more and more in North America - the Zone system is used. May 2022 Such properties include flame temperature, minimum ignition energy, upper and lower explosive limits, and molecular weight. Zone 1 (unless separated by a fire wall)P.G.Sreejith, Kerala. Controls can be fitted to detect dangerous concentrations of hazardous gas, or failure of countermeasures. These ways of protection are specified in detail within several IEC standards (IEC 60079 series) for electrical equipment. That flammable gas or vapor . Click on the zone to learn more about the classification according to IEC 60079-10 standards. 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. Group is divided in three groups where Group I is reserved for mining locations. less than 0.45 mm or MIC ratio is less than 0.40. Which Standards to use for Hazardous Area Classification. Australia and New Zealand use the same IEC-60079 standards (adopted as AS/NZS60079), however the CE mark is not required. Temperature classification, except for intrinsically safe apparatus. This can be achieved by blanketing with nitrogen or carbondioxide. A material may have a relatively low autoignition temperature yet if its flash-point is above the ambient temperature, then the area may not need to be classified. Each room, section, or area shall be considered individually in determining its classification. Comments. October 2019 Read more in our blogWhich Standards to use for Hazardous Area Classification. Group C materials have a MESG less than 0.75mm and a MIC ratio less than 0.80 (but greater than 0.40, which would put it in Group B.) Encapsulation "m" -- This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved. Groups E, F, and G are for dusts and flyings (Class II or III). 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. WATER TIGHTNESS The autoignition temperature is the lowest temperature at which the substance will ignite without an additional heat or ignition source (at atmospheric pressure). 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. Zones compares to classes and divisions in the Class/Division system. Zones 0, 1 and 2: Atmospheres with explosive gases and vapours (AS2380; AS/NZS/IEC 60079) Zone 0 Area The definition according to IEC60079-10-1 is "an area in which an explosive gas atmosphere is present continuously or for long periods or frequently". . NFPA 70 NEC Zone Classification System The Zone Classification System is offered as an alternative to the Class and Division system. The groups also indicate how much energy is required to ignite the material by energy or thermal effects, with IIA requiring the most energy and IIC the least for zone system gas groups. 1: The term "Class I" was originally included as a prefix to, Informational Note No. There are four zones in the IEC classification system: Zone 0: An area in which an explosive atmosphere is present continuously or for long periods. See Figure S-1 for an explanation of this marking. Although OSHA does not provide a definition of group classifications in 29 CFR 1910.307 or 399 they do provide a note under 29 CFR 1910.307(c)(1) that states: NFPA 70, the National Electrical Code, lists or defines hazardous gases, vapors, and dusts by Groups characterized by their ignitable or combustible properties. To meet OSHAs marking requirement, the marking must include the hazardous group the equipment is approved to operate in. 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. These are typically process areas where gases are more likely to be present. Zone 1 if gas group & temp. Informational Note No. The Hazardous Area Classification presents in this guide is based on the following items as reference: API: API RP 505 Recommended Practice for Classification of Locations for Electrical. Zone 1 2. These areas are classified solely for the purpose of ensuring the safe and proper specification and installation of electrical/electronic equipment. Zone 1 is an area in which an explosive atmosphere is likely to occur occasionally in normal operation. CLASSIFIED LOCATIONS: AREA CLASSIFICATION: AREA CLASSES: AREA GROUPS: LOCATION AS PER DIVISIONS: DIVISION 1 - Class I, Division 1 hazardous locations are defined (as per NEC code Article 500) as follows: DIVISION 2 - Class I Division 2 Locations are as follows: Area Classification by ZONES: DEFINITIONS: HAZARDOUS LOCATIONS: November 2021 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. . Equipment in this category is intended for use in areas in which explosive atmospheres caused by gases, vapours, mists or air/dust mixtures are likely to occur occasionally. Zone 0, 1, and 2 locations shall include those specified in 505.5 (B) (1), (B) (2), and (B) (3). 2: For the requirements for electrical and electronic. An area where combustible dusts or ignitable fibers and flyings are present continuously or for long periods of time. ), Group F Carbon-based (eg. Temperature Control Zone 0 is an area in which an explosive atmosphere is present continuously for long periods of time or will frequently occur. 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". Cookies are only used in the browser to improve user experience. Intrinsic safety designs equipment to operate using minimal energy, insufficient to cause ignition. The surface of a high pressure steam pipe may be above the autoignition temperature of some fuel-air mixtures. This paper will discuss and review the current approaches and solutions of dealing with these HSE concerns, especially with the involvement of hazardous and potentially flammable and explosive chemicals. You will find this equipment in paint factories, a warehouse or around a bag dump station. The Raytec SPARTAN range includes dedicated luminaires for both Zone 1 and Zone 2 areas as well as industrial applications. ". 41 gas explosions per year occur within the UK and app. Guidance on assessment of hazards is given in NFPA497 (explosive gas) and NFPA499 (dust). (Hazardous Area Classification) . The flash point determines if an area needs to be classified. It is essential to know which zone you are working in, so that you can specify the most appropriate equipment. The colour of the luminaire body indicates the level of protection. The four steps involved in hazardous area classification are: Determine the type of hazard or "class" that might be presentcombustible gas (Class I), combustible dust (Class II), or fibers (Class III). Identifying Zone 0, Zone 1, and Zone 2 Hazardous Areas. Photo 2. Adapters shall be used for connection to conduit or NPT-threaded fittings. Hazardous Area Classification, Gas Vapours and Dust Groups, Temperature Class | Simple Science Simple Science 8.81K subscribers Join Subscribe 28K views 2 years ago This video explains. Such areas include a residence or office where the only risk of a release of explosive or flammable gas would be such things as the propellant in an aerosol spray. 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. Zone defines the general nature - if it is a gas or dust - and the probability of hazardous material being present in an ignitable concentration in the surrounding atmosphere. Explosion protection must be ensured during normal operation. Many items of EEx rated equipment will employ more than one method of protection in different components of the apparatus. Zones 1 or 2. CUTTING SKIPS Is intended for us in Zone 2 (gases) or Zone 22 (dusts). There are two systems in place, including the traditional North American Division system as well as the alternative Zone system. This leads to a lot of the confusion in the global marketplace because certifying equipment to these different systems can be time consuming and expensive, so many companies may only certify to one or the other. Equipment shall be approved not only for the class of location, but also for the ignitable or combustible properties of the specific gas, vapor, dust, or fiber that will be present. RP 505 is referred to as the zone system. [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. Have a think about it next time youre filling up! Type of protection "n" -- This protection technique is permitted for equipment in the Class I, Zone 2 locations for which it is approved. Hazardous locations can also be described as those locations where electrical equipment Atmospheres containing combustible flyings. October 2020 September 2018 9: For additional information concerning the installation of, Informational Note No. Enclosures can be pressurized with clean air or inert gas, displacing any hazardous substance. A60 11: For information on electric skin effect trace heating for hazardous (classified), Informational Note No. Zone 0 describes an area in which a combustible gas will be present continuously while zone 20 describes an area in which combustible dust will be present continuously (the '2' in 'zone 20' indicates dust as opposed to gas). The American Petroleum Institute publishes analogous standards in RP500 andRP505. Equipment approved for Class I, Division 1 or Class 1, Division 2 shall, in addition to being marked in accordance with (c)(2)(ii), be marked with the following: Class I, Zone 1 or Class I, Zone 2 (as applicable); Applicable gas classification groups; and. Since this fuel can only combust in the presence of oxygen, enough oxygen must be available for the rapid combustion to take place. That is why the use of mobile phones on petrol forecourts are banned. 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. Class 1/Div 2 ATEX Zone 2 Computers. TLS OFFSHORE CONTAINER December 2021 Increased safety "e" -- This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved. The housing may be strong enough to contain and cool any combustion gases produced internally. Class I hazardous locations are identified by zones as follows: * Zone 0 a location in which explosive gas atmospheres are present continuously or for long periods of time. [1] NEC article 500 describes the NEC Division classification system, while articles 505 and 506 describe the NEC Zone classification system. In the US, the independent National Fire Protection Association (NFPA) publishes several relevant standards, and they are often adopted by government agencies. 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. October 2021 2: Through the exercise of ingenuity in the layout of electrical installations for hazardous (classified), Refrigerant machinery rooms that contain ammonia refrigeration systems and are equipped with adequate mechanical ventilation that operates continuously or is initiated by a detection system at a concentration not exceeding 150 ppm shall be permitted to be classified as "unclassified". The minimum concentration of oxygen, necessary for the combustion to take place, is called the Limiting Oxygen Concentration. PROCESS OF CONTAINER January 2022 In order to understand hazardous area classification it is important to understand which factors contribute to the occurrence of an explosion. 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). June 2019 All areas in the facility that are not Zone 0, Zone 1, or Zone 2 are considered unclassified. Zone 0 Zone 1 Zone 2 Fluid Occurrence of explosive atmosphere Gas mixtures Dust mixtures Not likely to occur or only for short period Zone 2 Zone 22 . 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. Refrigerated Container 2: Where gas detection, Informational Note No. In the US, the National Electrical Manufacturers Association (NEMA) defines standards for enclosure types for a variety of applications. FEA Within the European Union, these are defined by IEC/EN standards (IEC/EN 60079-10-1 or 2) as directed by ATEX. Each chemical gas or vapour used in industry is classified into a gas group. 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. * Zone 2 a . 4: For further information on protection against static electricity and lightning hazards in hazardous (classified). 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. 2: This classification usually includes, (B) Special Occupancies, Zone 0, 1, and 2 Locations, Article 505 Special Occupancies, Zone 0, 1, and 2 Locations, (B) Special Occupancies, Class I, Zone 0, 1, and 2 Locations, National Electrical Code 2020 of Illinois, National Electrical Code 2017 of Illinois, Ignitible concentrations of flammable gases or vapors are present continuously, Ignitible concentrations of flammable gases or vapors are present for long periods of time, In which ignitible concentrations of flammable gases or vapors are likely to exist under normal operating conditions; or, In which ignitible concentrations of flammable gases or vapors may exist frequently because of repair or maintenance operations or because of leakage; or, In which ignitible concentrations of flammable gases or vapors are not likely to occur in normal operation and, if they do occur, will exist only for a short period; or, In which volatile flammable liquids, flammable gases, or flammable vapors are handled, processed, or used but in which the liquids, gases, or vapors normally are confined within closed containers of closed systems from which they can escape, only as a result of accidental rupture or breakdown of the containers or system, or as a result of the abnormal operation of the, In which ignitible concentrations of flammable gases or vapors normally are prevented by positive mechanical ventilation but which may become hazardous as a result of failure or abnormal operation of the ventilation. LIFTING TEST December 2013, All These generally give rise to areas classied as Zones 0, 1, and 2 respectively. In other cases, the atmosphere is normally non-hazardous, but a dangerous concentration can be reasonably foreseensuch as operator error or equipment failure. Atmosphere containing carbonaceous dusts, Atmosphere containing combustible dust not included in Group E & F - such as. Division 2 is equivalent to Zone 2, while Division 1 is either Zone 0 or 1. Category 2 equipment may be used in zone 1 or zone 2 areas. So the following conditions must be met for an explosion to occur: Represented by the following explosion triangle. 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 . 15 4. An explosion is a rapid expansion in volume associated with an extremely vigorous outward release of energy, usually with the generation of high temperatures and release of high-pressure gases (wikipedia (https://en.wikipedia.org/wiki/Explosion).
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