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). (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. March 2022 Atmospheres containing ethylene, propylene oxide, ethylene oxide, butadiene, cyclopropane, ethyl ether, or gases and vapors of equivalent hazard. Division 2 is equivalent to Zone 2, while Division 1 is either Zone 0 or 1. 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. 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. 2: For Group IIIC combustible dusts or metal combustible fibers/flyings, there shall only be Zone 20 or 21 locations. Encapsulation "m" -- This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved. If equipment has been approved for use in a Division 1 hazardous location, it can be used in a Division 2 hazardous location, providing it is in the same class and group. NEC has created an Americanized version of the IEC/CENELEC Zone system in a stand-alone article (Article 505). 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. In the US, the National Electrical Manufacturers Association (NEMA) defines standards for enclosure types for a variety of applications. In the United Kingdom, Sira and Baseefa are the most well known such bodies. These generally give rise to areas classied as Zones 0, 1, and 2 respectively. Division II Comprising of Area Same as Zone 2. The term equipment is applied both for fixed equipment and mobile equipment that are operated in such area. Dry Container 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. Area's are divided into zones. When the concentration of methane is beneath the LEL, an explosion cannot occur, even when an ignition source is present. Informational Note No. Category 1 equipment may be used in zone 0, zone 1 or zone 2 areas. 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. The autoignition temperature is the lowest temperature at which the substance will ignite without an additional heat or ignition source (at atmospheric pressure). These are typically process areas where gases are more likely to be present. Industrial electrical equipment for hazardous area has to conform to appropriate parts of standard: IEC-60079 for gas hazards, and IEC-61241 for dust hazards. We don't collect information from our users. 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. ESS Container In this system, two bare wires were run along the length of a drift, and any miner desiring to signal the surface would momentarily touch the wires to each other or bridge the wires with a metal tool. 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. Group define the type of hazardous material and (partly) the location of the surrounding atmosphere. Zone 0, 1, and 2 locations shall include those specified in 505.5 (B) (1), (B) (2), and (B) (3). No. 29 CFR 1910.399 Definitions Applicable to Subpart S International Electrotechnical Committee (IEC) Hazardous Area Classification. In ambient conditions it is assured that oxygen is always present and thus not a factor that has to be incorporated within the hazardous area assessment. Class 1/Div 2 ATEX Zone 2 Computers. Refer to Fig.3 which shows the hazardous area zone classification based on hazardous gas release grade. Comparison of Zone 2 and Division 2 TABLE 1 - AREA CLASSIFICATIONS Division 1: Where ignitable concentrations can exist all of the time or some . Equipment marked as suitable for Group IIC is also suitable for IIB and IIA. AddThis use cookies for handling links to social media. 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. Classification of Hazardous Areas 0 100 200 300 400 500 600 T1 >450C T2 >300C 450C T3 >200C 300C T4 >135C 200C . Non-hazardous or ordinary locations. The a subdivisions have the most stringent safety requirements, taking into account more than one independent component faults simultaneously. Increased safety "e" -- This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved. In Europe and the rest of the world - but also more and more in North America - the Zone system is used. Various regulations use terms such as class, division, zone, and group to differentiate the various hazards. Hazardous area equipment is categorized into category-1 for Zone 0 or Zone 20, category-2 for Zone 1 or Zone 21, and category-3 for Zone 2 or Zone 22. For gases, vapours and mists the zone classifications are recognised as Zone 0, Zone 1 and Zone 2 areas. Equipment that is listed for a Zone 1 location may be installed in a Zone 2 location of the same gas or vapor. Zone 0 is reserved for those areas continuously hazardous (e.g., inside a vented fuel tank), so other Division 1 areas would be classified as Zone 1. The substance referred to by classhas a high probability of producing an explosive or ignitable mixture due to it being present continuously, intermittently, or periodically or fromthe equipment itself under normal operating conditions. Equipment should be tested to ensure that it does not exceed 80%[according to whom?] Ignition sources can be divided in 13 categories (acc. Hazardous area classification. 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). Please read Google Privacy & Terms for more information about how you can control adserving and the information collected. 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." d : HA - ha ea OA - oa Area classification - Divisions vs. zones Continuous hazard Intermittent hazard Hazard under abnormal conditions Zone 0 Zone 1 Zone 2 Division 1 Division 1 Division 2 Hazardous locations - CEC classifications Class I Determined to be none of the above. Iso Container SEWAGE TREATMENT Ex s is a coding referenced in IEC 60079-0. . CUTTING SKIPS In other cases, the atmosphere is normally non-hazardous, but a dangerous concentration can be reasonably foreseensuch as operator error or equipment failure. 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 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). Whenever you are filling up your tank you are standing in a Zone 1 hazardous area. 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. This is because Zone 0 usually classifies areas for gas storage or containment, and any lighting required would be used on a small and portable basis for visual inspection, e.g. Zone 1 - A place in which an explosive atmosphere is likely to occur in normal operation occasionally Is intended for us in Zone 2 (gases) or Zone 22 (dusts). Category 3 equipment may only be used in zone 2 areas. A60 Group defines the type of the hazardous material in the surrounding atmosphere. 5mm -750C Electrical Resistivity. hazardous areas as the following: An area where a potential hazard (e.g., a fire, an explosion, etc.) 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. Lets take a look at what defines each zone. 5: For further information on ventilation, see NFPA 30-2018, Informational Note No. ADNOC Informational Note: For further information regarding classification and ventilation of areas involving closed-circuit ammonia refrigeration systems, see ANSI/IIAR 2-2014. Two possible classifications are described, in Section 18 (Zones), and Appendix J (Divisions). the inside of tank truck or the interior of a dust filter). . >> For Gas/Vapor this would be Zone 0. 10: For information on electrical resistance trace heating for hazardous (classified), Informational Note No. An area where combustible dusts or ignitable fibers and flyings are not likely to occur under normal operating conditions and do so only for a short period of time. The following content is only related to flammable substances and not to pyrotechnic substances or other instable substances, among those who can decompose. No representation is made that the information or references are complete or remain current. Zone 0 - Explosive atmospheres present continuously long periods or frequently. It uses the familiar Class/Division system and adapts the IEC/CENELEC Zones into it while maintaining NEC wiring methods and . Have a think about it next time youre filling up! Laboratory Container This is exactly defined as the limiting concentration of oxygen below which combustion is not possible, independent of the concentration of fuel. Zone type (0/1/2/ 20/21/ 22) Zone extent. class correct, Motors, lighting, junction boxes, electronics, Equipment is very robust and components are made to a high quality, Equipment components are completely submerged in oil, Equipment components are completely covered with a layer of sand, powder or quartz, Equipment components of the equipment are usually encased in a resin type material. Beside sufficient fuel, also sufficient oxygen is needed for combustion of the mixture. Category 2 equipment may be used in zone 1 or zone 2 areas. November 2021 Other ignition sources can also be present, like static electricity. coal and charcoal), Group G Nonconductive dusts (eg. All rights reserved. 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. Gas a. National Electrical Code (NEC) and the 1998 Canadian Electrical Code (CEC) now recognize the use of the Zone system for classification of hazardous areas. There are several ways of how to perform hazardous area classification, all described in several standards or codes of practise. The NEC Zone system was created to harmonize with IEC classification system, and therefore reduce the complexity of management. Please read AddThis Privacy for more information. All emergency versions, whether Zone 1 or Zone 2 can also be easily visually identified by their red end cap, encapsulating the emergency battery back-up. 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. area in which an explosive gas atmosphere is likely to occur occasionally in normal operation. 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. Outside of the United States, the IEC uses two different classifications: Gas & Vapor (Zones 0, 1, or 2) Dust (Zones 20, 21, or 22) Step 2: The next step is to determine how often the hazardous substance (s) is/are present. The Zone system has wider use in the chemical and petrochemical industries. 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. Within a working area or installation an ignition can be created by many factors. An area where combustible dusts or ignitable fibers and flyings are present continuously or for long periods of time. Hazardous Area Classifications D103222X012 Product Bulletin 9.2:001 September 2019. Equipment approved for use in Class I hazardous locations cannot be used in Class II hazardous locations. Hazardous Area Classifications D103222X012 Product Bulletin 9.2:001 . 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. These areas are in North America (United States and Canada) historically classified with the Class/Division system. Exception No. This can be achieved by blanketing with nitrogen or carbondioxide. Group defines thetypeof hazardous material and partly thelocationof the surrounding atmosphere . As a result, all hazardous area equipment must be designed with hazardous area zone classifications in mind, as the zone governs the level of protection and precaution required. 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. Comments. And safety must be guaranteed in the case of two faults occurring independently of each other. 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. Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications! Each room, section, or area shall be considered individually in determining its classification. And there are three corresponding zones for dust: Zone 20, Zone 21 and Zone 22. Article 505 National Electrical Code (NEC), Article 506 National Electrical Code (NEC). July 2021 Ways to ensure this level of safety are non-arcing design and limitation of the temperature of the equipment. of 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". lk) are places where fire or explosion hazards may exist. Only emails and answers are saved in our archive. Cookies are only used in the browser to improve user experience. The Regulations define 3 zones that can exist within a hazardous area: Zone 0 - A place in which an explosive atmosphere is present continuously or for long periods. In the US, the independent National Fire Protection Association (NFPA) publishes several relevant standards, and they are often adopted by government agencies. 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 . Upon detection, appropriate action is automatically taken, such as removing power, or providing notification. Class I Zone 2 Hazardous Areas. Temperature classification, except for intrinsically safe apparatus. Flammable liquids with a high flash point are less hazardous than liquids Hazardous areas are defined as: " Zones " under worldwide IEC standards (and their local versions, such as ATEX in Europe) " Divisions " under North American NEC standards. Zone 0: flammable atmosphere highly likely to be present - may be present for long periods or even continuously . Container Standards This process is called hazardous area classification. The equipment housing may be sealed to prevent entry of flammable gas or dust into the interior. Group is divided in three groups where Group I is reserved for mining locations. |MWD/LWD Cabin 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. Carbon monoxide, ether, hydrogen sulfide, . A list must be drawn up of every explosive material that is on the refinery or chemical complex and included in the site plan of the classified areas. 1.1 Scope. Groups E, F, and G are for dusts and flyings (Class II or III). 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. 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. April 2021 Although every application is different, for the ease of monitoring and specification each hazardous area is classified as a particular level or zone. The choice of which standard to use for the hazardous area classification is something which is very important. September 2022 SPARTANs Zone 1 part code begins SPX, Zone 2 SPZ and industrial products having a SPI prefix. Atmosphere containing a flammable gas, a flammable liquid produced vapor or a combustible liquid-produced vapor whose MESG is greater than 0.75 mm or MIC ratio is greater than 0.40 and less than 0.80 - such as carbon monoxide, ether, hydrogen sulfide, morphline, cyclopropane, ethyl, isoprene, acetaldhyde and ethylene or gases of equivalent hazard. The definition of the hazardous area zones represent the likelihood of hazardous gas, dust or other hazards being present in a working area. 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. If you want to promote your products or services in the Engineering ToolBox - please use Google Adwords. Atmosphere containing carbonaceous dusts, Atmosphere containing combustible dust not included in Group E & F - such as. may exist under normal or abnormal conditions because of the presence of flammable gases or vapors, combustible dusts or ignitable fibers or flyings. December 2022 National Electric Code 2020 edition National Fire Protection Association. 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). See below for further details: Division system sample marking 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. July 2022 Analysers, motors, control boxes, computers, Any arcs or sparks in this equipment has insufficient energy (heat) to ignite a vapour. October 2018 October 2022 Dn 1 - a Ce e . With the advent of electric power, electricity was introduced into coal mines for signaling, illumination, and motors. Zones. All equipment in Division 1 areas must have an approval label, but certain materials, such as rigid metallic conduit, does not have a specific label indicating the Cl./Div.1 suitability and their listing as approved method of installation in the NEC serves as the permission.