We will go deeper into ignition assessments in another blog. Conversely if the same material is heated and handled above its flash-point, the area must be classified for proper electrical system design, as it will then form an ignitable mixture.[5]. Ignitable concentrations of flammable gases or vapors which are present continuously or for long periods of time. Beside sufficient fuel, also sufficient oxygen is needed for combustion of the mixture. So it is quite obvious that explosions should be prevented as much as possible and still work has to be done to achieve this. In an industrial plant, such as a refinery or chemical plant, handling of large quantities of flammable liquids and gases creates a risk of exposure. 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. This temperature is used for classification for industry and technology applications.[6]. Equipment can be designed or modified for safe operation in hazardous locations. SIGN UP FOR EMAILGet more great content in your inbox. These ways of protection are specified in detail within several IEC standards (IEC 60079 series) for electrical equipment. The label will always list the class, division and may list the group and temperature code. February 2023 Zones 1 or 2. 10/1/20 Container Test September 2018 Arcing electrical equipment in unclassified . The prevention of explosions in working environments is in most countries regulated in national laws and directives. Division II Comprising of Area Same as Zone 2. Zone 2: An area in which an explosive atmosphere is not likely to occur in normal operation, but if it does . How to perform Hazardous Area Classification? 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. The temperature marking may not exceed the ignition temperature of the specific gas or vapor to be encountered. See Figure S-1 for an explanation of this marking. NEGATIVE PRESSURE The CE mark is complemented with the Ex mark: A yellow-filled hexagon with the Greek letters (epsilon chi), followed by the Group, Category, and, if Group II, G or D (gas or dust). IECEx Karandikar Certification Several protection strategies exist. The definition of the hazardous area zones represent the likelihood of hazardous gas, dust or other hazards being present in a working area. No other aspect of safety receives more attention in the form of codes and standards. CUTTING SKIPS 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. AddThis use cookies for handling links to social media. A: No. These areas only become hazardous in case of an accident or some unusual operating condition. But first, we must consider what is likely to cause an explosion in the first place. Comparisons between the two systems are not easily accomplished. Substances characterization Consequences . Determined to be none of the above. Recommendat ions. 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. . But beside electrical equipment also mechanical equipment must be Ex certified, e.g. Much early equipment having Ex s protection was designed with encapsulation and this has now been incorporated into IEC 60079-18 [Ex m]. For equipment provided with threaded entries for NPT threaded conduit or fittings, listed conduit, conduit fittings, or cable fittings shall be used. Hazardous areas are those defined as areas of potential explosion risk due to the presence of flammable gas or vapor. 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. 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. Entire Vapour space of storage tank. This is exactly defined as the limiting concentration of oxygen below which combustion is not possible, independent of the concentration of fuel. 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. . (Hazardous Area Classification) . 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". 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. Equipment provided with threaded entries for field wiring connection shall be installed in accordance with paragraph (g)(2)(iv)(A) or (g)(2)(iv)(B) of this section. Not only are hazardous areas classified by Class (nature of the hazardous material,) and Division . 3: Text that is followed by a reference in brackets has been extracted from NFPA 497-2017, All other applicable rules contained in this, Where the term "Class I" is used with respect to, Informational Note: The term "Class I" was originally included as a prefix to, All areas in industrial occupancies designated as hazardous (classified). That is why the use of mobile phones on petrol forecourts are banned. 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. In Northerm America, instead of the zone classification system, the Class/Division system is used. (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. Identifying Zone 0, Zone 1, and Zone 2 Hazardous Areas. 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. 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. 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. Type of protection "n" -- This protection technique is permitted for equipment in the Class I, Zone 2 locations for which it is approved. FEA September 2022 For dusts: Zone 20, Zone 21 and Zone 22. ADNOC Encapsulation "m" -- This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved. National Electric Code 2020 edition National Fire Protection Association. Oil Immersion "o" -- This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved. In order to understand hazardous area classification it is important to understand which factors contribute to the occurrence of an explosion. The relation between that system and de zone classification system is clarified within the following table (only for gases and liquids are displayed, not for dusts and fibers). 1.1.1 This recommended practice applies to those locations where flammable gases or vapors, flammable liquids, or combustible liquids are processed or handled; and where their release into the atmosphere could result in their ignition by electrical systems or equipment. Magnesium, Titanium), IIB Nonconductive dusts (eg. Flameproof "d" - This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved. Explosions can cause significant damage along with severe injury or worse loss of life. Note to paragraph (c)(2)(i) of this section: NFPA 70, the National Electrical Code, lists or defines hazardous gases, vapors, and dusts by "Groups" characterized by their ignitable or combustible properties. 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. 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. 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 Dust this would be Zone 22. Electrical equipment can and does cause fires and/or explosions in certain atmospheres. 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. The types of protection are subdivided into several sub classes, linked to EPL: ma and mb, px, py and pz, ia, ib and ic. 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. . POSITIVE PRESSURE What Are All Those Gadgets On A Multitool? Drop Test The Zone system of hazardous area classification, defines the probability of the hazardous material, gas, or dust, being present in sufficient quantities that can generate explosive or ignitable mixtures. An area where combustible dusts or ignitable fibers and flyings are present continuously or for long periods of time. The information contained in this article is intended for general information purposes only and is based on information available as of the initial date of publication. Pressurised Container A special standard for instrumentation is IEC/EN 60079-27, describing requirements for Fieldbus Intrinsically Safe Concept (FISCO) (zone 0, 1 or 2) (This special standard has been withdrawn, and has been partially replaced by: IEC/EN60079-11:2011 and IEC/EN60079-25:2010)[1], A special standard for instrumentation is IEC/EN 60079-27, describing requirements for Fieldbus Non-Incendive Concept (FNICO) (zone 2) (This special standard has been withdrawn, and has been partially replaced by: IEC/EN60079-11:2011 and IEC/EN60079-25:2010)[9]. Zone 2 - Explosive atmospheres are unlikely to occur or present only infrequently and for a short period only. Fundamentally, for an explosion to take place, flammable or explosive gases, vapours, mists or dusts will be present. Cookies are only used in the browser to improve user experience. 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. 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. Classification of locations, testing and listing of equipment, and inspection of installation, is typically overseen by governmental bodies. Electronic equipment, including lighting, needs to be purpose designed for use in hazardous areas to prevent a spark occurring and igniting any flammable substances. The use of EPL and ATEX Category directly is an alternative for "s" marking. The autoignition temperature is the lowest temperature at which the substance will ignite without an additional heat or ignition source (at atmospheric pressure). For methane this is shown in the following figure. Class I: hazardous because flammable gases or vapors are present in the air in quantities sufficient to produce explosive or ignitable mixtures: . WELDING INSPECTION February 2021 A spark or high heat must also be present. November 2019 NFPA 70 NEC Zone Classification System The Zone Classification System is offered as an alternative to the Class and Division system. Ex Zone. Purged and pressurized -- This protection technique is permitted for equipment in the Class I, Zone 1 or Zone 2 locations for which it is approved. 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 Equipment is placed into protection level categories according to manufacture method and suitability for different situations. 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. 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 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). 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. Offshore Accommodation Module February 2022 . Dust or other small particles suspended in air can explode. We don't collect information from our users. This article covers the requirements for the, Informational Note No. The Zones are based on how often the hazard is present rather than upon normal versus abnormal conditions. Equipment approved for use in Class I hazardous locations cannot be used in Class II hazardous locations. 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.
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