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. The Class/Division/Group system is based on Article 500 of the National Electrical Code (NEC) where. That is why the use of mobile phones on petrol forecourts are banned. 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. Australia and New Zealand use the same IEC-60079 standards (adopted as AS/NZS60079), however the CE mark is not required. 7: For further information on application of electrical, Informational Note No. Hazardous Environment Classifications: NEC vs IEC, IEC (International Electrotechnical Commission), Group E Metal dusts (eg. Accommodation Cabin For example, a Class 1, Div 1 area where Group A may be present would be defined as an area where flammable gases or vapors may be present under normal operating conditions. Beside sufficient fuel, also sufficient oxygen is needed for combustion of the mixture. 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. The design of the equipment must ensure protection, even in the event of rare incidents relating to the equipment. according to ISO standard 80079 series. The Zone system has wider use in the chemical and petrochemical industries. 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. 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). February 2023 of the autoignition temperature of the hazardous atmosphere. 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. Dust or other small particles suspended in air can explode. If equipment is marked, for example, Ex e II T4 then it is suitable for all subgroups IIA, IIB and IIC. March 2022 Hazardous locations can also be described as those locations where electrical equipment SEWAGE TREATMENT Hazardous area classification is a rigorous method of determining where an explosive environment may be present. January 2021 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. February 2021 Example - Hazardous Area Classification A room with a propane gas installation will typically be classified with the Class/Division system as: Class I, Division 2, Group D Zone system as: Zone 2, Group IIA 1910.307 - Hazardous (classified) locations. This rapid expansion of volume is caused by the combustion of a fuel, like e.g. 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. Ways to ensure this level of safety are non-arcing design and limitation of the temperature of the equipment. 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. National Electrical Code, NFPA 70, Chapter 5, Article 500, 29 CFR 1910 Subpart S, Electrical 1910.307, NFPA 497, "Classification of Gases, Vapors, and Dusts for Electrical Equipment in Hazardous Classified Locations", NFPA Handbook, "Electrical Installations in Hazardous Locations, " by P. J. Schram and M. W. Earley, NFPA 70E, Chapter 5, "Hazardous (Classified) Locations", ANSI/UL 913, "Intrinsically Safe Apparatus", NFPA 496, "Purged and Pressurized Enclosure for Electrical Equipment in Hazardous Locations. Offshore Living Quarter At least two British mine explosions were attributed to an electric bell signal system. April 2022 Atmospheres containing combustible flyings. International Electrotechnical Committee (IEC) Hazardous Area Classification. Then, the level of risk of an explosion is based on the frequency and duration of the occurrence of an explosive atmosphere. As to the classification, they are the same. Table 1. 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. The Zone system has three levels of hazard for gas or dust where the Division system has two. 0,1 or 2: II B: I: 1 or 2: C: Acetone Benzene Butane Hexane . This is exactly defined as the limiting concentration of oxygen below which combustion is not possible, independent of the concentration of fuel. Pressurised Container National Electrical Code (NEC) and the 1998 Canadian Electrical Code (CEC) now recognize the use of the Zone system for classification of hazardous areas. 4: For further information on protection against static electricity and lightning hazards in hazardous (classified). Zone Hazardous Location 2 Table of . POSITIVE PRESSURE This temperature is used for classification for industry and technology applications.[6]. 2: Where gas detection, Informational Note No. Which system is preferred depends on the users preference, how the areas are classified, and the wiring system used. Atmosphere containing carbonaceous dusts, Atmosphere containing combustible dust not included in Group E & F - such as. A potential few examples of this are: The air space inside a tank of petrol 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. This value of this LOC differs per substance and depends also on the inert gas for achieving a low oxygen concentration. THE PRODUCTS YOU NEED, 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". PROCESS OF CONTAINER Magnesium, Aluminum, Titanium etc. There are several ways of how to perform hazardous area classification, all described in several standards or codes of practise. 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. [3], Different explosive atmospheres have chemical properties that affect the likelihood and severity of an explosion. Zone 1 - Explosive atmospheres are likely to occur. October 2022 And safety must be guaranteed in the case of two faults occurring independently of each other. The most standards and codes of practise for Hazardous Area Classification describe typical installations and work environments and their hazardous areas. 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. 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. Where there is potential for an explosive atmosphere, special precautions are needed to prevent fires and explosions. Offshore Accommodation Module Methane has a LEL of 4,4 vol%. AddThis use cookies for handling links to social media. A light switch may cause a small, harmless spark when switched on or off. FEA August 2018 Both external and internal temperatures are taken into consideration. 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. 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. June 2020 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). Area Classification. a headlamp, rather than a dedicated fixed luminaire. 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. 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 three necessary components for an explosion to occur; This needs to be present in a relatively high quantity to produce an explosive mixture (e.g. Temperature Control What are 'Dark Factories,' and Do They Really Exist? A major safety concern in all workplaces is the occurrence of fires and explosions. There are three zones for gas: Zone 0, Zone 1 and Zone 2. . NEGATIVE PRESSURE Q: Can I use a piece of equipment approved for use in a Division 1 hazardous location in a Division 2 hazardous location? Some other standards have more quantitative methods which require more knowledge of the plant, an example is the IEC standard 60079-10-1. Entire Vapour space of storage tank. Zones 1 or 2. 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. Hazards in this group gas can be ignited very easily indeed. Laboratory Container Shown below is a summary of the applicable NEC Articles to reference to ensure the proper requirements are applied. Terminology for both hazards and protective measures can vary. No representation is made that the information or references are complete or remain current. We don't collect information from our users. 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. NFPA 70, the National Electrical Code (NEC), defines area classification and installation principles. Informational Note No. | For Dust this would be Zone 22. 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. Class defines the type of explosive or ignitable substances which are present in the atmosphere. Definition of hazardous area zones (AS/NZS 60079.10): Zone 0 Magnesium, Titanium), IIB Nonconductive dusts (eg. Photo 2. 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: Flammable atmosphere expected to be present inside the storage tank continuously, hence it has been classified as zone 0. Equipment approved for use in Class I hazardous locations cannot be used in Class II hazardous locations. The American Petroleum Institute publishes analogous standards in RP500 andRP505. Groups A, B, C, and D are for gases (Class I only). We will go deeper into ignition assessments in another blog. HAZARDOUS VS. These areas are in North America (United States and Canada) historically classified with the Class/Division system. The process of determining the type and size of hazardous locations is called classification. For equipment provided with threaded entries for NPT threaded conduit or fittings, listed conduit, conduit fittings, or cable fittings shall be used. It is created based on input from the Process Flow Diagrams, Piping & Instrumentation Diagrams and the Equipment Location Plan . Equipment is placed into protection level categories according to manufacture method and suitability for different situations. Flammable liquids with a high flash point are less hazardous than liquids Sources Division 1 and 2 Zone 0, 1 and 2 A (acetylene) IIC (acetylene & hydrogen) B (hydrogen) C (ethylene) IIB (ethylene) 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.
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