A spark or high heat must also be present. 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. Entire Vapour space of storage tank. Dn 1 - a Ce e . The IEC 60079 standard set has been adapted for use in Australia and New Zealand and is published as the AS/NZS 60079 standard set. ), Group F Carbon-based (eg. The codes and standards used in this process provide guidance for selecting,. Zone 1 - Explosive atmospheres are likely to occur. Carbon monoxide, ether, hydrogen sulfide, . Identifying Zone 0, Zone 1, and Zone 2 Hazardous Areas. November 2019 Readers with specific questions should refer to the applicable standards or consult with an attorney. >> NEC: Class I, Division 2, Group D. | IEC: Zone 2, Group II. Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications! less than 0.45 mm or MIC ratio is less than 0.40. It is always balancing between not defining such areas too large (with highly costs for prevention of ignition sources) or too small (unsafe situations). October 2018 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). Beside the Lower Explosion Limit, each substance also has an Upper Explosion Limit (UEL). Area classification documentations are reviewed and updated to reflect process changes. August 2018 MCC Shelter The Zone system has wider use in the chemical and petrochemical industries. Magnesium, Aluminum, Titanium etc. Division defines the probability of the hazardous material being present in an ignitable concentration in the surrounding atmosphere. 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. Temperature classification, except for intrinsically safe apparatus. An old British standard used letters to designate zones. Group II is for explosive gases (Zone 0, 1 and 2) and Group III is for explosive dusts (Zone 20, 21 and 22). 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. It is obvious to use those standards within these industries. Group defines the type of the hazardous material in the surrounding atmosphere. Often an area classification plan view is provided to identify equipment ratings and installation techniques to be used for each classified area. Although every application is different, for the ease of monitoring and specification each hazardous area is classified as a particular level or zone. Accommodation Cabin Division 1 and 2 Zone 0, 1 and 2 A (acetylene) IIC (acetylene & hydrogen) B (hydrogen) C (ethylene) IIB (ethylene) 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. 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. We don't save this data. 4: For further information on protection against static electricity and lightning hazards in hazardous (classified). This is also one of the first steps when composing an Explosion Protection Document. A high level of protection is ensured. The inductance of the signal bell coils, combined with breaking of contacts by exposed metal surfaces, resulted in sparks, causing an explosion. 11: For information on electric skin effect trace heating for hazardous (classified), Informational Note No. July 2021 A: No. 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. 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. | For Gas/Vapor this would be Zone 0. Flour, wood/sawdust, plastic dust), IIC Conductive dusts (eg. 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). This page was last edited on 20 January 2023, at 22:32. 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. 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. 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. 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. Dry Container 2: For the requirements for electrical and electronic. . 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. 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 approved for use in Class I hazardous locations cannot be used in Class II hazardous locations. Zones also have the added benefit of including the area classification with the zone description. 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. >> For Gas/Vapor this would be Zone 2. As a guide for Zone 0, this can be defined as over 1000 hours/year or >10% of the time. 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. November 2020 Encapsulation "m" -- This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved. What is an Explosion Protection Document? December 2021 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. These areas only become hazardous in case of an accident or some unusual operating condition. NFPA 70 NEC establishes area classifications based on Classes, Divisions and Groups that when combined delineate the hazardous conditions of a specific area. Category 2 equipment may be used in zone 1 or zone 2 areas. Hazardous areas are those defined as areas of potential explosion risk due to the presence of flammable gas or vapor. No long-term contract. Within the European Union, these are defined by IEC/EN standards (IEC/EN 60079-10-1 or 2) as directed by ATEX. 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). 10: For information on electrical resistance trace heating for hazardous (classified), Informational Note No. See Figure S-1 for an explanation of this marking. The last condition for an explosion is the presence of an effective ignition source in the direct contact with the fuel/air mixture. FREEZER 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. Ignitable concentrations of flammable gases or vapors which are not likely to occur under normal operating conditions and do so only for a short period of time. As mentioned, the first important step of achieving a safe work environment in relation to explosion safety is to identify and classify those areas, where a concentration of flammable gases or vapors within the flammable range can be present. Container Standards Standards and regulations exist to identify such locations, classify the hazards, and design equipment for safe use in such locations. So yes, it is important to choose the right model and always wonder what am I assessing?. Vertical. Directly adjacent on the label one will find the mark of the listing agency. So it is quite obvious that explosions should be prevented as much as possible and still work has to be done to achieve this. 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. This means that the electrical equipment is safe for use within these area by applying special protection strategies. Much early equipment having Ex s protection was designed with encapsulation and this has now been incorporated into IEC 60079-18 [Ex m]. . The escaping (hot) gases must sufficiently cool down along the escape path that by the time they reach the outside of the enclosure not to be a source of ignition of the outside, potentially ignitable surroundings. You will find this equipment in paint factories, a warehouse or around a bag dump station. Both external and internal temperatures are taken into consideration. Informational Note No. Explosion-proofing designs equipment to contain ignition hazards, prevent entry of hazardous substances, and, contain any fire or explosion that could occur. Article 505 National Electrical Code (NEC), Article 506 National Electrical Code (NEC). - 1 2 (Class 1, . NFPA 70 NEC Articles 505 and 506 cover the requirements for the Americanized Zone classification system as an alternative to the Class and Division classification system. Group is divided in three groups where Group I is reserved for mining locations. Various regulations use terms such as class, division, zone, and group to differentiate the various hazards. That is why the use of mobile phones on petrol forecourts are banned. March 2022 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. Zones compares to classes and divisions in the Class/Division system. International Electrotechnical Committee (IEC) Hazardous Area Classification. 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. . the inside of tank truck or the interior of a dust filter). Therefor Hazardous Area Classification (HAC) is the first important step in achieving an explosion safe installation or work environment. WELDING INSPECTION Determining the Class, Division and Group or Zone and Group is critical to correctly applying the requirements for a given hazardous location. 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. 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. A: When comparing Divisions and Zones, Division 2 is equivalent to Zone 2, but Division 1 is equivalent to either Zone 0 or 1. Explosion protection must be ensured during normal operation. Increased safety "e" -- This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved. 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. Subscribe 6.9K views 2 years ago Oil and Gas Zone Classifications: A) Hazardous Area Classification It's cable reimagined No DVR space limits. August 2020 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. For explosion hazards caused by flammable liquids or gases, the following zones are defined: So a zone 0 is the most hazardous zone and a zone 2 is a less hazardous zone. Classification of areas and selection of equipment and wiring methods shall be under the supervision of a qualified registered professional engineer. Some other standards have more quantitative methods which require more knowledge of the plant, an example is the IEC standard 60079-10-1. Atmospheres containing ethylene, propylene oxide, ethylene oxide, butadiene, cyclopropane, ethyl ether, or gases and vapors of equivalent hazard. Gas a. April 2022 Temporary Refuge The following content is only related to flammable substances and not to pyrotechnic substances or other instable substances, among those who can decompose. Temporary Refuge (TR) Shelter Hazardous Area Classification is a study, in which is assessed, at witch locations of a plant, factory or company, high concentrations of flammable gases are present or can be released, in order to create an explosion hazard. 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. Comparison of Zone 2 and Division 2 TABLE 1 - AREA CLASSIFICATIONS Division 1: Where ignitable concentrations can exist all of the time or some . 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. LIFTING TEST A Zone 0 location is a location in which one of the following . 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. Requirements for good HAC Drawings and Plans. 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. (between 0,1 and 10% of the time). 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. 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. The prevention of explosions in working environments is in most countries regulated in national laws and directives. 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. Explosions can cause significant damage along with severe injury or worse loss of life. of the autoignition temperature of the hazardous atmosphere. WHEN YOU NEED THEM. Controls can be fitted to detect dangerous concentrations of hazardous gas, or failure of countermeasures. 0. February 2022 What are 'Dark Factories,' and Do They Really Exist? This value of this LOC differs per substance and depends also on the inert gas for achieving a low oxygen concentration. Locations are thus classified by type and risk of release of gas, vapor, or dust. 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. 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. Therefore, it is very important to make sure that you are using a suitable luminaire for your application by choosing your fitting based on its suitability for the Zone in which it will be located. So for an explosion there must be enough fuel. All areas in the facility that are not Zone 0, Zone 1, or Zone 2 are considered unclassified. 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. 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. 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. Wide known is that al electrical equipment within hazardous areas must be Ex certified for use in the appropriate hazardous area (zone or class/division). 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. Area ClassificationThe max surface 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. Different countries have approached the standardization and testing of equipment for hazardous areas in different ways. The substance referred to by classhas a low probability of producing an explosive or ignitable mixture and is present only during abnormal conditions for a short period of time - such as a container failure or system breakdown. Class I: hazardous because flammable gases or vapors are present in the air in quantities sufficient to produce explosive or ignitable mixtures: . Refrigerated Typical gas hazards are from hydrocarbon compounds, but hydrogen and ammonia are also common industrial gases that are flammable. One of the hazards of working with flammable substances is an explosion, mostly hand in hand with fire. Group define the type of hazardous material and (partly) the location of the surrounding atmosphere. NEW METHODS FOR HAZARDOUS AREA CLASSIFICATION FOR EXPLOSIVE GAS . The plan may contain the list of chemicals with their group and temperature rating. To prevent explosions from happening in harsh environments whereby flammable gases or combustible dusts are present directives and guidelines are put in place to protect both the public, workforce, and environment. SPARTANs Zone 1 part code begins SPX, Zone 2 SPZ and industrial products having a SPI prefix. Type of protection "n" is further subdivided into nA, nC, and nR. Electronic equipment, including lighting, needs to be purpose designed for use in hazardous areas to prevent a spark occurring and igniting any flammable substances. In effect it is any method which can be shown to have the required degree of safety in use. Comparison of Zones and Divisions. Area which are not devided into Atex zones, are called non-hazardous area's. When equipment must be placed in a hazardous location, it can be designed to reduce the risk of fire or explosion. Equipment used in hazardous area must comply to certain Ex standards. Other ignition sources can also be present, like static electricity. February 2023 October 2021 In Europe the label must show the CE mark and the code number of the certifying/notified body). Equipment should be tested to ensure that it does not exceed 80%[according to whom?] 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 definition of the hazardous area zones represent the likelihood of hazardous gas, dust or other hazards being present in a working area. 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. February 2021 You can target the Engineering ToolBox by using AdWords Managed Placements. Area Classification - Hazardous Locations are classified by the likelihood of an ignitable concentration of combustible material being present. 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. Intrinsic safety designs equipment to operate using minimal energy, insufficient to cause ignition. Table 1. may exist under normal or abnormal conditions because of the presence of flammable gases or vapors, combustible dusts or ignitable fibers or flyings. Class I, Zone 0 or Zone 1 locations may not abut Class I, Division 1 or Division 2 locations. 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. 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). Informational Note No. 1910.307 (g) (2) It may exist because of repair, maintenance operations, or leakage. The label will always list the class, division and may list the group and temperature code. September 2020 This concentration is substance specific and lies normally somewhere between the LEL and UEL. But beside electrical equipment also mechanical equipment must be Ex certified, e.g. 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. . (1) Zone 0. A major safety concern in all workplaces is the occurrence of fires and explosions. [12], International Electrotechnical Commission, Occupational Safety and Health Administration, National Electrical Manufacturers Association, "Hazardous Area Classification and Control of Ignition Sources", "Hazardous (Classified) Locations NEC Articles 500 through 517", https://en.wikipedia.org/w/index.php?title=Electrical_equipment_in_hazardous_areas&oldid=1134828101, ignitable concentrations of combustible dust can exist, under normal conditions, ignitable concentrations of combustible dust are unlikely to exist normally, ignitable fibers, or materials producing combustible flyings, are handled, manufactured or used, easily ignitable fibers are stored or handled.
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