In Europe and the rest of the world - but also more and more in North America - the Zone system is used. Electrical equipment can and does cause fires and/or explosions in certain atmospheres. Some other standards have more quantitative methods which require more knowledge of the plant, an example is the IEC standard 60079-10-1. It is always balancing between not defining such areas too large (with highly costs for prevention of ignition sources) or too small (unsafe situations). 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. 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. For dusts: Zone 20, Zone 21 and Zone 22. 0. 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. 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. Zone 22 Zone 21 Zone20 A hazardous atmosphere formed by dust cloud in air is not likely to occur in . Which Standards to use for Hazardous Area Classification. Motors, lighting, junction boxes, electronic equipment, This method, being by definition special, has no specific rules. October 2019 But every hazardous area is different and each has specific requirements depending on the nature of the atmosphere and the elements that are present. Area Classification - Hazardous Locations are classified by the likelihood of an ignitable concentration of combustible material being present. Intrinsic safety designs equipment to operate using minimal energy, insufficient to cause ignition. 29 CFR 1910.399 Definitions Applicable to Subpart S 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. You will find these zones at the manifold of a tank truck or the interior of a silo. Class defines the general nature (or properties) of the hazardous material in the surrounding atmosphere. No representation is made that the information or references are complete or remain current. The housing may be strong enough to contain and cool any combustion gases produced internally. You can target the Engineering ToolBox by using AdWords Managed Placements. March 2021 MCC Shelter Enclosures can be pressurized with clean air or inert gas, displacing any hazardous substance. 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. The equipment housing may be sealed to prevent entry of flammable gas or dust into the interior. Equipment is non-incendive or non-sparking. 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 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. 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 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. There are several ways of how to perform hazardous area classification, all described in several standards or codes of practise. Definition of hazardous area zones (AS/NZS 60079.10): Zone 0 AddThis use cookies for handling links to social media. the National Fire Protection Association (NFPA) 70, National Electric Code(NEC). Zone 0 - Explosive atmospheres present continuously long periods or frequently. Group defines the type of the hazardous material in the surrounding atmosphere. No long-term contract. 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. The flash-point is the temperature at which the material will generate sufficient quantity of vapor to form an ignitable mixture. Some of our calculators and applications let you save application data to your local computer. 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 marked as suitable for IIB is also suitable for IIA but NOT for IIC. 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". 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. 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. The process of determining the type and size of hazardous locations is called classification. [3], Different explosive atmospheres have chemical properties that affect the likelihood and severity of an explosion. This has been replaced by a European numerical system, as set out in directive 1999/92/EU implemented in the UK as the Dangerous Substances and Explosives Atmospheres Regulations 2002. Adapters shall be used for connection to conduit or NPT-threaded fittings. 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. This is presented by the Lower Explosion Limit (LEL) of a substance. Then, the level of risk of an explosion is based on the frequency and duration of the occurrence of an explosive atmosphere. [4], Flammability of combustible liquids are defined by their flash-point. . For equipment provided with threaded entries for NPT threaded conduit or fittings, listed conduit, conduit fittings, or cable fittings shall be used. NFPA 70 NEC Zone Classification System The Zone Classification System is offered as an alternative to the Class and Division system. Temporary Refuge (TR) Shelter A spark or high heat must also be present. November 2020 As a guide for Zone 0, this can be defined as over 1,000 hours/year or >10% of the time. For example the EI 15 and API 500/505 describe specific installations and several conditions for the oil and gas industry. (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. It uses the familiar Class/Division system and adapts the IEC/CENELEC Zones into it while maintaining NEC wiring methods and . 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. January 2023 Zone 1 is an area that is classified 'as a place in which an explosive atmosphere consisting of a mixture with air or flammable substances in the form of gas, vapours and mists is likely to occur occasionally during normal operation', whereas Zone 2 is an area that is classified 'as a place in which an explosive atmosphere consisting of a mixture 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.) Sources of As a guide for Zone 0, this can be defined as over 1000 hours/year or >10% of the time. Container Accessories 2: Where gas detection, Informational Note No. June 2019 0,1 or 2: II B: I: 1 or 2: C: Acetone Benzene Butane Hexane . This article covers the requirements for the, Informational Note No. Coal mines, grain mills, elevators, and similar facilities likewise present the risk of a clouds of dust. 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. One of the hazards of working with flammable substances is an explosion, mostly hand in hand with fire. An old British standard used letters to designate zones. This is also one of the first steps when composing an Explosion Protection Document. In the United States, the NEC uses 2 different classifications: A room with a propane gas installation will typically be classified with the. Area ClassificationThe max surface temp. No hidden fees. Beside the Lower Explosion Limit, each substance also has an Upper Explosion Limit (UEL). 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. WHEN YOU NEED THEM. 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. 4: For further information on protection against static electricity and lightning hazards in hazardous (classified). The inductance of the signal bell coils, combined with breaking of contacts by exposed metal surfaces, resulted in sparks, causing an explosion. When the concentration of methane is beneath the LEL, an explosion cannot occur, even when an ignition source is present. 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. In some cases, it must be certified as meeting that standard. Zone 2 is a place in which an explosive atmosphere is not likely to occur in normal operation but, if it does occur, will persist for a short period only. Examples are: In another blog we, will explain how to perform Hazardous Area Classification according to the Standard EN-IEC 60079-10-1. *unless risk assessment states a higher or lower category is required. And safety must be guaranteed in the case of two faults occurring independently of each other. EN 16985 concerning spray cabins and powder coating cabins, EN 12779 related to extraction systems for hot sawdust and chips, EN 60079-10 series, 2020 version for gas and dust explosion hazard, NPR 7910 series for gas and dust explosion hazard based on EN 60079-10-1, 2015 version, EN 13617 for fuel dispensers at filling stations. 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. Zone 1 (unless separated by a fire wall)P.G.Sreejith, Kerala. NEC 2 Divisions (Div 1 2) Division I Comprising of Area Same as Zone 0 1. Home About Us News Hazardous Environment Classifications: NEC vs IEC, Posted March 11, 2019 by springercontrols. Recommendat ions. November 2022 of March 2022 These hazardous (classified) locations are assigned the following designations: For definitions of these locations, see 1910.399. Classification of areas and selection of equipment and wiring methods shall be under the supervision of a qualified registered professional engineer. Category 2 equipment may be used in zone 1 or zone 2 areas. Equipment is pressurised to a positive pressure relative to the surrounding atmosphere with air or an inert gas, thus the surrounding ignitable atmosphere can not come in contact with energized parts of the apparatus. April 2022 Zone 1 is an area in which an explosive atmosphere is likely to occur occasionally in normal operation. The value is represented is volume percentage of oxygen. 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 disadvantage of standards with example installations, is that a huge safety factor is incorporated and thus relative large hazardous area are defined. Areas with possible fire or explosion risks due to explosive atmospheres and/or mixtures - are called hazardous (or classified) locations or areas. Safe for the hazardous (classified) location. Google use cookies for serving our ads and handling visitor statistics. ethanol, methane or hydrogen. The required protection level is linked to the intended use in the zones described below: The equipment category indicates the level of protection offered by the equipment. Atmospheres containing propane, acetone, benzene, butane, methane, petrol, hexane, paint solvents or gases and vapors of equivalent hazard. 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. 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). 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. These would be then labeled with each of the individual methods. NEW METHODS FOR HAZARDOUS AREA CLASSIFICATION FOR EXPLOSIVE GAS . Informational Note No. NFPA 70 NEC Classes, Divisions and Groups. This temperature is used for classification for industry and technology applications.[6]. The Zone Classification System is offered as an alternative to the Class and Division system. Carbon monoxide, ether, hydrogen sulfide, . For gases, vapours and mists the zone classifications are recognised as Zone 0, Zone 1 and Zone 2 areas. Dn 1 - a Ce e . Hazardous Area Classifications D103222X012 Product Bulletin 9.2:001 September 2019. The minimum concentration of oxygen, necessary for the combustion to take place, is called the Limiting Oxygen Concentration. Hazardous Area Classification (HAC) is as follows: Definitions of hazardous area are different as per IEC and NEC. In many industrial, commercial, and scientific settings, the presence of such an atmosphere is a common, or at least commonly possible, occurrence. 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. The conduit shall be made wrench tight to prevent sparking when fault current flows through the conduit system and to ensure the explosionproof or flameproof integrity of the conduit system where applicable. POSITIVE PRESSURE 2: For Group IIIC combustible dusts or metal combustible fibers/flyings, there shall only be Zone 20 or 21 locations. Zone type (0/1/2/ 20/21/ 22) Zone extent. 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. Under the "Zone" system, hazards are defined for gas as Zone 0, 1 or 2, with 0 as the highest hazard, and for dust as Zone 20, 21 or 22, with 20 as the . PROCESS OF CONTAINER Explosion protection must be ensured during normal operation. 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. 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. >> For Gas/Vapor this would be Zone 0. Copryright 2023 Springer Controls Company . October 2022 . ADNOC This was accompanied by electrically-initiated explosions of flammable gas such as fire damp (methane) and suspended coal dust. - 1 2 (Class 1, . Temperature classification, except for intrinsically safe apparatus. Atmospheres containing combustible flyings. 286 natural gas explosions per year in the U.S. causing substantial damage, severe injury or loss of lives. For example, in the US by the Occupational Safety and Health Administration. Determined to be none of the above. 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. 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) 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. 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.
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