Australia and New Zealand use the same IEC-60079 standards (adopted as AS/NZS60079), however the CE mark is not required. Area ClassificationThe max surface temp. Beside sufficient fuel, also sufficient oxygen is needed for combustion of the mixture. Ways to ensure this level of safety are non-arcing design and limitation of the temperature of the equipment. For liquids, gases and vapours: Zone 0, Zone 1 and Zone 2. Some of our calculators and applications let you save application data to your local computer. Substance properties are specific for the amount of fuel needed to get an explosion when all other conditions are met. 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. Safety is ensured in the event of frequently occurring disturbances or equipment faults which normally have to be taken into account. All rights reserved. We don't save this data. 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. Zone 1 (unless separated by a fire wall)P.G.Sreejith, Kerala. For example, in the US by the Occupational Safety and Health Administration. The prevention of explosions in working environments is in most countries regulated in national laws and directives. Equipment that the employer demonstrates will provide protection from the hazards arising from the flammability of the gas or vapor and the zone of location involved and will be recognized as providing such protection by employees need not be marked. It may exist because of repair, maintenance operations, or leakage. December 2013, All MCC Shelter 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). (between 0,1 and 10% of the time). Container Accessories 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. September 2022 area in which an explosive gas atmosphere is present continuously, or for long periods, or frequently (more than 10% of the time). Hazardous areas are those defined as areas of potential explosion risk due to the presence of flammable gas or vapor. 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. Coal mines, grain mills, elevators, and similar facilities likewise present the risk of a clouds of dust. So a zone 0 is the most hazardous zone and a zone 2 is a less hazardous zone. Sources of Readers with specific questions should refer to the applicable standards or consult with an attorney. 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. WATER TIGHTNESS coal and charcoal), Group G Nonconductive dusts (eg. Offshore Living Quarter 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. Zone 0 is an area in which an explosive atmosphere is present continuously for long periods of time or will frequently occur. Quick Tips #124.1. ), Group F Carbon-based (eg. Group is divided in three groups where Group I is reserved for mining locations. These are typically process areas where gases are more likely to be present. Division defines the probability of the hazardous material being present in an ignitable concentration in the surrounding atmosphere. NEGATIVE PRESSURE Equipment is non-incendive or non-sparking. The more hazardous the area to more safety measures have to be taken in order to prevent equipment becoming an effective source of ignition. ADNOC Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications! Directly adjacent on the label one will find the mark of the listing agency. 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). 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. Laboratory Container Other ignition sources can also be present, like static electricity. Different countries have approached the standardization and testing of equipment for hazardous areas in different ways. Gases, Vapors and Mists. SEWAGE TREATMENT That is why the use of mobile phones on petrol forecourts are banned. So the following conditions must be met for an explosion to occur: Represented by the following explosion triangle. 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). But when we take a closer look at the graph and table, we can conclude that any explosion, can easily lead to severe damage. Dry Container This equipment is intended for use in Zone 1 (gases) or Zone 21 (dusts). 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. Not only are hazardous areas classified by Class (nature of the hazardous material,) and Division . Only emails and answers are saved in our archive. The Occupational Safety and Health Administration (OSHA) has adopted these hazardous classifications and all except Groups are defined in 29 Code of Federal Register (CFR) 1910.399. Employers may use the zone classification system as an alternative to the division classification system for electric and electronic equipment and wiring for all voltage in Class I, Zone 0, Zone 1, and Zone 2 hazardous (classified) locations where fire or explosion hazards may exist due to flammable gases, vapors, or liquids. Zone 2 Explosive Mixtures not likely to occur /occur short duration in normal operation (lt10 Hrs/ Yr). area in which an explosive gas atmosphere is likely to occur occasionally in normal operation. Temperature Control This was accompanied by electrically-initiated explosions of flammable gas such as fire damp (methane) and suspended coal dust. 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. 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. 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. - Zone 0: An area where an explosive gas-air mixture is continuously present or present for long time (continuous hazard, whose estimated duration is higher than 1000 hours/year) - Zone 1: An area where an explosive gas-air mixture is likely to occur during normal . 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. Identifying Zone 0, Zone 1, and Zone 2 Hazardous Areas. Shown below is a summary of the applicable NEC Articles to reference to ensure the proper requirements are applied. These hazardous (classified) locations are assigned the following designations: For definitions of these locations, see 1910.399. June 2020 Adapters shall be used for connection to conduit or NPT-threaded fittings. Whenever you are filling up your tank you are standing in a Zone 1 hazardous area. Temporary Refuge It is essential to know which zone you are working in, so that you can specify the most appropriate equipment. Equipment can be designed or modified for safe operation in hazardous locations. Carbon monoxide, ether, hydrogen sulfide, . There are two sets of Zones: Zones 0 thru 2 are used for gases, vapors, and mists, and Zones 20 thru 22 are . When the concentration of methane is beneath the LEL, an explosion cannot occur, even when an ignition source is present. 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 . 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. Beside the Lower Explosion Limit, each substance also has an Upper Explosion Limit (UEL). NEC has created an Americanized version of the IEC/CENELEC Zone system in a stand-alone article (Article 505). Lets take a look at what defines each zone. 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. 10/1/20 Locations are thus classified by type and risk of release of gas, vapor, or dust. Photo 2. The NEC Zone system was created to harmonize with IEC classification system, and therefore reduce the complexity of management. THE CURRENT STANDARD . 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. 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." See below for further details: Division system sample marking Then, the level of risk of an explosion is based on the frequency and duration of the occurrence of an explosive atmosphere. For more detailed assessments or for situations where no specific industry standards are available , like the chemical or pharmaceutical sector and also specific installation for oil and gas industries, a more quantitative approach can be used. Equipment construction is such that it can withstand an internal explosion and provide relief of the external pressure via flamegap(s) such as the labyrinth created by threaded fittings or machined flanges. 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". Type of protection "n" -- This protection technique is permitted for equipment in the Class I, Zone 2 locations for which it is approved. October 2022 Hazardous classified locations are areas where the possibility of fire or explosion hazards may exist under normal or abnormal conditions because of the presence of flammable, combustible or ignitable gases, vapors, liquids, dust, or fibers/flyings. may exist under normal or abnormal conditions because of the presence of flammable gases or vapors, combustible dusts or ignitable fibers or flyings. As to the classification, they are the same. Sources The process of determining the type and size of hazardous locations is called classification. The inductance of the signal bell coils, combined with breaking of contacts by exposed metal surfaces, resulted in sparks, causing an explosion. 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. International Electrotechnical Committee (IEC) Hazardous Area Classification. Arcing electrical equipment in unclassified . Zone 0/20: An area in which an explosive atmosphere is present continuously or for long periods or frequently. 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. according to ISO standard 80079 series. The autoignition temperature is the lowest temperature at which the substance will ignite without an additional heat or ignition source (at atmospheric pressure). Refrigerated Container July 2020 Zone 1 fittings are supplied as silver, Zone 2 as dark grey and industrial fittings as white. the inside of tank truck or the interior of a dust filter). July 2021 >> NEC: Class II, Division 1, Group F. | IEC: Zone 20, Group IIC. For dusts: Zone 20, Zone 21 and Zone 22. If equipment is marked, for example, Ex e II T4 then it is suitable for all subgroups IIA, IIB and IIC. This article covers the requirements for the, Informational Note No. Comparison of Zones and Divisions. For example the EI 15 and API 500/505 describe specific installations and several conditions for the oil and gas industry. When equipment must be placed in a hazardous location, it can be designed to reduce the risk of fire or explosion. In order to understand hazardous area classification it is important to understand which factors contribute to the occurrence of an explosion. Ex LIGHTER-THAN-AIR GASES & VAPOURS Vapour density of 0.75 is considered as the boundary between lighter and heavier gases / vapours as a safety measure HA of a leak source located in air Source of hazard 4.5 m. 8.0 m R 4.5 m H Independent test housesNotified Bodiesare established in most European countries, and a certificate from any of these will be accepted across the EU. Flour, wood/sawdust, plastic dust). 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. 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. HAZARDOUS VS. 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. Drop Test The hazardous area classification system determines required protection techniques and methods for electrical installations in the location. Class 1/Div 2 ATEX Zone 2 Computers. Requirements for good HAC Drawings and Plans. 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. Temporary Refuge (TR) Shelter Magnesium, Titanium), IIB Nonconductive dusts (eg. Equipment approved for Class I, Division 1 or Class 1, Division 2 shall, in addition to being marked in accordance with (c)(2)(ii), be marked with the following: Class I, Zone 1 or Class I, Zone 2 (as applicable); Applicable gas classification groups; and. This page was last edited on 20 January 2023, at 22:32. BATTERY ENERGY STORAGE SYSTEMBESS) 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. The NEMA enclosure rating or IP code may also be indicated, but it is usually independent of the Classified Area suitability. 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. These ways of protection are specified in detail within several IEC standards (IEC 60079 series) for electrical equipment. Such properties include flame temperature, minimum ignition energy, upper and lower explosive limits, and molecular weight. A major safety concern in all workplaces is the occurrence of fires and explosions. November 2021 Ignition sources can be divided in 13 categories (acc. NFPA 70, the National Electrical Code (NEC), defines area classification and installation principles. 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. SIGN UP FOR EMAILGet more great content in your inbox. WHEN YOU NEED THEM. 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. 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 Zone type (0/1/2/ 20/21/ 22) Zone extent. * Zone 2 a . The following Equipment Groups and Categories are applicable: Equipment in this category is only intended for use in the underground areas of mines, as well as those areas of surface installations of such mines endangered by firedamp and/or combustible dusts. 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. Q: Can I use a piece of equipment approved for use in a Division 1 hazardous location in a Division 2 hazardous location? This is also one of the first steps when composing an Explosion Protection Document. Area which are not devided into Atex zones, are called non-hazardous area's. 1.1.2 This recommended practice provides information on specific flammable gases and vapors, flammable liquids . Type of protection "n" is further subdivided into nA, nC, and nR. Upon detection, appropriate action is automatically taken, such as removing power, or providing notification. 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. 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. Since the changes to the code, hazardous locations with gases or vapors (Class I) present can be reclassified as Zone 0, 1 or 2. There are two systems in place, including the traditional North American Division system as well as the alternative Zone system. The above groups are formed in order of how explosive the material would be if it was ignited, with IIC being the most explosive zone system gas group and IIA being the least. These generally give rise to areas classied as Zones 0, 1, and 2 respectively. Entire Vapour space of storage tank. 1.1 Scope. Division II Comprising of Area Same as Zone 2. 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). A potential few examples of this are: The air space inside a tank of petrol 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. 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. National Electric Code 2020 edition National Fire Protection Association. One of the hazards of working with flammable substances is an explosion, mostly hand in hand with fire. Marking "EEx d" in Accordance with EN 50 0 14 and 50 018 . Classification of Hazardous Areas 0 100 200 300 400 500 600 T1 >450C T2 >300C 450C T3 >200C 300C T4 >135C 200C . October 2018 Informational Note No. Use this hazardous area guide to NFPA 70 location classes, divisions & groups to understand potentially dangerous situations at a glance. This means that the electrical equipment is safe for use within these area by applying special protection strategies. May 2021 If you want to promote your products or services in the Engineering ToolBox - please use Google Adwords. This concentration is substance specific and lies normally somewhere between the LEL and UEL. Equipment meeting one or more of the protection techniques described in paragraph (g)(3) of this section shall be marked with the following in the order shown: Class, except for intrinsically safe apparatus; Zone, except for intrinsically safe apparatus; Occupational Safety and Health Administration, Outreach Training Program (10- and 30-hour Cards), OSHA Training Institute Education Centers, Severe Storm and Flood Recovery Assistance. Zone 1 is an area in which an explosive atmosphere is likely to occur occasionally in normal operation. 10: For information on electrical resistance trace heating for hazardous (classified), Informational Note No. This can be achieved by blanketing with nitrogen or carbondioxide. Read more in our blogWhich Standards to use for Hazardous Area Classification. Equipment in this category is intended for use in areas in which explosive atmospheres caused by gases, vapours, mists or air/dust mixtures are likely to occur occasionally. 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. The last condition for an explosion is the presence of an effective ignition source in the direct contact with the fuel/air mixture. . Informational Note No. 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.
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