Upon detection, appropriate action is automatically taken, such as removing power, or providing notification. Group II is for explosive gases (Zone 0, 1 and 2) and Group III is for explosive dusts (Zone 20, 21 and 22). Hazardous area classification is a rigorous method of determining where an explosive environment may be present. The autoignition temperature is the lowest temperature at which the substance will ignite without an additional heat or ignition source (at atmospheric pressure). 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. 1: For examples of area classification drawings, see ANSI/API RP 505-2018, Informational Note No. area in which an explosive gas atmosphere is present continuously, or for long periods, or frequently (more than 10% of the time). The value is represented is volume percentage of oxygen. . November 2022 The inductance of the signal bell coils, combined with breaking of contacts by exposed metal surfaces, resulted in sparks, causing an explosion. ), Group F Carbon-based (eg. Both external and internal temperatures are taken into consideration. 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. Flameproof "d" - This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved. 1994-2020, W.W. Grainger, Inc. All Rights Reserved. Some other standards have more quantitative methods which require more knowledge of the plant, an example is the IEC standard 60079-10-1. Hazardous area classification. 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. 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. 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. This page was last edited on 20 January 2023, at 22:32. In the United States, the NEC uses 2 different classifications: Exception No. Area (mm2) CFD BS EN 60079-10-1:2009 1 5.0 5.0 0.0936 12.3 - 61.7 2 5.0 2.5 0.0326 6.17 - 30.8 A major safety concern in all workplaces is the occurrence of fires and explosions. October 2020 The minimum concentration of oxygen, necessary for the combustion to take place, is called the Limiting Oxygen Concentration. Documentation requirements likewise vary. This classification method provides a description of the hazardous material that may be present, and the probability that it is present, so that the appropriate equipment may be selected, and safe installation practices followed. 2: For the requirements for electrical and electronic. 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 So the following conditions must be met for an explosion to occur: Represented by the following explosion triangle. 1: As a guide to classification of Zone 22 locations, refer to ANSI/ISA 60079-10-2 (12.10.05)-2013, Explosive Atmospheres Part 10-2: Classification of areas Combustible dust atmospheres. Equipment that is safe for the location shall be of a type and design that the employer demonstrates will provide protection from the hazards arising from the combustibility and flammability of vapors, liquids, gases, dusts, or fibers involved. Zones 1 or 2. Iso Container Subscribe 6.9K views 2 years ago Oil and Gas Zone Classifications: A) Hazardous Area Classification It's cable reimagined No DVR space limits. When the concentration of methane is beneath the LEL, an explosion cannot occur, even when an ignition source is present. 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. Lets take a look at what defines each zone. December 2021 What is an Explosion Protection Document? Zone Hazardous Location 2 Table of . Ignitable concentrations of flammable gases or vapors which are present continuously or for long periods of time. So yes, it is important to choose the right model and always wonder what am I assessing?. area in which an explosive gas atmosphere is likely to occur occasionally in normal operation. But every hazardous area is different and each has specific requirements depending on the nature of the atmosphere and the elements that are present. Class 1/Div 2 ATEX Zone 2 Computers. October 2021 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. of the autoignition temperature of the hazardous atmosphere. 29 CFR 1910.307 Hazardous (classified) Locations January 2021 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 It is created based on input from the Process Flow Diagrams, Piping & Instrumentation Diagrams and the Equipment Location Plan . 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. Two possible classifications are described, in Section 18 (Zones), and Appendix J (Divisions). Coal mines, grain mills, elevators, and similar facilities likewise present the risk of a clouds of dust. Ways to ensure this level of safety are non-arcing design and limitation of the temperature of the equipment. Hazardous locations can also be described as those locations where electrical equipment 2: This classification includes, Informational Note No. HAZARDOUS VS. There are two systems in place, including the traditional North American Division system as well as the alternative Zone system. Zone 1: An area in which an explosive atmosphere is likely to occur in normal operation. Table 1. 10/1/20 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 These generally give rise to areas classied as Zones 0, 1, and 2 respectively. (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. July 2019 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. Enclosures can be pressurized with clean air or inert gas, displacing any hazardous substance. 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. 1: The term "Class I" was originally included as a prefix to, Informational Note No. 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 . The prevention of explosions in working environments is in most countries regulated in national laws and directives. IEC 60079-10-1 covers classification of explosive gas atmospheres, and IEC 60079-10-2 explosive dust. Each room, section, or area shall be considered individually in determining its classification. Refrigerated Equipment shall be marked to show the class, group, and operating temperature or temperature range, based on operation in a 40-degree C ambient, for which it is approved. CUTTING SKIPS 286 natural gas explosions per year in the U.S. causing substantial damage, severe injury or loss of lives. Atmospheres containing non-conductive dust. 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. Area classification documentations are reviewed and updated to reflect process changes. For methane this is shown in the following figure. [3], Different explosive atmospheres have chemical properties that affect the likelihood and severity of an explosion. Class I, Zone 0 or Zone 1 locations may not abut Class I, Division 1 or Division 2 locations. 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. Electrical equipment can and does cause fires and/or explosions in certain atmospheres. WHEN YOU NEED THEM. 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. 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. Please read Google Privacy & Terms for more information about how you can control adserving and the information collected. . 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. Container Accessories NEC has created an Americanized version of the IEC/CENELEC Zone system in a stand-alone article (Article 505). [4], Flammability of combustible liquids are defined by their flash-point. THE PRODUCTS YOU NEED, August 2018 Canada has a similar system with CSA Group standard C22.1, the Canadian Electrical Code, which defines area classification and installation principles. Article 505 National Electrical Code (NEC), Article 506 National Electrical Code (NEC). NEGATIVE PRESSURE ". Zone 2 Explosive Mixtures not likely to occur /occur short duration in normal operation (lt10 Hrs/ Yr). It uses the familiar Class/Division system and adapts the IEC/CENELEC Zones into it while maintaining NEC wiring methods and . The a subdivisions have the most stringent safety requirements, taking into account more than one independent component faults simultaneously. 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. Zone type (0/1/2/ 20/21/ 22) Zone extent. Category 3 equipment may only be used in zone 2 areas. Get more great content like this sent to your inbox. The specific hazardous materials within each group and their automatic ignition temperatures can be found in Article 500 of the National Electrical Code and in NFPA 497. 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. It is always balancing between not defining such areas too large (with highly costs for prevention of ignition sources) or too small (unsafe situations). June 2019 . NEC 2 Divisions (Div 1 2) Division I Comprising of Area Same as Zone 0 1. may exist under normal or abnormal conditions because of the presence of flammable gases or vapors, combustible dusts or ignitable fibers or flyings. This paper will discuss and review the current approaches and solutions of dealing with these HSE concerns, especially with the involvement of hazardous and potentially flammable and explosive chemicals. September 2019 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. Class I: hazardous because flammable gases or vapors are present in the air in quantities sufficient to produce explosive or ignitable mixtures: . to EN 1127-1): After the hazard area classification is completed, then the ignition assessment starts. 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. 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. It may exist because of repair, maintenance operations, or leakage. Areas with possible fire or explosion risks due to explosive atmospheres and/or mixtures - are called hazardous (or classified) locations or areas. [1] NEC article 500 describes the NEC Division classification system, while articles 505 and 506 describe the NEC Zone classification system. Accommodation Cabin Sources In recent years also the EPL is specified for several kinds of protection. October 2022 . 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. Since this fuel can only combust in the presence of oxygen, enough oxygen must be available for the rapid combustion to take place. Hazardous areas are those defined as areas of potential explosion risk due to the presence of flammable gas or vapor. 29 CFR 1910.399 Definitions Applicable to Subpart S Informational Note No. A hazardous area classification drawing (also known as an area classification drawing) outlines the classifications of areas where flammable liquids, gasses or vapors are handed, processed or stored. Sources of These applications will - due to browser restrictions - send data between your browser and our server. Then, the level of risk of an explosion is based on the frequency and duration of the occurrence of an explosive atmosphere. 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. Ignitable concentrations of flammable gases or vapors which are likely to occur under normal operating conditions. Informational Note No. Outside of the United States, the IEC uses two different classifications: Gas & Vapor (Zones 0, 1, or 2) Dust (Zones 20, 21, or 22) Step 2: The next step is to determine how often the hazardous substance (s) is/are present. Typical gas hazards are from hydrocarbon compounds, but hydrogen and ammonia are also common industrial gases that are flammable. 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. National Electrical Code (NEC) and the 1998 Canadian Electrical Code (CEC) now recognize the use of the Zone system for classification of hazardous areas. Ignition sources can be divided in 13 categories (acc. NFPA 70 NEC Zone Classification System The Zone Classification System is offered as an alternative to the Class and Division system. The design of the equipment must ensure protection, even in the event of rare incidents relating to the equipment. These areas only become hazardous in case of an accident or some unusual operating condition. Ex s is a coding referenced in IEC 60079-0. 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. Determining the Class, Division and Group or Zone and Group is critical to correctly applying the requirements for a given hazardous location. These generally give rise to areas classied as Zones 0, 1, and 2 respectively. Substance properties are specific for the amount of fuel needed to get an explosion when all other conditions are met. BATTERY ENERGY STORAGE SYSTEMBESS) But first, we must consider what is likely to cause an explosion in the first place. An explosion is a rapid expansion in volume associated with an extremely vigorous outward release of energy, usually with the generation of high temperatures and release of high-pressure gases (wikipedia (https://en.wikipedia.org/wiki/Explosion). The Class/Division/Group system is based on Article 500 of the National Electrical Code (NEC) where. |MWD/LWD Cabin Use this hazardous area guide to NFPA 70 location classes, divisions & groups to understand potentially dangerous situations at a glance. 3: For further information on the classification of, Informational Note No. When the concentration of gas or vapor is above the UEL the gas mixture is too rich to burn. Atmosphere containing a flammable gas, a flammable liquid produced vapor or a combustible liquid-produced vapor whose MESG is greater than 0.75 mm or MIC ratio is greater than 0.40 and less than 0.80 - such as carbon monoxide, ether, hydrogen sulfide, morphline, cyclopropane, ethyl, isoprene, acetaldhyde and ethylene or gases of equivalent hazard. Zone 2 hazardous areas are typically storage areas but can also be process areas. - 1 2 (Class 1, . Directly adjacent on the label one will find the mark of the listing agency. 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. Hazardous Area Classifications D103222X012 Product Bulletin 9.2:001 . Cookies are only used in the browser to improve user experience. Comparison of Zones and Divisions. The use of EPL and ATEX Category directly is an alternative for "s" marking. You can target the Engineering ToolBox by using AdWords Managed Placements. Since the changes to the code, hazardous locations with gases or vapors (Class I) present can be reclassified as Zone 0, 1 or 2. 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. Determined to be none of the above. If equipment is marked, for example, Ex e II T4 then it is suitable for all subgroups IIA, IIB and IIC. Hazardous Area Classifications D103222X012 Product Bulletin 9.2:001 September 2019. Dn 1 - a Ce e . 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 Raytec SPARTAN range includes dedicated luminaires for both Zone 1 and Zone 2 areas as well as industrial applications. 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. Group defines the type of the hazardous material in the surrounding atmosphere. 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: 0. [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. 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. Temporary Refuge Zone 1 is an area in which an explosive atmosphere is likely to occur occasionally in normal operation. Although every application is different, for the ease of monitoring and specification each hazardous area is classified as a particular level or zone. - 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 . 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. 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.