The plan may contain the list of chemicals with their group and temperature rating. That flammable gas or vapor . It is created based on input from the Process Flow Diagrams, Piping & Instrumentation Diagrams and the Equipment Location Plan . In many industrial, commercial, and scientific settings, the presence of such an atmosphere is a common, or at least commonly possible, occurrence. December 2013, All Only emails and answers are saved in our archive. You will find this equipment in paint factories, a warehouse or around a bag dump station. January 2023 . November 2020 hazardous areas as the following: An area where a potential hazard (e.g., a fire, an explosion, etc.) No representation is made that the information or references are complete or remain current. A differentiation is made between gas Ex zones and dust Ex zones: Gas Ex zones are 0/1/2 and dust Ex zones are 20/21/22. 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. 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. . Where pyrophoric materials are the only materials used or handled, these locations need not be classified. Then, the level of risk of an explosion is based on the frequency and duration of the occurrence of an explosive atmosphere. Zone 2 hazardous areas are typically storage areas but can also be process areas. Zones compares to classes and divisions in the Class/Division system. ADNOC For dusts: Zone 20, Zone 21 and Zone 22. TLS OFFSHORE CONTAINER In the United States, the hazardous location classification system is defined by the National Fire Protection Association (NFPA) 70, National Electric Code(NEC). Determining the Class, Division and Group or Zone and Group is critical to correctly applying the requirements for a given hazardous location. 14 4. 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. 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. Atmosphere containing carbonaceous dusts, Atmosphere containing combustible dust not included in Group E & F - such as. Refrigerated Oxygen is required in high quantities and in combination with the flammable substance to produce an explosive atmosphere. Ex Zone. This is an important factor in the classification of hazardous areas. 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". Equipment that is listed for a Zone 0 location may be installed in a Zone 1 or Zone 2 location of the same gas or vapor. 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. Atmospheres containing propane, acetone, benzene, butane, methane, petrol, hexane, paint solvents or gases and vapors of equivalent hazard. NEGATIVE PRESSURE In the IEC standards hazardous areas are classified into zones based upon the frequency and duration of an explosive atmosphere. Within a working area or installation an ignition can be created by many factors. All areas in the facility that are not Zone 0, Zone 1, or Zone 2 are considered unclassified. April 2021 area in which an explosive gas atmosphere is likely to occur occasionally in normal operation. Hazardous Area Classifications D103222X012 Product Bulletin 9.2:001 September 2019. The first thing to understand is that much like the metric vs imperial measuring systems, the United States uses its own methodology which differs from much of the world. July 2021 Ways to ensure this level of safety are non-arcing design and limitation of the temperature of the equipment. 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. 11: For information on electric skin effect trace heating for hazardous (classified), Informational Note No. Exception No. So for an explosion there must be enough fuel. Zone 1 - A place in which an explosive atmosphere is likely to occur in normal operation occasionally 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. Identifying Zone 0, Zone 1, and Zone 2 Hazardous Areas. RP 505 is referred to as the zone system. It is good to be aware of the fact that the mixture of flammable gas with oxygen has an optimum point where the combustion is most severe and leads to the highest explosion pressure. of Type of protection "n" -- This protection technique is permitted for equipment in the Class I, Zone 2 locations for which it is approved. Hazardous areas are classified into 3 zones based upon the frequency of the occurrence and duration of an explosive gas atmosphere, as follows: Zone 0 Area in which an explosive gas atmosphere is present continuously or for long periods or frequently. Home About Us News Hazardous Environment Classifications: NEC vs IEC, Posted March 11, 2019 by springercontrols. The NEC Zone system was created to harmonize with IEC classification system, and therefore reduce the complexity of management. Locations are thus classified by type and risk of release of gas, vapor, or dust. 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: The term "Class I" was originally included as a prefix to, Informational Note No. October 2019 Equipment should be tested to ensure that it does not exceed 80%[according to whom?] These applications will - due to browser restrictions - send data between your browser and our server. This article covers the requirements for the, Informational Note No. Intrinsic safety -- This protection technique is permitted for equipment in the Class I, Zone 0 or Zone 1 locations for which it is approved. When equipment must be placed in a hazardous location, it can be designed to reduce the risk of fire or explosion. The autoignition temperature is the lowest temperature at which the substance will ignite without an additional heat or ignition source (at atmospheric pressure). September 2019 In other cases, the atmosphere is normally non-hazardous, but a dangerous concentration can be reasonably foreseensuch as operator error or equipment failure. 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. Analysers, motors, control boxes, computers, Any arcs or sparks in this equipment has insufficient energy (heat) to ignite a vapour. For example, in the US by the Occupational Safety and Health Administration. . The following content is only related to flammable substances and not to pyrotechnic substances or other instable substances, among those who can decompose. To minimize the risk of these fires or explosions, electrical/electronic equipment must be designed, tested and labeled as being acceptable for use in the areas in which it is installed. There are three necessary components for an explosion to occur; This needs to be present in a relatively high quantity to produce an explosive mixture (e.g. A high level of protection is ensured. July 2020 Zone 1 (unless separated by a fire wall)P.G.Sreejith, Kerala. Ambient Temperature (-20C to +40C if not marked) Establish Zone Based on "IEC 60079-10". 1: Normal operation is considered the situation when plant, Informational Note No. Recommendat ions. THE CURRENT STANDARD . The International Electrotechnical Commission publishes the 60079 series of standards[2] which defines a system for classification of locations, as well as categorizing and testing of equipment designed for use in hazardous locations, known as "Ex equipment". Entire Vapour space of storage tank. Comparison of Zone 2 and Division 2 TABLE 1 - AREA CLASSIFICATIONS Division 1: Where ignitable concentrations can exist all of the time or some . Adapters shall be used for connection to conduit or NPT-threaded fittings. Controls can be fitted to detect dangerous concentrations of hazardous gas, or failure of countermeasures. Conversely if the same material is heated and handled above its flash-point, the area must be classified for proper electrical system design, as it will then form an ignitable mixture.[5]. ), Group F Carbon-based (eg. Readers with specific questions should refer to the applicable standards or consult with an attorney. It may exist because of repair, maintenance operations, or leakage. >> For Gas/Vapor this would be Zone 2. But when we take a closer look at the graph and table, we can conclude that any explosion, can easily lead to severe damage. 1910.307 - Hazardous (classified) locations. If equipment is marked, for example, Ex e II T4 then it is suitable for all subgroups IIA, IIB and IIC. Substance properties are specific for the amount of fuel needed to get an explosion when all other conditions are met. 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. When the concentration of gas or vapor is above the UEL the gas mixture is too rich to burn. So a zone 0 is the most hazardous zone and a zone 2 is a less hazardous zone. Ignitable concentrations of flammable gases or vapors which are likely to occur under normal operating conditions. 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. Q: Are Divisions and Zones equivalent to one another? November 2022 less than 0.45 mm or MIC ratio is less than 0.40. 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. NFPA 70 NEC Articles 500 through 503 cover the requirements for electrical/electronic equipment and wiring for all voltages in Class I, Divisions 1 and 2; Class II, Divisions 1 and 2; and Class III, Divisions 1 and 2 locations. March 2022 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). The definition of the hazardous area zones represent the likelihood of hazardous gas, dust or other hazards being present in a working area. Directly adjacent on the label one will find the mark of the listing agency. 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. Standards for electrical installations have been established and are governed by a variety of organizations throughout the world to ensure safe electrical systems in hazardous locations. 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. . Electrical equipment installed in such locations can provide an ignition source, due to electrical arcing, or high temperatures. 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. Copryright 2023 Springer Controls Company . In North America the suitability of equipment for the specific hazardous area must be tested by a Nationally Recognized Testing Laboratory, such as UL, FM Global, CSA Group, or Intertek (ETL). In some cases, the hazardous atmosphere is present all the time, or for long periods.