1910.307 - Hazardous (classified) locations. Refrigerated Container Group defines the type of the hazardous material in the surrounding atmosphere. Other ignition sources can also be present, like static electricity. To make this even easier to understand, take a look at the diagram of a typical petrol station below where we have identified the areas that are classified as Zone 0, Zone 1 and Zone 2. 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.) In 29 CFR 1910.307(c)(2)(ii), OSHA requires all equipment used in a hazardous location to be marked with the class, group and operating temperature or temperature range for which it is approved. 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. Hazardous Area Classification (HAC) is as follows: Definitions of hazardous area are different as per IEC and NEC. IEC 60079-10-1 covers classification of explosive gas atmospheres, and IEC 60079-10-2 explosive dust. Carbon monoxide, ether, hydrogen sulfide, . 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. August 2021 Increased safety "e" -- This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved. Type of protection "n" -- This protection technique is permitted for equipment in the Class I, Zone 2 locations for which it is approved. July 2020 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, a socket outlet labeled EEx'de' might have a case made to EEx 'e' and switches that are made to EEx 'd'. At least two British mine explosions were attributed to an electric bell signal system. Choose the right method for Hazardous Area Classification! The colour of the luminaire body indicates the level of protection. 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. 14 4. Ex s is a coding referenced in IEC 60079-0. In effect it is any method which can be shown to have the required degree of safety in use. 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. A spark or high heat must also be present. These areas only become hazardous in case of an accident or some unusual operating condition. Offshore Workshop Container The plan may contain the list of chemicals with their group and temperature rating. Locations are thus classified by type and risk of release of gas, vapor, or dust. As to the classification, they are the same. As a guide for Zone 0, this can be defined as over 1000 hours/year or >10% of the time. Area Classification - Hazardous Locations are classified by the likelihood of an ignitable concentration of combustible material being present. Electronic equipment, including lighting, needs to be purpose designed for use in hazardous areas to prevent a spark occurring and igniting any flammable substances. These ways of protection are specified in detail within several IEC standards (IEC 60079 series) for electrical equipment. | For Dust this would be Zone 21. THE CURRENT STANDARD . 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. FREEZER Well recognized and clear IEC Standard IEC 60079-10-2:2015 Hazardous Area Classification for explosive dusts Significant influence on spending's for safety . Explosion-proofing designs equipment to contain ignition hazards, prevent entry of hazardous substances, and, contain any fire or explosion that could occur. 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". The Zone Classification System is offered as an alternative to the Class and Division system. For liquids, gases and vapours: Zone 0, Zone 1 and Zone 2. Division defines the probability of the hazardous material being present in an ignitable concentration in the surrounding atmosphere. 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. Groups A, B, C, and D are for gases (Class I only). [3], Different explosive atmospheres have chemical properties that affect the likelihood and severity of an explosion. the inside of tank truck or the interior of a dust filter). 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. You will find these zones at the manifold of a tank truck or the interior of a silo. This temperature is used for classification for industry and technology applications.[6]. A special standard for instrumentation is IEC/EN 60079-27, describing requirements for Fieldbus Intrinsically Safe Concept (FISCO) (zone 0, 1 or 2) (This special standard has been withdrawn, and has been partially replaced by: IEC/EN60079-11:2011 and IEC/EN60079-25:2010)[1], A special standard for instrumentation is IEC/EN 60079-27, describing requirements for Fieldbus Non-Incendive Concept (FNICO) (zone 2) (This special standard has been withdrawn, and has been partially replaced by: IEC/EN60079-11:2011 and IEC/EN60079-25:2010)[9]. of the autoignition temperature of the hazardous atmosphere. Equipment is placed into protection level categories according to manufacture method and suitability for different situations. 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. Hazardous area classification is a rigorous method of determining where an explosive environment may be present. 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). Comparison of Zone 2 and Division 2 TABLE 1 - AREA CLASSIFICATIONS Division 1: Where ignitable concentrations can exist all of the time or some . 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. 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. 2: For Group IIIC combustible dusts or metal combustible fibers/flyings, there shall only be Zone 20 or 21 locations. The upper explosion limit of a substance is the highest concentration (in volume percentages for gases and liquids) of a gas or a vapor in air capable of producing a flash of fire in the presence of an ignition source. The overpressure is monitored, maintained and controlled. gas, vapours, mists and dusts). July 2019 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 In Europe the label must show the CE mark and the code number of the certifying/notified body). 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. 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 Informational Note No. 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. July 2022 Each chemical gas or vapour used in industry is classified into a gas group. So the following conditions must be met for an explosion to occur: Represented by the following explosion triangle. 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. Canada has a similar system with CSA Group standard C22.1, the Canadian Electrical Code, which defines area classification and installation principles. Division II Comprising of Area Same as Zone 2. 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). Group is divided in three groups where Group I is reserved for mining locations. The following content is only related to flammable substances and not to pyrotechnic substances or other instable substances, among those who can decompose. 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. In many industrial, commercial, and scientific settings, the presence of such an atmosphere is a common, or at least commonly possible, occurrence. Arcing electrical equipment in unclassified . Examples are: In another blog we, will explain how to perform Hazardous Area Classification according to the Standard EN-IEC 60079-10-1. Equipment marked as suitable for IIB is also suitable for IIA but NOT for IIC. A major safety concern in all workplaces is the occurrence of fires and explosions. 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. 2: For the requirements for electrical and electronic. An area where combustible dusts or ignitable fibers and flyings are likely to occur under normal operating conditions. It is essential to know which zone you are working in, so that you can specify the most appropriate equipment.