Design, testing, certification, installation & maintenance

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1 Legislation, Standards and Technology Design, testing, certification, installation & maintenance of electrical equipment in hazardous locations in India by Wolfgang Berner, Ashwini Bondale and Manikandan Parthasarathy While there has been done a lot of harmonization in area of hazardous location classification and regarding the equipment design, testing and installation around the world over the last decades, there are still significant differences in the product design, testing and installation requirements between the International Electrical Commission (IEC) and Indian system. This makes it difficult for international manufacturers and end-users. The paper will provide and overview on the codes and standards currently used for the testing, certification, installation and maintenance of explosion protected electrical equipment in hazardous locations in India. It will also discuss the basic requirements and procedures for importers for getting CCoE (Chief Controller of Explosives) product approvals by PESO (Petroleum and Explosion Safety Organization) or DMGS (Director General of Mines Safety), and the challenges of this system. The following topics will be addressed in the paper: > Product codes and standards > Product testing and certification > Product conformity assessment procedures > Product approval - Statutory acts and rules > Product selection, installation and maintenance > Differences and alignment with International codes, standards, processes and procedures (ISO, IEC, NEC and CEC) Standardization in the field of Explosion Protecion Bureau of Indian Standards (BIS) The roots of the Bureau of Indian Standards (BIS) date back to India s pre-independence era. During this period standardization activity was largely sporadic and was confined to a few government organizations. Today, BIS is the national code laying body in India, established under the Bureau of Indian Standards Act Its main objective is the harmonious development of the standardisation activities, quality certification of goods and services, and marking. Standards Development Process The standards formulation activity within BIS is carried out through 14 Division Councils, each responsible for its respective field of engineering, science and technology. The Electrotechnical Division Council (ETDC) is responsible for the standardization in the field of electrical power generation, transmission, distribution and utilization equipment, insulating materials, winding wires, measuring and process control instruments and primary and secondary batteries. The work of the Electro Technical Division Council carried out through 37 Sectional Committees. The primary duty of the Sectional Committees are the development and systematic review of Indian Standards within their field. One of the EDTC Sectional Committees is ET 22 - Electrical Apparatus for Page 12 Ex-Magazine 2011

2 Explosive Atmospheres. Its scope is to prepare guidelines and requirements for electrical equipment for use in explosive atmospheres with the possible presence of ignitable gas, vapor, liquid, or dust. This includes area classification, equipment design and construction, testing, selection, installation, inspection, maintenance, repair and overhaul of explosion protected equipment. ET 22 has in principle decided to further harmonize the national standards with corresponding international standards. Therefore, the standardization activity at national level closely follows that of the International Electrotechnical Commission. ET 22 participates in the standardization activity at international level. India is a participating member of the IEC Technical Committee TC 31 Equipment for Explosive Atmospheres. International Codes and Standards and their Relevance in the Indian Scenario IEC is the international body for developing codes and standards for electrical apparatus used in hazardous areas. CENELEC has this role in Europe. The situation is slightly different in the USA, where the National Electrical Code (NEC) covers the installation requirements, and product codes and standards are formulated by organizations like Underwriters Laboartories (UL),the International Society of Automation (ISA), and the American National Standards Institute (ANSI). Many countries in the world, including India, in certain cases accept these international codes and standards for imported explosion protected products. At present, the various Indian codes and standards for explosion protected equipment are very old. Many of the codes and standards are based on European EN, Internation- al IEC, British or German VDE standards which have undergone multiple changes and updates in the meantime. Europe for example has adopted the ATEX Directives 94/9/EC for manufacturers and 99/92/EC for end-users, and the CENELEC standards are completely harmonized with the IEC standards. This has led to the situation that BIS standards are not up to date with the international codes and standards anymore. Due to this explosion protected products designed, tested and approved to Indian BIS standards are not meeting the requirements to the current international markets, and vice versa. This is a challenge for Indian manufacturers wanting to export their equipment to countries based on an up-to-date IEC system, and for importers to India. Products have to be designed, tested and approved to both systems. At present various BIS codes and standards for explosion protected equipment are being harmonised with IEC standards. However some standards, like the one for the selection and installation of explosion protected electrical equipment, are adopted with a lot of modifications and variations as Indian standards. This puts Indian manufacturers and users at a disadvantage with international manufacturers and users. One example is that IEC allows the use of equipment of type of protection Increased Safety e in Zone 1 locations whereas the BIS standard does not permit this, and restricts its use to Zone 2 areas only. This leads to additional cost for users due to the required use of equipment of type of protection Flameproof Enclosures d in places where Ex e / Ex d equipment could be used. In addition, with the current standards development procedures and processes within BIS, the adoption of the IEC standards takes a very long time. A list of the currently published standards developed by ET 22 is shown in Table 4. Product testing and certification The testing and certification of explosion protected products in India are being conducted to the relevant Indian standards under the product licensing scheme of the Bureau of Indian Standards. The tests are carried out in one of the test laboratories recognized by the Director General of Mines Safety (DGMS), Chief Controller of Explosive (CCoE) and BIS: In India, the Central Institute of Mining & Fuel Research (CIMFR) in Dhanbad, the Central Power Research Institute (CPRI) in Bangalore, the Electronics Regional Testing Lab (ERTL) in Kolkata, Karandikar Laboratories Pvt. Ltd. (KLPL) and Intertek Lab offer product testing and certification facilities for explosion protected equipment. Karandikar Laboratories also has a technical cooperation with BASEEFA in England. In case of products imported from other countries, two different mechanisms are relevant in India. To obtain DGMS approval of such products, testing at one of the DGMS recognised laboratories in India is essential as well as the field trail testing. Compliance reports from the country of origin of such products are currently not acceptable. For PESO approval, on the other hand, test reports from the foreign test laboratory are considered (for further information see paragraph titled Product Approval). Ex-Magazine 2011 Page 13

3 Design, testing, certification, installation & maintenance in India Product Conformity Assessment The Bureau of Indian Standards BIS is empowered to license manufacturers for the use of the Indian Standards Quality Mark for explosion protected equipment, and is governed by the provisions of the Bureau of Indian Standards Act Such a manufacturing license is only needed for equipment with types of protection Flameproof Enclosures d and Intrinsic Safety i. Other types of protection are not covered under the BIS quality license and mark scheme. The BIS license is needed to receive a product approval from the relevant statutory bodies, which is described in the following paragraph. Product approval statutory acts and rules Petroleum and Explosive Safety Organization The main objective of the Petroleum Explosive Safety Organization (PESO) formerly Department of Explosives is to ensure safety and security of public and property from fire and explosion. The organization as a statutory authority which is entrusted with the administration of the Explosives Act, 1884 and the Petroleum Act, 1934, and the rules framed under these Acts; to regulate and monitor the manufacture, import, export, transport, possession, sale and use of explosives, petroleum products and compressed gases as envisaged under these Acts. These Acts and their structures are described briefly in the following. Explosive Act Explosives Rules, Gas Cylinder Rules, Static & Mobile Pressure Vessels (Unfired) Rules, Notification No. GSR 625(E) dated regarding Acetylene Generation Petroleum Act Petroleum Rules, Calcium Carbide Rules, Cinematography Film Rules, 1948 The basic activities of the Petroleum explosive Safety Organisation for the above mentioned Acts and Rules are described briefly in the following. Explosive Rules 2008 The major work of PESO under the Explosives Rules, 2008 relates to granting approval, licences for manufacture of explosives, authorization of explosives, storage of explosives, import/export of explosives, transport of explosives by road and packaging for explosives etc. prescribing safe procedures and methods for manufacture of various types of explosives including the tools, equipments and machineries. The organization also carries out investigation of accidents involving explosives and destruction of unserviceable and seized explosives in the interest of public safety and security. In addition PESO also carries out inspection and audit of the new premises for verification/endorsement at the time of grant of licences/approvals and also periodic inspections of the licensed/approved premises. Petruleum Rules 2002 Petroleum has been defined under the Act and Rules as liquid hydrocarbon or a mixture of liquid hydrocarbons and any inflammable mixture containing liquid hydrocarbons. The work relating to administration of these Rules covers the approval of refineries, petrochemical, oil and gas processing facilities, transport of petroleum by water, land and pipeline, flameproof and other safety equipments for use in areas with flammable gases, and the licensing of storage installations, tank trucks for transportation by road and air. The organization carries out inspections of these premises to ensure the compliance with the rules and safety measures. The Petroleum Explosive Safety Organisa- Page 14 Ex-Magazine 2011

4 tion is currently involved in the regulation of over premises all over India.The approval of the Chief Controller of Explosives (CCoE) is mandatory for all electrical equipment installed in potentially explosive atmospheres. Rule 106 of the Petroleum Rules 2002 defines that all electrical equipment used in hazardous locations requires a CCoE approval. The approval of such equipment is therefore limited to only such areas falling within the jurisdiction of the Petroleum and Explosives Safety Organization. The Chief Controller of Explosives permits the use of equipment with types of protection Flameproof Enclosures d, Intrinsic Safety i, and Encapsulation m for use in Zone 1 hazardous areas. Non-sparking n and Increased Safety e equipment are permitted in Zone 2 areas only. Process for CCoE Approval for Explosion Protected Equipment Both, electrical equipment for use in hazardous location manufactured in India or manufactured outside of the country and imported into India, need a PESO approval before they can be installed and be put in use. Table1 describes the procedure how to obtain the PESO approval for electrical equipment manufactured in India. Table 2 shows the procedure to obtain a PESO approval for imported electrical equipment: Requirements 1 Infrastructural facilities 2 Engineering infrastructure 3 Equipment description Description Details of infrastructural facilities for production available with manufacturer. This includes details of manufacturing works, equipment available, testing facilities available, technical manpower availability and quality control setup. Details of infrastructure available for providing engineering back up for the products marketed. Technical details of the equipment including engineering drawings. 4 Certification Certificate from approved test labs confirming that the prototype of the equipment has passed the tests prescribed by the relevant standards. 5 BIS license Copy of the BIS license confirming that the manufacturing of the equipment is covered under a quality control scheme. This requirement is mandatory for equipment of type of protection Flameproof Enclosures d. For other types of explosion protected equipment, the CCoE grants approval just based on a test certificate. Note 1: The above mentioned documents have to be submitted before or during starting the manufacturing of the equipment. Table 1: PESO approval for equipment manufactured in India Requirements 1 Manufacturer's Company Profile 2 Previous clients/projects name list 3 Company profile of the Indian agent Description Details of the profile of the manufacturer to be submitted. Profile of the user of such type of equipment in other countries to be submitted. Profile of the Indian agent for the manufacturer in the country. 4 Infrastructural facilities Infrastructural facilities available with the Indian agent for providing technical support for the equipment in the country. 5 Agreement between manufacturer and Indian agent 6 Technical description of equipment 7 Certification from IEC or EN notified bodies A copy of the agreement between manufacturer and the Indian agent spelling out the responsibilities for providing technical back up for the equipment and training support to personnel of the Indian agent for such support to be submitted. Technical description of the equipment including drawings wherever applicable. Certification for the equipment from an IEC or ATEX notified body. The certificate should also include both prototypes as well as conformity assessment certification (certificates like ATEX, IECEx etc.). Note 1: Foreign vendors and original equipment manufacturers are required to receive the PESO approval certificate before supplying the equipment to India. Note 2: the above mentioned documents have to be submitted before or during starting the manufacturing of the equipment. Table 2: PESO approval for equipment imported into India Ex-Magazine 2011 Page 15

5 Design, testing, certification, installation & maintenance in India Area classification, selection, installation and maintennace of equipment Area classification As described above, the Petroleum Explosive Safety Organisation has been entrusted with the administration of two important Acts of the Government of India. One is the Explosives Act and the other one is the Petroleum Act Three important safety regulations, the Petroleum Rules 2002, Static & Mobile Pressure Vessels Rules 1981 and Gas Cylinder Rules 1981 fall within the jurisdiction of the above Acts. These regulations cover safety in activities ranging from refining, handling, transportation to storage of petroleum as well as other flammable compressed gases. The Petroleum Rules 2002, provide specific directions in regards to hazardous areas, their classification, the extent of hazardous areas and the selection of equipment for use in various types of hazardous areas. These rules are used in conjunction with the Indian Standard IS Classification of hazardous areas (other than mines) having flammable gases & vapors for electrical installation, using the IEC-based zone classification system. Selection of Equipment The following information is required for proper selection of explosion protected equipment in hazardous areas: > Classification of hazardous area > Temperature class and ambient temperature > Gas group classification > Environmental condition Selection of Equipment per Zone Indian statutory and regulatory organizations like PESO and BIS as well as consultants like Engineers India Limited (EIL) follow the Indian Standard IS Guide for Selection and Installation of Electrical Equipment in Hazardous Areas (other than Mines) for selecting and installing equipment in hazardous locations. Table 3 lists the equipment type of protection and its suitability for the appropriate hazardous location. Installation of Equipment Electrical installations in hazardous areas shall comply with the following requirements in addition to the appropriate requirements in non-hazardous areas. The electrical apparatus must be used within power, current, frequency, duty ratings and such other characteristics. It must be also ensured that temperature classification for the apparatus has been established for above ratings. The selection and installation of the electrical apparatus follows IS Guide for selection of electrical equipment for hazardous area in conjunction with IS Code of practice for the selection, installation and maintenance of electrical apparatus for use in potentially explosive atmospheres (other than mining application or explosive processing manufacture). Type of Protection Relevant IS Standard Suitable for Zone Intrinsic Safety Ex ia IS/IEC Zone 0, 1 and 2 Intrinsic Safety Ex ib IS/IEC Zone 1 and 2 Flameproof Enclosures Ex d IS/IEC Zone 1 and 2 Pressurized or Purged Ex p IS/IEC Zone 1 and 2 Encapsulation Ex m IS/IEC Zone 1 and 2 Powder Filled Ex q IS/IEC Zone 1 and 2 Oil Immersed Ex o IS 7693 Zone 1 and 2 IEC Increased Safety Ex e IS/IEC * Zone 2 Non-Sparking n IS/IEC Zone 2 Note *: Internationally the type of protection Ex e is allowed in Zone 1 areas per IEC and IEC As per Indian Standard IS 5571 Guide for Selection and Installation of Electrical Equipment in Hazardous Areas (other than Mines) an associated terminal housing of type Ex e is allowed in Zone 1. However other Ex e apparatus is not allowed in Zone 1, and is allowed in Zone 2 only. Table 3: Equipment type of protection and hazardous location suitability Page 16 Ex-Magazine 2011

6 > Type of Protection Flameproof Enclosures d Flameproof equipment having flange joints must be installed in such a way that there is no solid structural obstacle near the flange joints. The minimum clearance shall comply with the standard requirements. Flameproof joints shall be protected against corrosion and ingress of water. Silicon grease may be used for protection of flange joints from corrosion. The flange joint should not be tapped for preventing ingress of water. The use of gaskets is allowed only when permitted by the equipment documentation. > Terminals All terminals in equipment with type of protection Ex e, Ex i, or Ex n shall be either individually certified or certified along with the equipment. Hazardous areas like coal mines and other mines are covered under the standard IS Guide for the selection of electrical and electronic equipment for coalmines and IS Code of practice for installation and maintenance of Ex equipment in mines. The installations in hazardous locations have to be approved by statutory authorities like the Petroleum and Explosives Safety Organisation (PESO), the Director General of Mines Safety (DGMS) or the Director General of Factory Advise Service and Labor Institute (DGFASLI), depending on the hazardous area. This is very often a complicated and time consuming process. Inspection and Maintenance of Equipment The basic inspection and maintenance requirements for electrical equipment used in hazardous location electrical equipment are covered in the Indian standard IS Code of practice for the selection, installation and maintenance of electrical apparatus for use in potentially explosive atmospheres (other than mining application or explosive processing manufacture. The current standards in India harmonized in this filed with international IEC standards are IS/IEC and IS/IEC Conclusion The Bureau of Indian Standards BIS needs to establish procedures and processes to adopt the IEC codes and standards without any change and loss of time as Indian Standards. It is not logical to review IEC codes and standards again, after they have been reviewed, commented, changed and voted on at the IEC level. The role of the code and standards making committee ET 22 should be to review the draft IEC standards, and the BIS should actively represent the recommendations of ET 22 at the IEC level and meetings. Once the IEC code and standard has been revised and adopted, it should be adopted as Indian Standard without any change and delay, thus bringing Indian Standards at par with International Standards. It is important for India to adopt the international IEC standards and the processes and procedures of the IECEx conformity as- sessment scheme (IECEx scheme). It is essential that the IEC codes and standards pertaining to explosion protected electrical equipment and related aspects are adopted as as-is Indian standards. This would ensure the acceptance of Indian products at a level with international products, and would also remove disadvantage for Indian manufacturers competing in the world market, which then creates a level playing field for Indian manufacturers with international manufacturers and vice-versa. This also would allow the Bureau of Indian Standards as member of the IEC to issue a BIS marking license to foreign manufacturers and their Indian subsidiaries and facilities based on the available IECEx test report, certificate and quality assessment report QAR. There is no point of re-testing the same product again to comply with the IS/IEC series of Indian standards. Furthermore the guidelines for statutory approval of installations in hazardous areas need to be updated and streamlined to comply with IEC This should be done jointly between BIS, users, authorities having jurisdiction, third party inspection agencies and equipment manufacturers. Ex-Magazine 2011 Page 17

7 Design, testing, certification, installation & maintenance in India IS Standard Title of Indian Standard IEC Standard Title of IEC Standard Status IS/IEC : 2004 Electrical apparatus for explosive gas atmospheres General Requirements IEC Ed /10 Part 0 : Equipments-General Requirements IS/IEC : 2007 Part 1: Euipment Protection by Flameproof Enclosures d IEC Ed /04 Part1-Equipment Protection by Flameproof Enclosures d IS / IEC : 2002 Electrical Apparatus for explosive gas atmospheres Flameproof enclosures d -Method of test for ascertainment of maximum experimental safe gap (First Revision) IEC :2002/07 now merged with IEC :2010 Electrical apparatus for explosive gas atmospheres Part 1-1: Flameproof enclosures d : Method of test for ascertainment of maximum experimental safe gap 2002 Version IS / IEC : 2007 Part 2: Equipment Protection by Pressurized enclosures p IEC Ed /02 Part 2: Equipment Protection by Pressurised enclosures p IS 7820: 2004/ IEC : 1975 Electrical Apparatus for explosive gas atmospheres: Method of test for ignition temperature IEC :1975 now merged with IEC :2010 Electrical apparatus for explosive gas atmospheres Part 4: Method of test for ignition temperature 1975 Version IS / IEC :1997 Sand filled electrical apparatus for use in explosive atmospheres IEC Ed /03 Explosive Atmospheres Part 5: Equipment Protection by Powder filling q IS / IEC : 1995 Electrical Apparatus for explosive gas atmospheres Oil immersion o IEC Ed /03 Part 6: Equipment Protection by Oil immersion o IS / IEC Equipment Protection by Increased Safety e IEC Ed /07 Part 7: Equipment Protection by Increased safety e IS Classification of hazardous areas (other than mines) having flammable gases & vapours for electrical installation (Third Revision) IEC Ed /12 Explosive gas atmospheres Part 10-1: Classification of areas Explosive gas atmopheres IEC Code printed with national differences IEC Ed /04 Explosive gas atmospheres Part 10-2: Classification of areas Combustistible dust atmospheres Under Adoption IS / IEC Electrical Apparatus for explosive gas atmospheres Intrinsic Safety i IEC Ed /06 Part 11: Equipment protection by intrinsic safety i IS Classification of flammable gases & vapours with air according to their maximum experimental safe gaps and minimum igniting currents IEC :1978 now merged with IEC :2010 Electrical apparatus for explosive gas atmospheres Part 12: Classification of mixtures of vapours with air according to their maximum experimental safe gaps and minimum igniting currents 1978 Version IS 11064: 1984 Guide for construction & use of rooms or buildings protected by pressurization for installation of electrical apparatus for explosive gas atmospheres IEC Ed1 2010/10 Part 13: Equipment protection by pressurized room p 1982 Version IS Guide for selection & installation of electrical equipment for hazardous area (other than mines) (third Revision) IEC Ed /12 Explosive Atmospheres Part 14: Electrical installations -Design, Selection & Erection IEC Code printed with national differences IS/IEC Electrical Apparatus for explosive gas atmospheres Part 15: Construction, Test & Marking of Type of protection n Electrical Apparatus IEC Ed /01 Part 15: Equipment protection by type of protection n 2005 Version IS/IEC Electrical Apparatus for explosive gas atmospheres Part 16: Artificial Ventilation for the protection of analyzer houses IEC Ed /05 Electrical Apparatus for explosive gas atmospheres Part 16: Artificial Ventilation for the protection of analyzer houses IS (Part 1) 1992 Code of practice for the selection, installation & maintenance of electrical apparatus for use in potentially explosive atmospheres (other than mining application or explosive processing manufacture) Part 1: General recommendation Withdrawn IS/IEC IS/ IEC IS/IEC IEC/IS IS/IEC Explosive Atmospheres (Other than mines & explosives) Part 17: Electrical Installations - Inspection & Maintenance Electrical Apparatus for explosive gas atmospheres Part 18: Construction, Test & Marking of Type of protection m Electrical Apparatus Part 19: Equipment. Repair, overhaul & reclamation Electrical Apparatus for explosive gas atmospheres Part 20: Data for flammable gases & vapours relating to use of electrical apparatus Electrical Apparatus for explosive gas atmospheres Part 25: Intrinsically Safe Systems IEC Ed /08 IEC Ed /05 IEC Ed /11 IEC Ed1 2010/01 IEC Ed /02 IEC Ed /08 IEC Ed /01 Explosive Atmospheres Part 17: Electrical installations inspection & maintenance Part 18: Equipment protection by encapsulation m Part 19: Equipment. Repair, overhaul & reclamation Part 20-1: Material characteristics for gas and vapour classification Test methods and data Part 25: Intrinsically safe electrical systems Part 26: Equipment with Equipment Protection Level (EPL) Ga Part 27: Field bus intrinsically safe concept (FISCO) 2006 Version under printing 2006 Version 1996 Version 2003 Version Page 18 Ex-Magazine 2011

8 IS Standard Title of Indian Standard IEC Standard Title of IEC Standard Status IEC Ed /08 Part 28: Protection of Equipments & transmission system using optical radiation IEC Ed /08 IEC Ed /08 Explosive Atmospheres Part 29-1: Gas Detectors-Performance requirements of detectors for flammable gases Explosive Atmospheres Part 29-2: Gas Detectors-Selection, installation, use and maintenance of detectors for flammable gases and oxygen IEC Ed /11 Part 29-4: Gas detectors - Performance requirements of open path detectors for flammable gases To be adopted IS (Part 1) 2000 Resistance trace heating in potentially explosive atmospheres Part 1: General & testing requirements IEC Ed1 2007/01 Part 30-1: Electrical resistance trace heating General & testing requirements IS (Part 2) 2000 Resistance trace heating in potentially explosive atmospheres Part 2: Informative application guide for design, installation and maintenance IEC Ed /01 IEC Ed /11 Part 30-2: Electrical resistance trace heating Application guide for design, installation & maintenance : Part 31: Equipment Dust Ignition Protection by enclosure t IS Miners Cap lamp assemblies (incorporating lead acid type batteries) IS Exploders IS Guide for selection of electrical & electronic equipment for coal mines IEC Ed /10 IEC Ed /10 Cap lights for use in mines susceptible to firedamp Part 1: General requirement Construction & testing in relation to risk of explosion Cap lights for use in mines susceptible to firedamp Part 2: Performance & other safety related matters To be adopted To be adopted Under Revision IS IS (Part 1) 1996 Code of Practice for installation & maintenance of electrical equipment in mines Electrical apparatus with protection by enclosure for use in the presence of combustible dusts: Part 1 Specification for apparatus Under Revision To be withdrawn IEC Ed /07* dust Part 0: General Requirements IS (Part 1) 1988 Method of determining the minimum ignition temperature of dusts Part 1: Dust layer on a heated surface at a constant temperature IEC Ed /12 dusts: Part 2: Test methods- Section 1: Method of determining the minimum ignition temperature of dust IEC/ TS Ed /08* dusts: Part 2: Test methods- Section 2: Method of determining the electrical resistivity of dust in layers IS (Part 2) 1988 IS/IEC : 2005 IS 15142:2002 IS (Part 2) 1997 IS/IEC : 2004 Method of determining the minimum ignition temperature of dusts Part 2: Dust cloud in a furnace at a constant temperature dusts: Part 11: Protection by intrinsic safety id Guide to the use of Electrical Apparatus for potentially explosive atmospheres in the presence of combustible dust Electrical apparatus with protection by enclosure for use in the presence of combustible dusts: Part 2 Guide to selection, installation & maintenance dusts Part 14: Selection & Installation IEC Ed /09* IEC Ed /03 IEC Ed /10 IEC Ed /07* IEC Ed /01* dusts: Part 2: Test methods- Section 3: Method of determining the minimum ignition energy of dust / air mixture dusts: Part 4: Type of protection pd dusts: Part 11: Protection by intrinsic safety id dust part 14: Selection & Installation dusts Part 17: Inspection & maintenance of electrical installations in hazarous areas To be withdrawn To be withdrawn 2004 version printed as IS Withdrawn by IEC IS/IEC : 2004 dusts: Part 18: Protection by encapsulation md IEC Ed /08* * Note: In future the series of IEC Standards IEC will be merged with the relevant standards of series IEC dust Part 18: Protection by encapsulation md 2004 version printed as IS Table 4: List of Indian and IEC standards for hazardous areas Ex-Magazine 2011 Page 19