First mining

Mining originated in ancient times along with the emergence of human society and has been developing for several millennia. It can be said that the very formation of man is connected with mining: it began with the manufacture of tools, and mining provided the material for these tools, and every next step of mankind and the entire modern civilization is unthinkable without mining - a supplier of raw materials.

The early periods of mining history took place in different regions at different times — the most reliable and earliest archaeological sources of Stone Age cultures were found in Africa, Europe, Asia, copper and bronze — in the Mediterranean countries, in Asia Minor, the Balkans and the Alps, the Urals and Kazakhstan, the period of iron tools — in the countries of the ancient world, Asia Minor and Central Asia, Transcaucasia, Western Europe, China, Japan. The emergence of mining and crafts, their development into the mining industry for the first time occurs in the countries of the Far East, the ancient world, Western Europe, etc.

It is known that among the first minerals mined by man were silicon, various minerals, rocks such as jasper, obsidian, hornstone, slate, quartzite, dolomite, as well as mineral paints, for example, ochre.

Fundamental innovations corresponded to each stage of mining evolution. This was due to the improvement of tools and mining technologies, an increase in the number of types of minerals extracted from the bowels of the Earth.

The primitive gathering of stone from the surface of the Earth with the advent of the first tools, such as stone (figure 1) and animal horns (figure 2), was replaced by its extraction from the Ground using pits and ledges.

In the Neolithic era, with the advent of crafts, including the manufacture of stone tools (figure 3), hammers, pickaxes, hoes, picks, wedges for mining appeared. The most ancient mining is being formed as a system of techniques for using these tools. For the extraction of flint, pits, ditches, niches in steep river banks and underground workings are dug and gradually replaced by targeted mining from a certain depth.

Natural ventilation

At first, the workings had a wide variety of shapes and resembled animal manholes. Over time, the workings become more correct, more regular, and vertical shafts become the most widespread (figure 4), since they provided the shortest access to the deposit and, consequently, the least amount of work. It is believed that inclined shafts appeared simultaneously with vertical ones, since they allowed, without any devices, to exit the mine and carry out the cargo. The mines with two opening workings, in fact, became the prototype of the entire subsequent development of mining, up to the present time, two exits provided greater safety and natural ventilation.

In the Stone Age, with the development of copper ore mining, the fire method of work began to be applied. Due to the high strength of the ore bodies, which make it much more difficult to excavate them with simple tools. The fire method consisted in artificially weakening the strength of the rock mass by "burning" (bonfire y slaughter) and abrupt cooling of heated rocks with water, which led to cracking of the massif, wooden wedges were hammered into the cracks formed with stone sledgehammers. Then the wedges were wetted, and when they swelled, they tore the rock blocks from the array. Special "chimneys" are made in the trunks to remove smoke (figure 5).

At this stage, mining operations arise to extract large stone monoliths for the manufacture of building blocks, obelisks, megaliths, astronomical landmarks, etc. Large open-pit mining of strong limestones and sandstones. This activity reached its largest scale in Ancient Egypt during the construction of the pyramids.

Along with the large-scale extraction of stone materials, placers are being developed with the capture of gold sand using spread animal skins, as well as primitive extraction of oil and bitumen from open natural reservoirs.

The development of mine workings, the complication of their shape, length and maintenance time has set the miners the task of ensuring their safety. To protect the mine from collapse, supports were built from blocks of stone or wooden struts were used. For the same purposes, the roof of the mining was given a vaulted, arched or pointed shape. Ventilation was carried out by means of special additional vertical workings, which were carried out at different levels. To prevent flooding of the mines by heavy rains, protective dams were built near the trunk. Groundwater was collected in pits-catchment basins, from which water was bailed out with leather or birch bark buckets. Splinters and oil lamps are used to illuminate workplaces.

The penetration of man into the underworld meant his entry into the struggle with the forces of nature, which has not stopped for a moment to the present day. Thus, with the increase in underground coal mining and the deepening of mines, the fact of the presence of certain gas accumulations in the mine air, which lead to sudden explosions, is established (figure 6).

• The accident at the «Golden Donkey» mine in the town of Zloty Stock in Poland in 1550, which killed 59 people,

• Explosion in the «Gates head (Stony Flatt)» mine in County Durham in the north of England in 1705, which killed 30 people;

• Explosion in the «Almv No. 2» mine in Almy, Uintah County, Wyoming, USA in 1881 killed 38 people.

These are some of the first, but by no means the only cases of explosions that occurred during the extraction of minerals in underground mine workings in Europe and the United States of America. It was there, in the dark mines lit only by splinters and candles, that the history of explosion protection began.

The cause of all these tragic events is natural gas – methane, which can burn and explode in contact with open fire and coal dust. The ignition of methane was usually followed by a much stronger explosion of dust.

The first ways to control methane

At the dawn of mining, they tried to deal with dangerous gas by means of a kind of ventilation of mine workings. A short horizontal excavation was made in the upper part of the mine shaft, in which the flame of the fire was maintained. The flow of hot air coming to the surface created a draft, as in a household furnace, and it pulled out polluted mine air (figure 7).

Such ventilation methods were not reliable and its burning was proposed as a control against methane. To do this, additional workings were cut in the coal mining area - the gas spread through them and mixed with air. Then the resulting mixture must be ignited, after which it exploded. To perform risky work, a special person was hired - a "Scorcher", in different countries he was called a "Fireman", "Penitent" or "Gunner". The "Scorcher" put on wet clothes and a mask with a glass window to protect his eyes, picked up a long pole with a torch made of tow wrapped on a stick and soaked in fuel oil, lay down, crawled into the mine and ignited methane, i.e. provoked an explosion. After that, mining operations could continue in a relatively safe mode. According to the safety rules that existed at that time, the supervision of the mine had to be held accountable for allowing miners to work without first burning gas in the faces. Such a struggle with gas was usually carried out between shifts, when there were no miners in the pits (figure 8).

The profession of a "Scorcher" disappeared only when canaries began to serve as indicators of the presence of gas in the mine, the bird felt the effects of gas much earlier than a person. The silence or loss of consciousness of the canary warned the miners that there was a large amount of gas in the air and it was necessary to leave the mine quickly (figure 9).

Iinteresting fact: Miners used canaries as gas detectors until 1996.

All these measures were not reliable at all, because there was still an open fire underground - splinters, candles, oil lamps, torches, which illuminated the workings, were the main cause of the methane explosion. Lamps that could work in a methane environment were required.

The invention of safety lamps

One of the first safe lamps for mines was developed in 1815 by the outstanding English chemist Humphrey Davy. In it, a metal mesh covered the flame from direct contact with the mine air and dissipated heat (figure 10). The use of the Davy lamp can be considered the first success in the fight against coal methane. Moreover, knowing what explosions in mines could lead to, Davy nobly refused to patent his invention, so his safety lamps began to be produced all over the world and saved a large number of lives.

The Davy lamp reduced the likelihood of explosions in mines, but did not prevent them, because it had some disadvantages and as a result underwent significant improvements:

• The lamp was equipped with a cylinder made of thick glass;

• Gasoline was used as a lighting material instead of oil, which gave more light;

• Gasoline was not just poured into the lamp in liquid form, but the lamp reservoir was filled with cotton wool, which absorbed gasoline, and gradually gave it to the wick;

• A special shutter has been developed that prevents the worker from opening the lamp in the mine;

• If the lamp was accidentally extinguished, it was lit with a special flint that gave a spark inside the lamp.

Interesting fact: The modern analogue of the Davy lamp is used in torches for the Olympic flame.

The disadvantages of the Davy lamp prompted other inventors to develop lamps of a more advanced design. Among such lamps, it is worth paying attention to the lamp developed in 1840 in Belgium by Mathieu-Louis Museler. The Museler lamp had the following advantages:

• It was brighter than its predecessors, which allowed it to be kept at some distance from the work area, 

• Had two grids – horizontal and vertical , and when one was broken, the other remained intact,

• The mesh did not come into contact with oil, which means that only dry dust could settle on it,

• Quickly extinguished with increasing gas concentration,

• The air flow came from above, not from the sides.

Also, a special place among the first safe mining lamps is occupied by the Karl Wolf lamp, developed at the end of the XIX century, which combined in its design many successful developments made by other inventors. In its design, a safety metal mesh was provided, as in the Davy lamp, a glass cylinder around the flame, a metal hood, and it also had a lower air supply. Additionally, it was equipped with a shutter that could only be opened with a magnet weighing more than 10 kg, thus, workers could not open it directly in the mine, unwittingly causing explosions (figure 11).

It is noteworthy that with the Wolf Lamp, the miners not only illuminated their way, but also determined the gas level in the mine. First, the flame of the lamp was reduced to a barely noticeable flame, then it was carefully brought to the ceiling of the shaft, where gas usually accumulates. If an elongated bluish glow formed around the flame, called a halo, it means that the concentration of gas in this place was dangerous.

Interesting fact: Despite the presence of modern electric lighting in the mines, workers continued to use the prototype of the Wolf lamp until the middle of the 20th century.

Looking back, we can confidently say that the invention of safety lamps for coal mines, to the creation of which outstanding inventors such as Humphrey Davy, Carl Wolf, Mathieu-Louis Mueseler and many others, not mentioned in this article, had a huge impact on the entire course of the industrial revolution. Since the beginning of the 19th century, coal mining has been carried out in many European countries and in the United States, and the use of safe lighting has ensured a significant increase in its production. In a short time, coal has become not only the most important raw material for the development of metallurgy, but also the main source of energy in industry and transport, and even in everyday life.

The intensive development of the coal mining industry stimulated the process of mechanization of mining and gave impetus to the development of mining engineering, which in turn made it possible to develop deeper, and therefore longer, mining operations. As a result, the flaming mine lamps ceased to meet the new conditions, neither in terms of light intensity nor in terms of safety. At a new stage in the development of the coal industry, the task of lighting mine workings was solved by switching to electric lamps. At the same time, the electrification of mines has posed new challenges to explosion safety.

The development of technologies for explosion-proof equipment at the beginning of the XX century

Shortly after the start of the use of electricity in coal mines, it was discovered that stationary electrical equipment such as lighting, alarm and communication systems or electric motors could lead to a deadly explosion no less than flame lamps that have already become history.

So, in 1913, a powerful explosion occurred at the «Universal» coal mine near the town of Senghenydd in England, which killed 439 miners (Figure 12). The most likely cause of the methane explosion at the beginning of the accident is considered to be a spark from bare wires used in the alarm system. At the beginning of the 20th century, the electrical alarm system in the mine consisted of two parallel bare wires running along the shafts, which allowed any miner who wanted to report a problem to the surface to do so by touching two wires with a metal tool for a moment.

And again, as more than a century ago, scientists and inventors faced the task of explosion safety in mining mines. The most significant studies were conducted in countries with developed mining industries, mainly in England, Germany and the USA. It is worth noting that in the XX century, along with electrical and explosion safety technologies, legislation in this area began to actively develop.

In Germany, where the production of electrical devices was already well established, significant technical developments were carried out by mining engineer Karl Beiling. His research mainly focused on electrical devices such as electric motors, transformers and switches with various types of housings. The results of his research concerned several protection methods, some of which are currently combined into one type of explosion protection - "flameproof enclosures" and have the designation Ex d.

Interesting fact: The letter "d" in the name of this type of explosion protection comes from the German "druckfeste Kapselung".

In 1912, the association of electrical engineers of Germany "Verband Deutscher Elektrotechniker" (VDE), based on various studies conducted by Karl Beiling, issued the VDE 0170 standard regulating the safe operation of products in mines dangerous for mine gas.

Later, in 1935, the VDE 0165 standard was approved, which extended not only to mines, but also to other "hazardous production" areas. In 1938, a fundamental change appeared in the above standards, separating the requirements for the installation of equipment (VDE 0165) and the requirements for its design (VDE 0170 / 0171). When updating the VDE 0170/0171 standard in 1943, it included requirements not only for the design of equipment but also for technical documentation for this equipment. Mandatory marking of explosion-proof equipment manufactured according to these standards with the Ex symbol inscribed in a circle was also introduced.

Also, a German legislative decree established that manufacturers of explosion-proof equipment are required to comply with VDE standards, and enterprises that have explosion-hazardous areas must determine the size of these hazardous areas.

Standards for the design of equipment included such types of explosion protection as explosion-proof enclosures, immersion in oil and increased safety. The components must be designed in such a way that they are protected from explosions and placed in industrial-type enclosures that are resistant to atmospheric influences. This led to the development of explosion-proof components installed inside increased safety housings.

In parallel with Germany, technical and regulatory developments in the field of explosion protection were carried out in England.

In 1929, the The British Standards Institution issued the BS 229-1929 explosion-proof equipment standard. The first expert opinions (now called the "Certificate of Conformity") on explosion-proof equipment were issued, in particular, by the Sheffield University. In 1922-1931, about 285 expert opinions were issued.

Since the beginning of the twentieth century, in addition to protection with explosion-proof shells, the idea has spread about the possibility of creating electrical devices that are safe from the point of view of the risk of ignition of an explosion by limiting the electrical energy received mainly at very low voltage (12 V). This concept was only applicable to devices with limited power, such as sound alarms or transmitters. The disaster that occurred in the previously mentioned «Universal» coal mine near the town of Senghenydd due to a spark prompted an in-depth study of this type of explosion protection.

This led to the development of what would later be called intrinsic safety, and was reflected in the British standard BS 1259:1945. This standard contained about eleven pages and focused on electromechanical components such as relays and solenoids, since semiconductor electronics appeared later.

Along with Germany and England, the development of regulatory documents on explosion protection was carried out in other European countries, for example, in Poland, the first standards for explosion-proof equipment PNE-17:1929 were issued in 1929. They were developed by the Polish Electricians Association (SEP) in cooperation with the Czechoslovak Electrotechnicians Association 

At the beginning of the 20th century, technology and legislation in the field of explosion protection were developing in the United States. First, in 1910, the U.S. Congress established the "Bureau of Mines", whose purpose was to study the market and set standards to ensure safe operation in mines.

In 1911, standards were developed for the design of explosion-proof electric motors and tests to evaluate their effectiveness. But the first edition of the standard turned out to be too vague and meager, and over time it was repeatedly revised and expanded. In this standard, devices were classified into three types. The first type included devices that spark during normal operation (motors, fuses, switches); the second type included devices that spark in case of failure (batteries, terminals); The third one includes devices that can be operated even outside an explosive zone (for example, a plug). Devices sparking during normal operation had to be placed in explosion-proof enclosures.

In 1929, the Bureau of Mines issued the document «Testing of Mine-Type Electrical Equipment for Tolerance». This document describes the test equipment and the test methods used to assess the conformity of the equipment to its intended purpose. In addition to the tests, a detailed inspection of the equipment parts, a thorough check of compliance with the drawings and specifications should be carried out. These drawings are the main document for the equipment under test and therefore must be complete and describe its design in detail.

For the first time in the USA, attention was paid to the classification of dangerous places. So in 1923, the National Electrical Code of the United States (NEC) adopted a new article called «Extra-Hazardous Locations». This article considered the premises in which gases, liquids, mixtures or other flammable substances were produced, used or stored. The use of equipment capable of creating an arc or sparks was prohibited unless it was protected by a housing approved for this purpose. In 1931, dangerous places were classified, and included Class I, Class II, etc. Also, this document contained provisions that all electrical wiring laid in particularly dangerous places should be made in protective metal boxes or armored cable. The luminaires must be equipped with vapor-proof caps and have protective enclosures. Switches and motors suitable for use were forbidden to be installed near hoods or ventilation pipes.

Three main ways of providing explosion protection have been used and developed in different countries:

• containing the explosion to the area directly surrounding the electrical circuit, now called flameproof enclosure «d»,

• precluding an explosive mixture from reaching the electrical circuit, now it is protection by pressurized enclosures «p», protection by oil immersion «o», protection by powder filling «q»,

• limiting the energy, intrinsic safety «i».

The general approaches were the same, but there was a difference in some design details. For example, the method of inserting a cable into an explosion-proof shell. So in Germany, the cable was inserted into an explosion-proof enclosure through high-security enclosures, and in France special cables could be used directly in explosion-proof enclosures, and in the UK an explosion protection system was used for this.

Such a difference in requirements indicated the need for harmonization of regulations in the field of explosion protection between countries.

The formation of legislation on explosion-proof equipment

The next round of development of legislation in the field of explosion protection occurred in the second half of the 20th century, this was due to the fact that the European Community was created in Europe, the purpose of which was to create a free trade area in Europe. In this regard, the European Committee for Electrotechnical Standardization (CENELEC) was established.

In 1972, the set of European standards EN 50014 - EN 50020 was published, which described equipment for use in explosive atmospheres.

In 1975, the first EU directive on equipment used in hazardous areas, known as the «Ex Protection Directive», was published (Figure 13).

In 1976, the Directive on the Harmonization of the Laws of the participating Countries with regard to electrical equipment intended for Use in Potentially Explosive Atmospheres (76/117/EEC) was published. This directive was subsequently changed, but concerned only electrical equipment.

In 1994, a new Directive 94/9/EC (ATEX) was published, which applied to all types of equipment, both electrical and non-electrical.

Interesting fact: ATEX got its name from the French name of Directive 94/9/EC «Appareils destinés à être utilisés en ATmospheres EXplosibles», which translates as "Equipment intended for use in explosive atmospheres".

Along with the pan-European legislation on explosion protection, international legislation on explosion protection has also developed.

In 1948, the Technical Committee TC31 (Equipment for Explosive Environments) was established within the framework of the International Electrotechnical Commission (IEC). The area of activity of TC31 is the development and maintenance of international standards for equipment intended for use where there is a risk of the presence of explosive atmospheres consisting of gases, vapors, fog or combustible dust

Throughout its activity, TC31 has prepared international standards of the IEC 60079 series, which provide the explosion-proof industry with the most stringent requirements covering the entire life cycle of explosion-proof equipment, from design and production to installation, maintenance and repair. They also relate to the competence of personnel working in hazardous areas. Moreover, in 2016, the ISO 80079 series of standards concerning non-electrical equipment was published.

The IEC established the IECEx certification system for equipment intended for use in explosive atmospheres in accordance with IEC 60079 series standards (Figure 14). In 1996, the first IECEx meeting was held. With the establishment of the certification system, IEC has strengthened its presence and growing influence in this sector. Since then, industry, regulators and Governments have been provided with tools to ensure that equipment used in hazardous areas actually meets the strict requirements set out in IEC 60079 standards.

In accordance with the agreement between the European Committee for Electrotechnical Standardization CENELEC and the International Electrotechnical Commission  IEC, international standards for electrical equipment are generally accepted by CENELEC unchanged. The EN 50014 ff series, which defines the requirements for equipment operating in explosive atmospheres, is being replaced by the EN 60079 series (internationally IEC 60079).

The basic principles of explosion protection are the same all over the world. However, methods and systems have been developed in North America that differ significantly from the IEC system.

Differences can be noted in the classification of hazardous areas. In North America, zones are divided into classes: I – combustible gases, vapors or mists, II – dust and III – fibers or lint, at the same time, each of the classes has a division depending on the probability or duration of the presence of these dangerous substances: Division 1 and Division 2.

In 1996, NEC Article 505 was amended, according to which the IEC classification system for explosive zones was also introduced for Class I. This amendment allows you to choose the optimal system in terms of technology and economic efficiency. In 2005, corresponding changes were also introduced for Class II, i.e. zones 20, 21 and 22 were introduced for zones with combustible dust.

The IEC classification of hazardous areas was also introduced in Canada, for Class I in 1988, for Class II in 2015. All newly installed systems should be classified according to these changes.

Interesting fact: The traditional North American classification system divides combustible gases, vapors, mists and liquids of Class I into groups according to gas type A, B, C and D. The letter A denotes the most dangerous group of gases (Acetylene), while in the IEC classification the most dangerous group is group IIC (Acetylene).

In the USA, National Electrical Code (NEC) apply to electrical equipment used in hazardous production facilities, and in Canada, Canadian Electrical Code (CEC). They define the rules for the installation of electrical equipment in all areas and contain references to the standards of other organizations regulating the technical requirements for the design and installation of appropriate equipment.

In addition, in North America, the design and testing of explosion-proof electrical systems and equipment is regulated by various standards and regulations. In the USA, these are mainly the standards of the International Society for Measurement and Control (ISA), the Underwriters Laboratories Inc. (UL) and the Factory Mutual Research Corporation (FM) (Figure 15). In Canada, the standards of the Canadian Standards Association (CSA) are applied .

Currently, the United States has also adopted 13 IEC standards, which are used in various industries where explosive zones are present, except for the mining industry. In particular, in the US mining industry, only 2 types of explosion protection are allowed – use of explosion-proof enclosures (XP boxes) and 2-fault Intrinsic Safety (IS).

To date, despite some national differences in approaches to the classification of explosive zones, requirements for the design of equipment and methods of ensuring explosion protection, the process of harmonization of regulations is actively continuing.

For example, one IECEx certificate is currently sufficient for the international sale of explosion-proof equipment in Australia, New Zealand, Singapore and Israel. An additional national certificate is not required. In Europe, only the additional ATEX marking and the corresponding ATEX certificate are required. In other regions, including the USA, IEC standards are applied with some deviations. There is also active research in the USA on the adoption of IEC standards for the mining industry.

Moreover, IECEx has been approved by the United Nations through the United Nations Economic Commission for Europe (UNECE) as a certification system for conformity assessment in hazardous areas. The aim of this collaboration is to ensure that IECEx certification provides real economic benefits by reducing wasteful duplication of testing and evaluation while maintaining the necessary level of safety for society.

Currently, there are 41 standards developed by IECEx and in accordance with which conformity assessment takes place, as well as 3 more standards that can be used for testing. A list of these standards can be found below.

In the future, it is likely that the IECEx certification system will be recognized worldwide and will provide everyone with access to modern reliable security technologies. IEC standards establish the most important principles for manufacturers of electrical and non-electrical equipment designed to operate in hazardous areas, ensuring its safety. The more manufacturers and buyers of explosion-proof equipment rely on IECEx standards and certification, and the more regulatory and legislative bodies use them as the basis of their legislation, the higher the safety will be where there is an explosion risk.

The following standards developed by IEC are currently in force:

1. IEC 60079-0 Part 0: Equipment - General requirements,

2. IEC 60079-1 Part 1: Equipment protection by flameproof enclosures «d»,

3. IEC 60079-2 Part 2: Equipment protection by pressurized enclosures «p»,

4. IEC 60079-5 Part 5: Equipment protection by powder filling «q»,

5. IEC 60079-6 Part 6: Equipment protection by oil immersion «o»,

6. IEC 60079-7 Part 7: Equipment protection by increased safety «e»,

7. IEC 60079-10-1 Part 10-1: Classification of areas - Explosive gas atmospheres,

8. IEC 60079-10-2 Part 10-2: Classification of areas - Explosive dust atmospheres,

9. IEC 60079-11 Part 11: Equipment protection by intrinsic safety «i»,

10. IEC 60079-13 Part 13: Equipment protection by pressurized room "p" and artificially ventilated room «v»,

11. IEC 60079-14 Part 14: Electrical installations design, selection and erection,

12. IEC 60079-15 Part 15: Equipment protection by type of protection «n»,

13. IEC 60079-16 Part 16: Artificial ventilation for the protection of analyser (s) houses,

14. IEC 60079-17 Part 17: Electrical installations inspection and maintenance,

15. IEC 60079-18 Part 18: Equipment protection by encapsulation «m»,

16. IEC 60079-19 Part 19: Equipment repair, overhaul and reclamation,

17. IEC 60079-25 Part 25: Intrinsically safe electrical systems,

18. IEC 60079-26 Part 26: Equipment with equipment protection level (EPL) Ga,

19. IEC 60079-28 Part 28: Protection of equipment and transmission systems using optical radiation,

20. IEC 60079-29-1 Part 29-1: Gas detectors - Performance requirements of detectors for flammable gases,

21. IEC 60079-29-2 Part 29-2: Gas detectors - Selection, installation, use and maintenance of detectors for flammable gas and oxygen,

22. IEC 60079-29-4 Part 29-4: Gas detectors - Performance requirements of open path detectors for flammable gases,

23. IEC 60079-30-1 Part 30-1: Electrical resistance trace heating - General and testing requirements,

24. IEC/IEEE 60079-30-1 Part 30-1: Electrical resistance trace heating - General and testing requirements,

25. IEC 60079-31 Part 31: Equipment dust ignition protection by enclosure «t»,

26. IEC 60079-33 Part 33: Equipment protection by special protection «s» (Часть 33. Оборудование со специальным видом взрывозащиты «s»),

27. IEC 60079-35-1 Part 35-1: Caplights for use in mines susceptible to firedamp - General requirements - Construction and testing in relation to the risk of explosion,

28. IEC 60079-35-2 Part 35-2: Caplights for use in mines susceptible to firedamp – Performance,

29. IEC/TS 60079-39 Part 39: Intrinsically safe systems with electronically controlled spark duration limitation,

30. IEC/TS 60079-40 Part 40: Requirements for process sealing between flammable process fluids and electrical systems,

31. IEC TS 60079-44 Part 44: Personal competence,

32. IEC TS 60079-48 Part 48: Portable or Personal Electronic Equipment – Guide for the use of equipment without a certificate for use in Hazardous Areas,

33. IEC/TS 60079-46 Edition 1 Explosive atmospheres - Part 46: Equipment assemblies,

34. IEC/TS 60079-47 Explosive atmospheres – Part 47: Equipment protection by 2-wire intrinsically safe Ethernet concept (2-WISE),

35. IEC 62784 Vacuum cleaners and dust extractors providing equipment protection level Dc for the collection of combustible dusts - Particular requirements,

36. IEC 62990-1 Workplace atmospheres – Part 1: Gas detectors – Performance requirements of detectors for toxic gases,

37. ISO/IEC 80079-34 Part 34: Application of quality systems for equipment manufacture,

38. ISO 80079-36 Part 36: Non-electrical equipment for explosive atmospheres - Basic method and requirements,

39. ISO 80079-37 Part 37: Non-electrical equipment for explosive atmospheres - Non electrical type of protection constructional safety «c», control of ignition source «b», liquid immersion «k»,

40. ISO/IEC 80079-49 Part 49: Flame arresters – Performance requirements, test methods and limits for use,

41. IECEx OD 290 Hydrogen.

The following standards can be used for testing, but not for issuing an IECEx certificate of conformity:

1. IEC/TS 60079-32-1 Edition 1.0 Explosive atmospheres - Part 32-1: Electrostatic Hazards – Guidance,

2. IEC 60079-32-2 Edition 2.0 Explosive atmospheres - Part 32-2: Electrostatics hazards – Tests,

3. IEC/TS 60079-42 Explosive atmospheres- Electrical safety devices for the control of potential ignition sources for Ex-Equipment.

In addition to the standards in IECEx, there are also so-called operational documents (OD), which complement the Rules of Procedure and are intended for use in the IECEx certification system, for example, among such operational documents there are:

• OD 017 IECEx Drawing and documentation Guidance for IEC Ex Certification – for use by Manufacturers and ExTLS 

• OD 521 IECEx Scheme for Certification of Personnel Competence for Explosive Atmospheres - IECEx Recognised Training Provider Program. 

Operational documents are divided into the following categories:

• General - Applicable to more than one Scheme throughout the IECEx System

• Equipment  Certification Scheme - IECEx 02 – Rules of Procedure

• Certified Service Facilities Scheme - IECEx 03 - Rules of Procedure

• Conformity Mark Licensing System - IECEx 04 - Regulations

• Personnel Competencies Scheme - IECEx 05 - Rules of Procedure