| Written by Michal Wozniakowski-Zehenter

ATEX is the French term "ATmosphères EXplosibles"; it represents the standards and directives governing the equipment and protective systems intended for use in potentially explosive atmospheres. These regulations are critical to industries dealing with ignitable gases, dust, or vapours, including oil and gas, the chemical manufacturing sector, and, most importantly, mining. ATEX classification systems are an important way of ensuring the safety of equipment and personnel working in such hazardous conditions. It is one field that deals with explosive atmospheres, as extracting the minerals in mines often results in flammable gases, such as methane, and fine dust particles that may ignite under certain conditions. Thus, mining equipment should be in full compliance with strict safety regulations, including certification, to prevent accidents and huge explosions.
This article will outline the classification system in detail, what it means, and the corresponding symbols regarding mining equipment. The understanding of all these intricacies related to the standards is so crucial for any personnel engaged in the selection, operation, or maintenance of mining machinery. 
ATEX explained miner

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What is ATEX?

ATEX stands for the acronym of equipment used in an atmosphere with explosion hazards. It's not a standard or regulation, but a series of EU directives put forward to ensure safety within equipment usage in potentially explosive surroundings. This makes ATEX based on two important ATEX directives: Directive 2014/34/EU, called the ATEX Equipment Directive and Directive 1999/92/EC, which is called the ATEX Workplace Directive.

The new Directive 2014/34/EU was applicable to equipment and protective systems intended for use in explosive atmospheres within either electrical or mechanical equipment, and even control devices vitally important for their machinery in hazardous environments. The manufacturer must ensure that standards set forth allow for sales or use within the European Union. However, Directive 1999/92/EC addresses the obligations of employers. It ensures that workers in explosive atmospheres are adequately protected through appropriate risk assessment, maintenance of equipment, and periodic safety auditing. Together, these two directives form a broad framework for regulating equipment and measures related to safety within explosive atmospheres, where mining is one of the key sectors in which these rules apply most considerably (see also: Mining safety equipment).

 

Explosive Atmospheres in Mining

Generally, mining explosions are caused by the breaking and release of combustible gases such as methane and the presence of fine dust particles. Methane gas, being contained in most coal seams, may, during extraction, escape to form an explosive mixture upon combining with air. Moreover, coal dust or fine particles, under proper conditions, may ignite, causing terrible explosions.

These hazardous areas are then divided into zones, each identified by the possibility of forming an explosive atmosphere. ATEX certification uses such zone classification to base its degree and specification for safety measures and equipment. Even the minutest spark of any equipment in mines may ignite gases or dust and cause serious accidents. Because of that fact, ATEX compliance is not just a duty imposed by the law but also crucial for saving lives.

 

ATEX Explained: Zones and Categories

The ATEX classification system categorizes the equipment and environment into zones, which is important to ensure that the equipment is suitable for use in a potentially explosive atmosphere. The zoning system is based on the frequency and duration of an explosive atmosphere's occurrence.

Zone 0, 1, 2 for Gases and Vapors

Zone 0: An area in which an explosive atmosphere consisting of a mixture of air or gases, vapours, or mists is continuously present or for long periods. This represents the most hazardous classification. This may occur in mining where constant methane gas is near a coal seam.

Zone 1 is considered a place where an explosive atmosphere will probably occur in normal operation but not continuously. It would include areas around methane gas release points, such as ventilation shafts or mining equipment designed to cut through coal seams.

Zone 2 is one in which an explosive atmosphere is unlikely to occur in normal conditions, and if it occurs at all, then only for a short period. An example of such an area may be further away from gas release points in the mining tunnel, where methane gas could accumulate for short periods.

The dust environments similarly are classified but with a different numbering system. Zone 20 represents locations where a cloud of combustible dust is in the air continuously or for long periods. This would include a coal dust processing plant.

Zone 21 is where the cloud of dust is likely to occur during normal operations, such as around conveyor belts used in the transportation of coal.

Zone 22 is a location where the dust cloud formation isn't likely or would be in the air only for a very short period if it happens. That could be the most remote area in a mine where dust gathers occasionally, but a ventilation system would generally mitigate it.

ATEX

ATEX EQUIPMENT CATEGORIES

ATEX classification also categorizes equipment into groups based on the zone in which it can operate without causing a hazardous situation. These groups are referred to as Group I and Group II and each is divided into further categories.

Group I applies to equipment intended for underground mining and equipment intended for use in surface installations associated with underground mining or open-cast mining. This group is important to the mining industry since it categorizes equipment that must be intrinsically safe for use in environments where an explosive atmosphere often occurs. Equipment in Group I is further categorized into Category M1 and Category M2.

Category M1: Equipment in this category shall be designed to work safely even when an explosive atmosphere is continuously present. It should continue to operate even if a gas leak or explosion occurs. The equipment should be so designed that every safety mechanism incorporated within it works without fail under all conditions.

Category M2: This category includes equipment for use in explosive atmospheres that are less frequent. In such scenarios, the equipment can be turned off in case of an explosive atmosphere; however, this equipment needs to be strong enough and not allow any spark or hot surfaces that may ignite the gases or dust.

Whereas Group I is strictly for mining, Group II covers equipment used in other industries that deal with explosive atmospheres, such as oil refineries, chemical plants, and food processing. This category similarly groups equipment by zones where the operation is generally safe: Category 1 for Zone 0, 20; Category 2 for Zone 1, 21; and Category 3 for Zone 2, 22.

 

ATEX EXPLAINED: Markings and Symbols

ATEX-certified equipment bears markings that clearly define its use for specific zones and environments. These markings are key to the appropriate utilization of equipment within hazardous areas.

The CE mark must appear on any equipment sold into the European Union and ensures that the equipment meets all the relevant EU legislation, including the ATEX directives. In addition to the CE marking, the ATEX marking, a hexagon sign containing the letters "Ex," denotes your equipment will be safe to operate in a potentially hazardous explosive environment.

Group and Category Markings

Equipment for explosive atmospheres will be additionally marked with its group and category. Mining equipment, for example will be marked "I" for Group I and the category will also appear. A piece of equipment marked "I M1" is designed for continuous use in an explosive atmosphere (Category M1), and equipment marked "I M2" serves less frequent explosive atmospheres.

Protection Concepts and Gas/Dust Symbols

In addition to group and category markings, equipment is also marked by symbols indicating its level of protection against sparks, flames, or excessive heat. These are called protection concepts. For example, "d" indicates flameproof equipment, that is, equipment designed such that if an internal explosion were to occur, it would be contained without allowing flames or hot gases to be emitted.

Other protection concepts of electrical equipment include "ia" or "ib" for intrinsic safety; this implies that the equipment operates at low energy levels incapable of causing ignition. "e" would show increased safety, while "p" refers to pressurization-the maintenance of equipment under pressure to prevent ingress of explosive gases.

In dust environments, the equipment would be marked with either "D" for dust or "G" for gases. Mining machinery working in both types of atmosphere will very often bear a double marking, which ensures that the equipment is suitable for working in an atmosphere with the presence of both gases and dust particles.

Temperature Classes

Equipment will also be marked with a temperature class, or the maximum surface temperature it will reach. This is to prevent the equipment's surface temperatures from rising high enough to ignite gases or dust. Temperature classes range from T1 (450°C) to T6 (85°C), with the most stringent being T6, meaning the equipment cannot exceed 85°C.

Gas Groups and Dust Groups

It is also further categorized into gas and dust groups depending on the particular substance that can be handled by the equipment safely. Concerning the classification into gases, it may fall into Group IIA, IIB, or IIC, with IIC being the most dangerous category since the equipment will be able to handle highly explosive gases like hydrogen.

Dust Equipment Group Classification concerning dust falls into one of three groups: IIIA, IIIB, or IIIC. Group IIIA involves combustible flyings, while IIIB is applied to non-conductive dust, and IIIC for conductive dust, the most dangerous group concerning dust in most environments.

 

Importance of ATEX Certification to Mining

ATEX certification has a very important role in mining for many reasons. Explosive atmospheres pose an imminent danger in underground operations due to their high methane and coal dust content. Equipment bearing the certification by ATEX has been designed to be used safely within such an environment with the least chance of ignition or explosion. All miner technology that is used in mines, from drilling rigs to conveyor belts and ventilation systems, must also be according to ATEX standards since mining operations must not harm the workers or the environment. Non-compliance with these standards has been proven to have disastrous consequences, with results spanning between loss of life, equipment damage, or even environmental disasters.

 

FAQ

What does ATEX stand for, and how does it apply to mining equipment?

ATEX stands for "ATmosphères EXplosibles" and refers to the European Union directives that regulate the use of equipment in environments with potentially explosive atmospheres, such as those found in mining. In mining, where gases like methane and dust particles can easily ignite, ATEX certification ensures that equipment is designed to prevent any ignition sources. ATEX-compliant mining equipment is built to operate safely in areas where flammable substances are present, reducing the risk of explosions and protecting workers and operations.

How does ATEX classify hazardous zones in mining operations?

ATEX classifies hazardous zones based on the likelihood and duration of explosive atmospheres being present. In mining, these are divided into gas and dust zones. For gases, Zone 0 is the highest risk, where explosive gases are continuously present, while Zones 1 and 2 have progressively lower risks. Zone 20 is the most dangerous for dust, where combustible dust is present for long periods, with Zones 21 and 22 indicating decreasing hazard levels. ATEX certification ensures that mining equipment is suitable for use in the specific zone it is intended to operate in, ensuring maximum safety.

 

TAKEAWAY

ATEX regulations and classifications play a major role in ensuring the safety of equipment operating in explosive atmospheres, as well as the personnel working in those conditions. In mining, with the quite high risk of explosion both from gases and dust, following ATEX directives is not optional but binding. Understanding the system of classification according to ATEX, what symbols mean, and the importance of proper certification of equipment will go a long way for mining operations in minimizing the risks related to an explosive environment.

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Sources:

(1) https://single-market-economy.ec.europa.eu/sectors/mechanical-engineering/equipment-potentially-explosive-atmospheres-atex_en

(2) https://www.hse.gov.uk/fireandexplosion/atex.htm




Michal-Wozniakowski-Zehenter

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Michal Wozniakowski-Zehenter, Marketing Manager

Michal Wozniakowski-Zehenter is an experienced marketing and project management professional. He spent most of his career on projects with a strong focus on digital marketing and event management. He is a very active voice representing offshore and mining industries through social media channels. Michal writes mainly about offshore oil and gas, renewable energy, mining and tunnelling. Compiling and sharing the knowledge within industries is one of his goals.

Find here a selection of his articles.

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