ATEX & Explosion Safety Awareness Explosive Dust Atmospheres

ATEX & Explosion Safety Awareness Explosive Dust Atmospheres Dust! It’s everywhere… In households it is primarily tiny fibers launched into the air every time we sit on fabric-covered furniture; it’s tiny fibers coming from our clothes as we move around; it’s our own skin cells that we all shed at a rate of four kilograms … Read more

ATEX & Explosion Safety Awareness Explosive Dust Atmospheres Dust! It’s everywhere… In households it is primarily tiny fibers launched into the air every time we sit on fabric-covered furniture; it’s tiny fibers coming from our clothes as we move around; it’s our own skin cells that we all shed at a rate of four kilograms per person, per year. Typical dust is insufficient to pose a significant hazard in a home. Unless…

Imagine you’re working in your woodshop, using a belt sander to finish a large tabletop. You’re wearing eye protection, a respirator, and the air is so dense with dust you can hardly see the other wall…

Now imagine if that dust made its way to the pilot light on your furnace or boiler… or if the motor of the belt sander had brushes that produced a continuous stream of arcs while operating… Even in your own home, you now stand a good chance of becoming a safety statistic by not using a dust collection system.

Dusty Industries

Pharmacology industries use a great deal of extremely fine and chemically inert powder to create compressed tablets, pills, and capsules. The food processing industry uses substances like flour, powdered sugar, finely ground cinnamon (tree bark), and corn starch, all of which can be easily made airborne. The paper and lumber industry is just like our home workshop owner and can create an immense amount of fine sawdust and airborne particulates.

Depending on the materials, different products burn at different speeds. Industries that produce powdered milk, baked items from hundreds of thousands of tonnes of ground grains, and corn powder products face similar risks, but they are not the same. Corn powder ignites more easily than sawdust, for example, and sugar is a pure hydrocarbon, making it an extremely efficient fuel-burning both hot and quick.

Moist particles require more energy input to ignite since water has such a high specific heat capacity, thus resisting burning. On the other hand, small particles burn faster than large particles.

Why is Dust Vulnerable to Combustion?

Just as large animals have less surface area per volume than small animals, large particles expose less of their fuel to heat and oxygen than small ones. This is why a log can burn for hours and hours, but a sawdust particle can be consumed in less than a millisecond. Some materials even spontaneously ignite upon contact with a hot surface.

There is certainly less fuel available in a tiny speck of dust than a full log, but its surface area is immense compared to its fuel, so it “flashes” in an instant, totally spent. At that moment it creates a tiny fireball around it many times its own physical dimensions as its energy is released.

If there is a lot of similar material around it, dense enough that its brief, bright flare can connect with a dozen other particles, it touches off a cascade that can tear through the entire volume of dust in seconds. This is a deflagration.

The other type of atex explosion, the detonation usually occurs with volatiles (things that evaporate) that have a great deal of chemical potential energy, too, rather than merely the ability to combust. Detonations occur faster than the speed of sound (hypersonic) and do their damage through pressure waves. Deflagrations occur at sonic or subsonic speeds and do their damage with heat and flame.

Most Dust can Combust

There are always exceptions, say, for example, talcum powder. It is non-inflammable, non-explosive, and waterproof; however, by and large, we can safely assume that nearly all powders with a particle size smaller than half a millimeter (0.5 mm) will present a safety risk.

So-called “safe” dust is that which is not airborne, but it is only safe from atex explosion if it remains in that state. It can easily become explosive with just the wrong circumstances occurring. The slightest eddy or breeze, say by opening a door, could cause fine dust to become airborne, sufficiently concentrated, and surrounded with the essential oxygen it needs to burn.

On the other hand, hot sparks from a grinding operation could set a dust layer alight. An arc or gas welding operation overhead could be the trigger for a fire in a dust layer, too. This is why Housekeeping is essential for safety. We should never let dust accumulate.

Silos are Vulnerable to Atex Explosion

Silos often circulate air to keep grain dry. Corn stored for a year waiting for market prices to rise is just as good for food production, animal feed, or whatever other need arises because it is hard, dry, and ready to process. That air circulation also helps to prevent insect infestation, as well as removing dust below the LEL, or Lower Explosion Limit, rendering it safe.

The problem arises when the moisture content gets too low, the heating gets too high, and the dust levels rise to dangerous levels. At that point, you’re looking at a potentially explosive situation. On average, in the United States, there are 11 silo explosions per year, two deaths, and 13 injuries.

Description

This corn elevator (a series of buckets conveying grain to the top of the silo), despite its steel construction, was ripped open in the resultant blast. Conditions evolved where heat, dryness, and possibly something as simple as a static discharge, set off an explosion in the relatively small space. If it had propagated further into the silo the entire structure could have been demolished.

Assessing the Risk for Atex Explosion

The environment must be evaluated. Are the particles 0.5 mm or smaller? How much dust do the individual machines and processes accumulate between cleanings? What is the total amount of dust in the facility? Does the dust ever exist in sufficient concentrations to ignite?

If vision is obscured over just a meter or so of distance, in all likelihood the density is sufficiently risky to take measures. Increased ventilation is one possibility, but how that is done can amplify the risk (such as opening many doors) or reduce it (vacuum collections systems at the point of generation). The latter idea of altering the process such that it never reaches a dangerous level is better.

After all, if a high level of dust occurs periodically, there is a significant likelihood that a layer of dust will remain afterward. It only takes a layer 0.1 mm thick to present a risk. Such a layer, particularly if it is dry, can be drawn into a vortex of air and recreate the hazard even when that process is no longer running, and when no one is prepared for it.

People may know that cigarette smoking is forbidden during the dust-generating process and yet smoke freely at other times. If someone opens a door and a stiff breeze loft a large amount of dust into the air, will the smokers have the wits to immediately extinguish their cigarettes before the dust cloud reaches them?

Once again: this is why Housekeeping is essential for safety. The need for thorough cleaning after each dust-generating event might inspire changing the process to eliminate dust as much as possible to save downtime for cleaning. Also remember to only use atex certified equipment in the zones, such as our ATEX Keyboard.

The Zones

There are three zones of concern with explosive dusty atmospheres. A facility may be rated largely as Zone 22, which is very unlikely to ever experience a condition where an explosive atmosphere exists. Offices come to mind, but it could as easily be a portion of the facility sufficiently far from the generation point as to be essentially immune.

Description

Next is Zone 21 where some risk can exist, usually on an occasional basis. Generally speaking, this can be the area immediately surrounding the actual generation point. It could also be a point separated from the risk zone but where a blower or vacuum system has the potential to leak dust away from the actual process.

The last is Zone 20 where there is a near-continuous possibility of dust density existing capable of posing a hazard. Sanding operations in wood mills and processing plants are a prime example, but silos of all types pose some risk, such as grain, starch, sugar, or filler agents for food or pharmaceutical products.

The Takeaway

Some processes are inherently dusty. Mining granite, marble, or chalk can be done with impunity. But coal dust has resulted in the deaths of thousands worldwide. In comparison, a methane explosion is almost tame, though such a thing can trigger a coal-dust explosion, if they are found together.

dust explosion
Description

Similarly, any commercial process, involving almost any organic powder, can be hazardous. Sugar, one of the most common compounds in food processing is a hydrocarbon with its own oxidizer built-in as C12H22O11, or as we like to call it, a carbohydrate.

Powders are essential to most of our manufacturing processes. We must control the five Dust Atex Explosion factors.

These are fuel, ignition (sparks, arcs, hot surfaces), oxygen, confined space, and dispersion (fuel density); these are paramount for safety. Refining your process. So that it does not provide fuel is probably the easiest and most economical route. Since most dust amounts to wasted product. Let’s reduce the risk!

ATEX & Explosion Safety Awareness

There are two directives that address explosion safety awareness and prevention in the European Union. The first, known as ATEX 137, speaks to occupational safety, as it applies to Employers, Manufacturers, and Employees. The second, ATEX 95, addresses those requirements in the EU (and outside countries that wish to export to the EU, e.g. India) … Read more

There are two directives that address explosion safety awareness and prevention in the European Union. The first, known as ATEX 137, speaks to occupational safety, as it applies to Employers, Manufacturers, and Employees.

The second, ATEX 95, addresses those requirements in the EU (and outside countries that wish to export to the EU, e.g. India) for the manufacturing of safe, explosion-proof equipment, devices, and materials. These manifest as a series of directives that all must follow. Anywhere you go in the EU, you will find consistent rules regarding the treatment of explosion hazards.

Directive ATEX 137 (officially “Directive 1999/92 / EC”)

In the Netherlands, for example, ATEX 137 is anchored in the Arbo/Arbowet (Working Condition Act). This requires that employees and the employer agree on what constitutes acceptable working conditions. This agreement is then enforced by a safety officer employed for that purpose. In small companies (25 employees or less) this role can be fulfilled by a company director.

Employer Duties under ATEX 137

An employer is responsible for creating a safe working environment and the implementation of all measures to guarantee the safety and health of the employees. This includes for their own working staff, as well as invitees (legally: any person implicitly or explicitly invited onto another’s property for mutual gain, such as a depositor entering a bank or a customer entering a restaurant), or any third parties such as repair persons, or drivers that come to load or unload).

The employer is responsible for informing and giving instructions to employees, invitees, and third parties. This can be done by signage (such as: “Visitors must wear hard hats” and “Stay in designated areas”), by direct instruction, or by educational means, such as provisioning and requiring the completion of training courses.

The Explosion Safety Document

Initially, the employer maps out all known risks, such as:

  • The probability of an explosive atmosphere occurring, and its persistence;
  • The likelihood that ignition sources are present;
  • The equipment, installation, substances, and processes used;
  • The magnitude of the consequences of failures.

These are recorded in the Explosion Safety Document, along with the measures to be taken to mitigate these risks. This document is mandatory for every organization where there is a risk of explosion.

Finally, the employer must keep the information up-to-date. If new equipment is added, if machinery is changed, or upgraded, or production processes are changed, the material must be reviewed and made to conform to safety requirements.

This requires the creation of procedures that will mitigate those potentials and promote safe working practices. Employees may even be tasked to assist in the creation of the rules and methodologies, after which they are codified and everyone learns them.

The Basic Principles

  • Arrange the workplace so that work can be done safely;
  • Guarantee appropriate supervision; and,
  • Provide appropriate training to employees.

Additionally, with particular reference to explosion hazards, this requires an employer to perform Risk Assessment to:

  • Prevent the creation of explosive atmospheres; and,
  • where this is not possible, avoid the possibility of ignition; and,
  • thoroughly understand the equipment, substances, and processes used; and,
  • in the event of ignition, mitigate the harmful effects of an explosion.

Employee Duties

Preventing explosion hazards not a one-way street, however. Employees are required to work in a safe manner to protect themselves and others from harm. This requires awareness of rules and procedures, zone regulations within buildings, as well as emergency escape routes within the areas where they regularly work.

Additional obligations include working in such a way as to prevent an explosive atmosphere from developing. This is partly achieved by employing the Clean Household strategy. This means keeping materials from accumulating to the point where they could become airborne and thus become an explosion hazard.

If there are shrouds to prevent dust-infusion into the air, static arrestors to prevent sparks, or techniques to prevent an explosive atmosphere from developing by the unnecessary resuspension of dust, these must be used or followed.

Similarly, with potentially explosive vapours, proper venting must be functional and operating during processes that generate it; non-certified equipment must never enter the area; procedures must be followed, and protective equipment must be used.

Directive ATEX 95 (officially “European Directive 94/9 / EC”)

Explosion Safety Awarenes

This, of course, is the compendium of European product directives for the manufacture of explosion-proof material. The basis lies within ATEX 95, the machine directives, and the rules regarding CE marking.

The directive covers both electrical and mechanical equipment.  All such equipment must be certified by an official inspection body (a ‘notified body’), such as, for example, TÜV Rheinland.

 

Manufacturers Duties

This group is responsible for bringing devices and equipment to market, which meets the safety requirements. In electrical equipment, for example, lighting fixtures for explosive atmospheres must be sealed so that sparking connections, exploding bulbs, or other components cannot move flame, spark, or heat outside of the fixture.

 

Explosion Safety Awarenes

Junction boxes need not be hermetically sealed if they are intrinsically designed to have no spark generation. This junction is all direct connections with no switches or contactors, and thus noted as EX-e, for enhanced safety.

 

Switches designed with very low voltages are not capable of creating an energetic enough spark or sufficient heat to ignite dust or gas, and are therefore listed at EX-i, for intrinsically safe.

Mechanical devices must also be incapable of generating heat or sparks during failure (overworked bearings or gross mechanical failure) in order to meet certification.

Zones & Categories

Explosion Safety Awarenes

Understanding zoning is very important. Most everything in daily life is Zone 2 or Zone 22, where there is little chance of (respectively) a vapour or dust-based explosive atmosphere evolving. In this environment electrical equipment can be category 3, which is safe in normal, everyday operation

Zone 1 and Zone 21 are places where such an explosive atmosphere could exist on an occasional basis. It is predictably created during specified operations. In this instance, Category 2 is called for, which is safe in normal circumstances, and safe in instances where potential faults are known, understood, and taken into account.

Zone 0 and Zone 20 are places where explosive atmospheres virtually always exist. Grain & powdered sugar product processing, petroleum product cracking, suspended sawdust in lumber mills, methane gas in landfills or sewage treatment plants, or spray painting operations, are all excellent examples. These will require Category 1 equipment, which is safe and reliable in circumstances where even two simultaneous faults occur, independently of each other.

The Takeaway

ATEX 137 & ATEX 95—The Relationship

Employee, employer, and manufacturer responsibilities (ATEX 137) are intimately related to the sort of equipment used (ATEX 95) in a zone of known risk. Normally safe Category 3 equipment is not safe in Zones 1/21 or Zones 0/20. Similarly, Category 2 equipment is not safe in Zones 0/20.

You can certainly use Category 1 equipment in any Zone, but economics dictates that you use less expensive equipment where such high levels of safety are not required.

Ultimately, ATEX 137 & ATEX 95 regulations are designed to protect you, whether you’re the employer, employee, visitor, third party. Take advantage of the work already done to diminish your risk.

The Basics of Explosions in Industrial Sites

Explosions are sudden, localised, overpressure events.  They result from a rapid increase in volume and energy upon ignition of a fuel with available oxygen, and the consequent release of heat, kinetic energy, and high-pressure gases. Normal explosions erupt at a speed of up to 340 metres/1,120 feet per second, the speed of sound in dry … Read more

Explosions are sudden, localised, overpressure events.  They result from a rapid increase in volume and energy upon ignition of a fuel with available oxygen, and the consequent release of heat, kinetic energy, and high-pressure gases.

Normal explosions erupt at a speed of up to 340 metres/1,120 feet per second, the speed of sound in dry air.  This is what occurs in ordinary industrial or commercial atmospheric explosions and are the focus of ATEX legislation.

Explosions that occur faster than the speed of sound are referred to as detonations, and require manufactured or engineered tools, chemicals, and materials to occur.  The energy of these events travels as shock waves through the medium, with less displacement of the medium itself.

 These occur more commonly in mining operations because of the use of specific materials. This discussion is confined to ordinary explosions such as the ignition of atmospheric dust, gas, or vapour.

Risks per Industry

Some risks are obvious even to a casual observer, while some are invisible without some familiarity with the operation or processes involved. Certain industries require equipment suited for ATEX Zones. For example our ATEX Camera, which is suited for environments with a risk of gas explosions.  Let’s consider some examples.

Obvious

  • Chemical Industry
    • Many chemical combinations are inherently explosive
    • Powders, once airborne, also present a hazard
  • Power Generation
    • Coal dust is fuel
    • Natural Gas is a fuel
  • Woodworking Industry
    • Fine sawdust is an excellent airborne fuel
  • Biomass Plants
    • Methane gas
    • Wood dust during pelletising process
  • Metal shops
    • Many metals (e.g. Aluminium or aluminium mixtures) will oxidise rapidly and explosively

Hidden

  • Food Industry
    • Powdered sugar is a pure hydrocarbon
    • Milled grains burn easily and energetically
  • Waste Treatment Plants
    • Fermented gases (e.g. methane) burn readily
    • Chlorine gas combines with ammonia to be highly explosive
  • Pharmaceuticals
    • Cellulose and lactose are used as pill-fillers and are explosive as airborne dust/particulate
    • Various alcohols are used for blending and formulations
  • Landfill Sites
    • Evolved gases (e.g. methane, hydrogen sulphide)
  • Paint Shops
    • Solvents as mist can form explosive atmospheres
    • Paints (metallic or organic) can be fuel

Gas Dangers

Gas explosions can cause immense damage because vapours or gases can insinuate themselves into cracks and crevices, move between rooms, and are often invisible.  Until they meet a source of ignition, people may not even be aware of their presence. 

Some are odourless, too, such as methane, which is why we add gases like hydrogen sulphide or methyl mercaptan (aka methanethiol) to alert people to leaks of natural gas, or before that, of coal gas.  Those flammable additives are easily detected by the human nose, even in miniscule quantities.

Gases ignite very easily, say, by just a static electric spark.  Something as ordinary as the connection arc of a light switch can set off a gas explosion.  Someone lighting a match or turning on a gas range with an auto igniter for the gas could be the cause.  A home explosion from a natural gas leak could be triggered by an old-fashioned house-phone ringing—their solenoids spark when they rapidly make and break the electrical connections to ring the physical bells inside.

Dust Dangers

Generally speaking, dust explosions are harder to ignite than gas.  The fuel first has to be airborne, and then something hot enough to ignite a particle must exist.  After it is started, it expands by a cascade effect where one burning particle supplies sufficient energy to ignite its neighbour.

Different size particles can represent different levels of threat, just as density per cubic volume can alter an explosion’s characteristics.  Coarse sawdust is less dangerous than very fine sawdust in the same density/volume.  Very fine sawdust has a massive surface area compared to its available energy.  It can be consumed quite quickly releasing all of its energy at once.  Large particles have more surface area and less fuel, so burn more slowly, and take more energy to reach a critical point.

Propagation

A dusty work environment with outside ventilation might be safe, but if several individual units share common ventilation, fire can propagate through that system from one unit to the next.  This is why such ventilation connections require shutters that slam shut when there is an extreme pressure change on one side, preventing flames from passing to another area.  The explosion can only vent outside of the building, not within different units.

Ventilation Shutter

Other Dusty Dangers

Dust accumulates around equipment such as coal conveyors, for example, or chutes and movement systems for flour, sugar, and other dusty products.  These need regular maintenance and clean up so powders and dusts never reach dangerous levels.  It may be benign just lying there, but a wind gust can turn it into an instant threat.

Explosion Elements

Oxygen is 20% of our atmosphere and thus hard to eliminate, so generally we work to limit the availability of fuel and the ignition source.

Ignition causes could be a spark, open flame, or a heat source, like an electrical radiant heater. Fuel can be dust, gas, or vapour.  If any one element of an explosion is absent, the explosion won’t occur.

Explosive Properties of Fuels

Fuels only react in certain ratios.  For example, hydrogen will react (with atmosphere) at concentrations over 5%, but less than 95%.  Some fuels have much more constrained limits.  We call these limits the UEL and LEL, or Upper and Lower Explosion Limits, and they are expressed as percentages. 

If you exceed the UEL, or fall short of the LEL, explosions cannot occur.  Keep fuels outside of the limits and you are safe.  Similarly, if you keep the temperature outside of the combustion range of the fuels, that is safe, too.

Injuries from Explosions

Injuries are not always apparent.  Bleeding and physical trauma such as shrapnel are obvious.  Symptoms such as deafness, breathing difficulty, shock, concussive, or deep tissue injuries may not show physical signs.  All explosion victims are considered seriously injured until proven otherwise.

Serious burns can result from the extreme radiance of an explosion, too.  Outward signs may not manifest for many minutes after exposure, but the pain is real.

The Takeaway

It is difficult to control the presence of oxygen.  You must either control the temperature, keeping it below the point of combustion of the materials you are work with, or control the sources of ignition.

When fuel of any sort accumulates, it must be removed, physically in the case of dust and powder, or ventilated, in the case of gas or vapours.  Don’t become a matter of historical record…

Be aware; be safe; keep it clean; and, most importantly, do your regular maintenance!

The Imperial Sugar Refinery dust explosion was the largest in U.S. history.  It resulted in 14 deaths, dozens of injuries, and the complete and utter destruction of the more than one hundred year old facility. 

What Is ATEX Certification? In-Depth Explanation

What is ATEX? ATEX stands for ATmosphère EXplosibles (from the French for Explosive Atmospheres).  Formerly it combined two European Union (E.U.) Directives for defining environments where an atmospheric explosion hazard existed. There were a confusingly large number of variants describing the two main directives for ATEX.  With 27 countries in the E.U., there are a … Read more

What is ATEX?

ATEX stands for ATmosphère EXplosibles (from the French for Explosive Atmospheres).  Formerly it combined two European Union (E.U.) Directives for defining environments where an atmospheric explosion hazard existed.

There were a confusingly large number of variants describing the two main directives for ATEX.  With 27 countries in the E.U., there are a lot of opinions about what comprised proper nomenclature.

The older forms included Product Directive 94/9/EC, for equipment manufactured before 2016, which was also known as ATEX 95, ATEX 100a, or the ATEX Equipment Directive.  

The second aspect, the protective feature for people and property was known as Operating Directive 1999/92/EC, or Directive 99/92/EC, ATEX 137, ATEX 118a, or the ATEX Workplace Directive.

The variations, subtle and gross, were too disparate and confusing.  In February 2014, it was all harmonised by the European Parliament and the Council of the European Union under Directives for Equipment 2014/34/EU (aka ATEX 114) and for Health & Safety under ATEX 153

Whatever name it arrived under, it required that any device, electrical or mechanical, shall not provide a source of ignition in an explosive atmosphere.  They further specified that:

It is the duty of Member States to protect, on their territory, the health and safety of persons, especially workers, and, where appropriate, domestic animals and property, especially against the hazards resulting from the use of equipment and systems providing protection against potentially explosive atmospheres.

Ultimately this integration allows the free movement of ATEX goods anywhere in the E.U.—knowing that the same standards are upheld uniformly, everywhere—if the item bears the Ex symbol and has a certification.

What is ATEX Certification?

ATEX Approval Explained

ATEX Certification and ATEX Approval are precisely the same things, simply using different words.  To eliminate confusion, pick your favourite and stick with it. 

In the E.U., ATEX Approval is required for equipment that is to be used in potentially explosive atmospheres.  Generally speaking, these hazardous areas are found in the oil & gas, pharmacy, and woodworking industries, but can occur virtually anywhere, when the processes and/or circumstances allow.

The basic principle of the certification is that any equipment used in potentially explosive atmospheres must not form a source of ignition, or pose a Health & Safety threat to workers, employees, or property.  Such equipment must meet design specifications comparable to those set out in Directives ATEX 114 and ATEX 153.

ATEX Approval and ATEX Rated Products

ATEX Approval means that these products are suited to be used in explosive atmospheres, sometimes known as EX Zones.  Products that are safe to be used in EX Zones are sometimes also referred to as ATEX approved or ATEX rated. 

ATEX Types of Explosive Atmospheres 

Simply put, ATEX Approval states that atmospheric explosion dangers, threats to life and health, and property damage, must be mitigated and/or minimised for workers, owners, and members of the general public.

Common sources of ignition in electrical equipment are sparks from making or breaking a circuit (e.g. a light switch), or the ordinary operation of a standard electric motor that uses brushes.  Often, for example, if you look inside of the ventilation grate of a conventional electric drill when it is operating, you can see the fountain of sparks as the brushes continuously make and break contact to drive the motor, allowing it to turn.  In an ATEX zone, these sparks could cause an explosion.

ATEX is further subcategorised into two discrete environments, two types of hazardous material, and three levels of risk.  Let’s look at them now:

Environments

The two environments are above ground (typical), and below ground (mining).  Both environments are regulated, but the latter category is much more stringently regulated due to the significantly higher level of risk for injury and damage beneath the Earth’s surface. 

All explosions can cause both damage and fatalities.  In a confined space, however, the severe overpressure of an explosion is concentrated, propagating much further because of the limited expansion room.

Materials

There are two vastly different classes of materials to consider:

  • Flammable Gases, Mists, and Vapours
  • Combustible Dusts 

Flammable Gases, Mists, and Vapours exist in such industries as petrochemical processing, automotive painting, manufacturing pressurised propellants (industrial or household sprays), welding, and often, for home heating (e.g. Natural Gas).

Combustible Dusts occur in processing environments, such as lumber mills, food refining, grain storage, and coal mining.  Referring to organics, it is said that anything which did not originate in “rock” can provide fuel for a dust explosion.

In point of fact, rapid immolation of dust is responsible for most of the spectacular explosions that you see in films.  It provides a large visual effect (fireball rising), extinguishes quickly, and can be well-controlled in the proper circumstances. 

In an enclosed structure, however, the flames can race quickly from one end of the building to the opposite end and from top to bottom, in just moments.  Such was the case with the Imperial Sugar dust explosion, which generated such a huge overpressure explosion that it cost several lives and completely destroyed the sugar packaging plant.

Imperial Sugar Dust Explosion

Levels

Constant defines near continuous existence of airborne flammables, with only rare or occasional exceptions.  Frequent means regular occurrences, such as part of a process, where some event permits its existence for some period of time.  Rare identifies normal, everyday circumstances, where exceptional circumstances may arise.

In 1878, it only took a single spark to blow the solid concrete roof off of Washburn Flour Mill, sending remnants hundreds of feet in the air.  That accident changed milling forever in North America.  It destroyed the entire building, killed all 14 workers, knocked down two adjacent mills killed more workers there, and blocks of concrete and limestone rained down as far as eight blocks away from the site.  We learned from these events.

Our own ATEX Certified Explosion Proof Equipment are good examples of products that come with an ATEX certificate. It may therefore be used safely in specified hazardous areas.

Washburn Flour Mill

What are the applicable ATEX directives?

As noted earlier, there were a number of names by which these variations were known, but that has all been consolidated under Directives for Equipment 2014/34/EU (aka ATEX 114) and for Health & Safety under ATEX 153.  This creates consistency between all products sold (or imported into the E.U.) for use in potentially explosive atmospheres, anywhere in the E.U.

ATEX Certification Process

How to get ATEX Certification

ATEX certification requires product design to the standards as set out in the ATEX documents.  Your engineers will likely perform their own testing, but eventually it will need to be investigated by designated engineers at an approved testing facility so that an official certificate can be issued.

Low level testing for conventional use can often be done on-premises by qualified engineers, and the CE marking can be obtained.  More complex testing is required where threats are immediate, such as cyclic repeating of events subject to potentially explosive atmosphere risks.

An example might be a grain farmer using a conveyor or air-driven system to lift grain to the top of a silo.  Since it is an inherently dusty task, sparks, whether from static electricity or electrical motors, have to be eliminated.  In the confines of a concrete or steel silo, damage and life loss could be inevitable if things were to go awry.

Who provides ATEX Certification?

There are many familiar names providing certification.  Intertek is familiar in Europe, as the amalgamation of a 19th century British marine surveying business, a Montreal Laboratory, and Thomas Edison’s Testing Lab.

Similarly the CSA, or Canadian Standards Association, was founded over a century ago to provide engineering standards in Canada.  CSA is now a world renowned, non-governmental, independent group of engineers, and is a Notified Body for ATEX activities. 

The British Scientific Instrument Research Association (BSIRA), later known just as SIRA, was founded at the same time, and was another Notified Body for ATEX.  SIRA amalgamated with CSA in 2009 and still provides SIRA Certification Services (SCS) for ATEX.

The Deutscher Kraftfahrzeug-Ueberwachungsverein, (English: German Motor Vehicle Monitoring Association), or DEKRA is a Certifying Body (CB), too.  Indeed, even the U.S. Underwriters Lab (UL) is an ATEX Notified Body.  Clearly there is no shortage of expertise in this area from many respected testing organisations.

ATEX zone 2/22 certification

Zone “2” and Zone “22” indicate non-likely presence of explosive atmospheres.  The two (2) rating indicates the lowest ordinary possibility of flammable gas.  The twenty-two (22) rating indicates the lowest ordinary possibility of flammable dust.  The Ordinary Location certification requires nothing more than the CE mark as a self-declaration representing that the equipment conforms to expectations for the product type.   

ATEX Zone Logo

ATEX zone 1/21 certification

Zone “1” and Zone “21” indicate the occasional presence of explosive atmospheres due to a process.  Similar to the foregoing, the one (1) rating indicates the presence of flammable gas.  The twenty-one (21) rating indicates the presence of flammable dust.

ATEX zone 0/20 certification

Zone “0” and Zone “20” indicates the virtually continuous presence of an explosive atmosphere.  The zero (0) rating indicates the presence of flammable gas.  The twenty (20) rating indicates the presence of flammable dust.

ATEX Certification Requirements

Equipment and devices must be tested and certified to be safe in an explosive atmosphere consistent with their likely use.  A household air-conditioner, for example, needs only a CE certificate stating it meets the engineering requirements/standards for an a/c in the EU.

Something designated as safe in a dusty environment needs more significant proof and testing.  There are many organisations that provide such training, but there are just as many already set up to provide certification for your existing and new products on a much faster timetable.

ATEX Certification Cost

The prices for ATEX Certification depend on the individual products and the complexity of the testing.  Each item is going to be different.  Generally speaking, the simpler the device the lower the cost, and conversely the more complexity, the more extensive the testing must be.  This directly affects cost.

Indeed, zone two objects and devices will be less expensive than Class 0 devices or objects to certify.  Mining and high-risk explosive atmosphere testing are more intensive than making sure a vacuum-cleaner bag doesn’t explode, fill the air with dust, and then ignite it.  Something used a kilometre or two underground has to be failsafe – there are no second chances there.

ATEX Certifications Codes

Example of a typical ATEX Marking

ATEX codes are alphanumeric strings consisting of a five-part prefix and a five part suffix.  These codes represent harmonised standards so information equipment plates are consistent and readable anywhere in the E.U.  Some manufacturers take an extra step and add a second suffix because they have certified the device for both GAS and DUST environments so as to indicate compatibility with multiple dangerous environments.

Prefix

The first code identifies it as CE compliant followed by a four-digit number identifying the Notified Body.  Next you’ll see the EX hexagon, indicating that it has “explosive atmosphere” status.  Following that is the Equipment Group number with “I” for mines and “II” for everything else.

Next you’ll see a code representing the Equipment group.  M1 and M2 indicate mining equipment, and plain 1, 2, and 3 cover all the remaining possibilities outside of mining.

The last figure with be the environmental indicator—either G or D—to indicate whether it is for Gas or Dust.

Suffix

The suffix provides more detail about the protection level and how it is protected from explosion.  It also elucidates what those hazards are.

It always starts with Ex to indicate protection against explosion.  You’ll next see d, e, i(a,b,c), m(a,b,c), n(A,R,C), o, p(x,y,z,*), q, t(a,b,c), or pairs to show multiple qualifications, like eo, or de.

The “d” means flameproof; “e” refers to low risk of arcs, sparks, or hot surfaces;  “i” is safe for Zone 0 or 20 because it uses very low energy, minimal low energy sparks, and no hot surfaces; “m” refers to isolating incendiary parts from the atmosphere (oxygen source); “n” refers to non-sparking and is confined to Zone 2 where explosive atmospheres are rare to non-existent; “o” refers to oil-immersion; “p” refers to pressurised environments; “q” refers to powder-filled environments; “t” refers to dust tight equipment.

Next is I, II, or III, for (respectively) mining-only, gas, or dust.  II and III can be further appended with A, B, or C to provide additional information where A is more dangerous than C.

Next is line is the Temperature range for gases as T1-T6, indicating the highest temperature the equipment will reach, indicating how far from the combustion point of a given gas it will be, thus its relative safety.

For Dust, the letter T is followed by the maximum likely surface temperature in degrees Celsius.  T100ºC, the boiling point of water, could be fairly common, and T230ºC would be just below the ignition-point of dry paper.

Finally, the last figure in the suffix is the Protection Level afforded by the equipment.  Ma and Mb are strictly for mining applications, whereas you’ll see Da, Db, Dc, or Ga, Gb, Gc, for Dust and Gas, respectively.

ATEX Certification Mechanical Equipment

Mechanical equipment, also referred to as non-electrical equipment may also need to be ATEX Certified.  A good example is the rotor blades of a drone.  These blades generate static electricity when they are spinning.  Moving mechanical parts such as spinning rotor blades could form a source of ignition.

Consider the implications of flying a drone over a petroleum cracking plant.  In flight, the drone acquires a high static charge, which is relatively safe while it is airborne, but if it crashes or touches an object so that it discharges that static, that arc could set off a string of deleterious events.

ATEX Certification Courses

Courses for Certification abound, and we don’t look to promote any particular organisations.  Select a good one (see their reviews from their students) that is relatively close by and which covers the topics you need or desire.

One of your primary tasks is to identify hazardous areas, and to learn the basic principles.  You’ll need to understand the legal codes and requirements as well as the various types of equipment and test apparatus, and proper use thereof for assessments.

What you’ll be training for will vary but will probably include how to prepare ATEX EC Examination Certificates to provide the results of testing, how to make an Ignition Hazard Assessment (IHA), and how to apply the standards to reduce ignition sources.  You’ll also need to prepare Declarations of Conformity (DoC).  There is no escaping the paperwork!

ATEX Certification in Various Countries

Is ATEX certification applicable in North-America?

This simple answer is no, though we are seeing more ATEX-certified products, such as vacuum cleaners, being imported with that certification.  North America relies on NFPA (National Fire Protection Association), OSHA (Occupation Safety Health Association), the CSA, and the NEC (National Electric Code) for its standards. 

ATEX Certification US equivalent

The ATEX Ex rating does not carry official weight, and approvals must come from a Nationally Recognized Testing Laboratory (NRTL), which still includes reliable names like CSA, Intertek, TUV, and UL, among several others.

ATEX vs. IECEX

 ATEX is acceptable anywhere in the EU for equipment to be used in potentially explosive atmospheres.  IECEx, on the other hand, is internationally (globally) recognised.  The important part to remember which differentiates them is that ATEX is driven by regulation and law, whereas IECEX is driven by harmonised standards.  Your choice depends on where your sales will take place.  If they are likely to be both within and outside of the E.U., it makes sense to get both certifications.

ATEX Certification UK

Brexit, for better or worse, is fait accompli.  As a result, ATEX is a thing of the past in the U.K.  Despite that, standards will remain the same, since there are no current plans to modify them.  The name will change to UKCA, with this new symbol.  Beneath the symbol itself will be the 4-digit code which identifies the certifying authority.

The New UKCA

ATEX India

Electrical Consultants Association (ELCA) of India and the CSA are cooperating to provide ATEX certification for Indian Exporters selling products in the E.U.  The certifying body will be the IECEx for the Indian Laboratory, and that will provide an associate office in Mumbai for CSA ATEX certifications in India for their exporters.

Indian manufacturers do not use ATEX, relying instead on IECEx certification, but the E.U. New Legislative Framework, specifies ATEX Directive 2014/34/EU (aka ATEX 114) and ATEX 153 for India’s products exported to the E.U. for use in potentially Explosive Atmospheres. 

This will allow them to meet the EHSRs, or Essential Health and Safety Requirements, for equipment designed to work within specified potentially explosive atmospheres.  It also addresses the design of protective equipment (explosion arrestors) for those same potentially explosive atmospheres.

Directive 2014/34/EU (aka ATEX 114) and ATEX 153 provide specifications for both electrical and non-electrical equipment (such as rotors and propellors on aircraft and drones) that can create static electrical charges and discharges, when devices are intended for use in potentially explosive dust or gaseous atmosphere.

Like other jurisdictions, it also specifies that manufacturers, their authorised representatives, importers, and their distributors, are responsible to ensure that their items meet EHSR requirements before being exported to the E.U.