When somebody asks for ATEX equipment, a step has usually been skipped. The acronym comes from the French ATmosphères EXplosibles and describes equipment designed not to become the ignition source of a mixture that can catch fire. But which equipment is the right one depends on the hazardous area classification of the place where it will work, and that classification is produced by the company with its health and safety professional, not by the supplier. This page explains what an explosive atmosphere is, how it is classified and why the order matters so much.
What is an explosive atmosphere?
It is a mixture of air with a combustible substance in the form of gas, vapour, mist or dust, in a proportion such that, if an ignition source appears, combustion propagates through the whole mixture. Put simply: it is not enough to have something flammable in the warehouse. It has to be dispersed in the air, in the right proportion, with something able to ignite it. That is why the same product can be harmless inside a closed drum and dangerous while being decanted. The practical consequence is that the risk is tied to the operation rather than to the goods: the same building can have sectors with no risk at all and one specific point, next to a filling nozzle or a mill, where the mixture does form. That is why it is studied by sector and by task, not by whole warehouse.
Where it forms: gases, vapours and dusts
The best known cases are liquids that give off vapour: solvents, alcohols, fuels, some industrial cleaning products. There the atmosphere forms around decanting, container filling or an uncontained spill. The less known case, and the one that most surprises people during surveys, is combustible dust. Flour, sugar, starch, milk powder, plastic resins, coal, wood and several metals produce dust that ignites when suspended in the right proportion. A dry food warehouse with a dosing area can have an explosive atmosphere problem without a single product labelled as flammable. And there is a second mechanism specific to dust: the layer accumulated on structures and light fittings, which does not explode on its own but is thrown into suspension by the blast of a first small event. That is why cleaning is part of risk control rather than a matter of tidiness.
What hazardous area classification is and who does it
Hazardous area classification is the study that determines in which parts of the installation an explosive atmosphere can form, with what likelihood and for how long, and it does so separately for gases and vapours on one side and for dusts on the other. The output is a drawing with delimited sectors and a report explaining the criteria. That study is produced by the company through a licensed health and safety professional, who knows the process, the real quantities, the existing ventilation and the operating procedures. It is not produced by the equipment supplier, who has neither that information nor the corresponding professional responsibility. In Argentina the general framework is Ley 19.587 on Occupational Health and Safety and its Decreto 351/79, and how it applies to your installation is defined by that professional and the relevant enforcement authority. That is why this page does not tell you which zone applies to you: it is not something that can be published in general terms.
What it means for equipment to be prepared for a given zone
It means the equipment is designed not to be the ignition source under the conditions of that zone. That translates into concrete engineering decisions: motors and electrical components that do not produce accessible arcs, enclosures that contain the event or keep the mixture out, surface temperatures kept within limits so that no hot part ignites settled dust, matching cabling and connectors, earthing and static electricity control, materials that do not spark on impact or friction, and a maintenance regime that preserves all of that across the life of the equipment. It is not a label stuck on at the end: it is a design category decided before manufacturing, and it arrives with its documentation. Whether what that documentation says matches what your installation needs is validated by your health and safety officer, not by the catalogue.
Why does classification come before equipment specification?
Because without classification there is no way to know which equipment is appropriate, and both possible errors are expensive. Over-specify and you pay for equipment prepared for conditions the installation does not have, plus more demanding maintenance and spares across its whole service life. Under-specify and the equipment cannot be used where it was needed, leaving the investment stranded. There is also a third outcome, the most interesting one and the most often overlooked: classification frequently changes with process measures. Improving ventilation, capturing dust at the point where it is generated, closing a decanting operation that is open today, containing a chronic spill or swapping one solvent for another reduces the classified sector or removes it. When that happens, the special equipment stops being necessary, and the money that was going into specification goes into fixing the cause.
What automation adds in a classified area, and when it does not
Inventory accuracy is measured by comparing records with physical stock. Results depend on receiving and dispatch records, location rules, training and controls; software or robots do not guarantee an accuracy percentage.
How the project is ordered in practice
The sequence that works is this. First the hazardous area classification study, with its signed drawing and report. Then the review of what can be changed through process, because it changes the scope of everything that follows. Only then the equipment specification, made against the zone drawing and not against a verbal description. After that, detailed engineering, manufacturing and installation: where imported equipment is involved, installation takes 3 to 4 months from the purchase order. The system is delivered with the documentation the permit process requires of the equipment, and that documentation is folded into the file your health and safety officer submits. STOKA does not license installations and does not certify how your warehouse is classified: it designs, imports, installs, integrates and supports. If you arrive with the classification already done, the conversation starts in the right place.
The zone drawing before the catalogue
ATEX is not a feature added to a machine: it is a design category that answers a hazardous area classification which has to exist first. The correct order is to study the risk, see what can be corrected through process, and only then specify. Reversing it leads to buying too much, buying too little, or buying something a ventilation improvement would have made unnecessary. If you already have the zone drawing, STOKA can specify equipment against it. If you do not have it, that is the first step, and it is not ours.
Frequently asked questions
A mixture of air with a combustible substance as gas, vapour, mist or dust, in a proportion such that, if an ignition source appears, combustion propagates through the whole mixture. Having something flammable in storage is not enough: it has to be dispersed in the air in the right proportion, with something able to ignite it.
The acronym comes from the French ATmosphères EXplosibles and denotes equipment designed not to be the ignition source in an explosive atmosphere: no accessible arcs, surface temperatures kept within limits, suitable enclosures, static electricity control and maintenance that preserves those conditions. It is a design category with its documentation, not a label.
The company, through a licensed health and safety professional who knows the process, the real quantities, the ventilation and the procedures. It is not done by the equipment supplier. In Argentina the general framework is Ley 19.587 and its Decreto 351/79, and how it applies is defined by that professional and the enforcement authority.
Yes. Combustible dust in suspension creates explosive atmospheres: flour, sugar, starch, milk powder, plastic resins, wood, coal and several metals. A dry food warehouse with a dosing area can carry the risk without a single product labelled as flammable. The dust layer accumulated on structures counts too.
No. First it is worth checking whether the classification can be reduced or removed through process: ventilation, dust capture at source, closing open decanting operations or containing spills. If that works, the special equipment is no longer needed. Only if the zone persists does it make sense to specify equipment prepared for it.