Many industrial facilities handle substances that, under certain conditions, can generate explosive atmospheres. These atmospheres are not exclusive to the chemical industry; they can be present in common activities such as handling grains, sugar, flour, wood, coal, paints, solvents, or cleaning processes with flammable vapors.

ATEX equipment exists precisely to reduce the risk of an ignition source (electrical, mechanical, or thermal) causing an explosion in these types of environments. The objective of this guide is to explain what ATEX equipment is, when it should be used, and how to select the appropriate equipment for the required application.

What is an explosive atmosphere?

An explosive atmosphere is a mixture of:

Flammable substances (gases, vapors, mists, or combustible dusts)
Air (oxygen)
In proportions such that, in the presence of an ignition source, combustion spreads rapidly.

For an explosion to occur, three elements must coincide, known as the explosion triangle:

Fuel
Oxygen
Ignition source

ATEX equipment is designed to prevent or control ignition sources, significantly reducing the risk of explosion.

What does ATEX mean?

ATEX comes from the French term ATmosphères EXplosibles and refers to the set of European directives and standards that regulate:

The design and manufacture of equipment intended to operate in explosive atmospheres
The safety of people working in these areas

Although it is a European regulation, ATEX is widely used as an international technical reference, even in countries where it is not legally required.

Types of Explosive Atmospheres

4.1 Gases, Vapors, and Mists

Includes flammable substances such as:

Natural Gas
LPG
Solvent Vapors
Fuel Vapors

4.2 Combustible Dusts

Includes solid materials present as fine particles, such as:

Flour
Sugar
Starch
Wood Dust
Coal Dust
Metal Dusts

A critical point is that a material that is not hazardous in its solid state can be highly explosive when suspended in the air.

ATEX Zone Classification

The zone classification indicates the probability and duration of the presence of an explosive atmosphere.

5.1 Zones for Gases and Vapors

Zone 0: Continuous or prolonged presence
Zone 1: Occasional presence during normal operation
Zone 2: Unlikely and short-duration presence

5.2 Zones for Combustible Dusts

Zone 20: Continuous or frequent presence
Zone 21: Occasional presence
Zone 22: Unlikely presence

In zones 0, 1, 20, and 21, the use of ATEX equipment is not optional; it is a technical and regulatory safety requirement.

What is ATEX equipment?

It is any equipment designed and certified to operate safely in areas with a risk of explosion. This includes:

Motors
Fans
Lighting
Sensors and instrumentation
Electrical panels
Valves and actuators

This equipment limits the generation of sparks, electrical arcs, hazardous surface temperatures, and mechanical failures.

ATEX Categories and Marking

ATEX equipment is classified according to:

Use group
Protection category
Type of atmosphere (gas or dust)
When should ATEX equipment be used?

ATEX equipment must be used when:

An ATEX zone classification exists
Combustible dusts are handled
There is a risk of dust accumulation on electrical equipment
Flammable vapors are handled in confined areas
The risk analysis indicates it

Standard equipment may operate for years, but that does not mean it is safe.

The quality of both the installation and the electrical power supplied to ATEX equipment is critical because problems such as:

Overvoltages
Phase imbalance
Harmonics
Improper start-ups

Can cause overheating that compromises the equipment’s ATEX certification, potentially leading to an accident. Therefore, proper electrical selection and preventive maintenance are essential.

Common Mistakes in ATEX Application

There are common mistakes when ATEX equipment is required in industry, and these are not necessarily related to poor equipment selection, but rather to a lack of understanding of the regulations. For an ATEX zone, it’s important to emphasize that not only must the equipment’s motor be certified, but also all its components, such as the casing, sensors, valves, and any other mechanical or electrical elements present in the zone.

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ATEX certification for equipment should be understood as a comprehensive prevention strategy that, along with ventilation, cleaning, ignition source control, and properly trained personnel, ensures the safety of equipment and people working in these hazardous areas, thus protecting their physical well-being.

Eng. Emmanuel Fernández Vortice Latam