01 Feb Design and Installation of Atex Zones

The design and installation of ATEX Zones must comply with the European ATEX Directive, a specific regulation aimed at guaranteeing the quality and safety of certain products and equipment that have to be used in environments where it is possible an explosion due to handling flammable substances.

The classification of the equipment suitable for working in the different zones is established according to criticality levels (this is known as ATEX zones), and the risk of explosion materializes when accidentally that explosive substance comes into contact with the air, existing the risk that, after accidental ignition, a deflagration may occur which could affect people and equipment present there.

The ATEX regulations affect both the work teams that are present in that risk zone, which have to be built with resistance criteria so as not to cause explosions, as well as the personal protection equipment and tools that workers use, since they have to be effective in preventing damage from a possible explosion.

What is the ATEX Directive?

The ATEX directive originates from the European Directive 94/9 CE, which regulates the requirements that electrical, mechanical and electronic devices, components and protective equipment must meet to ensure a level of resistance to explosions. These regulations came into force in July 2003 and a transitional period of three years was established so that equipment manufactured before that year could be adapted to the new requirements.

In April 2016, Directive 2014/34 / EU was approved, repealing the previous directive 94/9 CE. This regulation applies to all manufacturers of products, components or protection equipment that must be used in ATEX zones. These products would also include all electrical and mechanical equipment, as well as its components.

This directive is fully applicable in security systems for industrial buildings where the circumstances exist for an explosive atmosphere to occur, such as grain storage or storage of explosive powdery minerals.

Control devices are expressly included which, even if they are outside of this explosive environment, serve to guarantee the correct functioning of the devices and protective equipment that are.

Devices and protection systems for ATEX environments can only be marketed or distributed if they have the CE conformity marking. The CE marking implies that the appliance is built in accordance with the health and safety regulations of the European Union. The products must comply with the evaluation processes that are established and must also include a complete instruction manual that is understandable by users. As an example, we could cite the explosion-proof cameras that are used to monitor in these ATEX environments.

Having ATEX certified equipment guarantees that if a possible cause of an element that triggers an explosion (hot spot or electric arc) occurs inside it in a risk area, it is not possible for it to flourish outside the enclosure or device case. It must be taken into account that for an explosion to occur, three circumstances must coincide: existence of a combustible substance (gases, vapors, dust, mist), existence of an oxidizer (oxygen in the air) and the presence of an ignition source capable of causing the reaction between fuel and oxidizer.

Obviously, it is not possible to prevent the existence of fuel and oxidizer in protected areas, so the objective of risk protection focuses on the impossibility of propagation or existence of the ignition source.

The ATEX regulation tries to guarantee safety in activities where there is a risk of explosions, such as mining, the chemical or oil industry. Also in logistics and production centers where potentially explosive substances are present.

The manufacturer has to demonstrate that the behavior of these devices is adequate in areas with explosive risk. Depending on the level of danger and exposure to that risk, more or less strict requirements will be required to be able to assess their compliance.

The ATEX 137 standard is a European Directive that complements Directive 2014/34 in the field of protection of health and safety at work. The minimum requirements are established to preserve the safety of workers. Areas where there may be a risk of explosion must be identified and classified, and it must be marked so that everyone knows it.

A classification of personal protective equipment is also established that is associated with the level of risks that exist according to the different ATEX zones established by directive 2014/34.

ATEX zone classification

One of the most important points for the Design and Installation of ATEX Equipment is the classification of the ATEX zone, which will depend on two fundamental parameters. The first would be the type of substance that can cause that explosive atmosphere. There are four types: gas, steam, fog or dust.

The second would be the degree of presence of that explosive atmosphere: occasional, which only appears in specific circumstances; sporadic, when it appears in an unforeseeable way. The duration of the explosive atmosphere from detection to complete elimination would also be taken into account here.

Based on these parameters, an ATEX zone classification is established.

Zone 0

In this type of work area, the explosive atmosphere is permanent and lasts during all operations carried out in them. An example would be warehouses where flammable substances are deposited. The ATEX risk is continuous.

Zone 1

It is that work area in which there is a high probability that an ATEX atmosphere will appear when working under normal circumstances. When the explosive atmosphere appears, it is maintained for a short period of time. An example is found in workplaces where a flammable liquid is occasionally handled.

Zone 2

It would be that work area in which, under normal conditions, an explosive atmosphere will not occur. It would only occur in very specific circumstances and for a short period of time when some operations are carried out that may cause an unexpected leak.

Zone 20

In these work areas, the explosive atmosphere comes from dust clouds that are permanently present during the course of normal work. In addition, the explosive atmosphere would be prolonged in time.

Zone 21

The explosive atmosphere can occur occasionally and in the form of a cloud of dust, during the normal course of work.

Zone 22

Under normal conditions, explosive atmospheres in the form of a dust cloud are unlikely to form in the work area.

The objective of all these regulations is to ensure safety in work environments with risks of explosion. The design and installation of ATEX equipment has to comply with more complex technical requirements than those that are not prepared for this type of production center.

In addition to the European ATEX standard worldwide, the IECEx standard is applicable, which is an equivalent of the ATEX standard that is mandatory in Europe but promulgated by the International Electrotechnical Commission (IEC).

The main difference between the two is that the ATEX standard is applicable and mandatory for countries of the European Union, while the IECEx certification is accepted globally. Although it is common for any product to have both certifications since they regulate similar protections in specific risk areas. This is one of the most important points in the Design and Installation of ATEX Equipment.