Within the ATEX directives of the European Union on primary, secondary and tertiary explosion protection, ATEX Zone 0 occupies a special position. This zone designates an area in which the presence of an explosive atmosphere is likely to be present continuously or for long periods of time. It therefore represents the highest level of explosion hazard and requires special safety precautions and corresponding certifications. ATEX Zone 0 is relevant for areas with potentially explosive atmospheres, as it forms the basis for preventing accidents and ensuring the safety of employees and systems.
ATEX directives
The ATEX Directive regulates explosion protection (explosion protection) in Europe and is enshrined in Directives 2014/34/EU and 99/92/EC. Industrial processes that often involve flammable substances, including dusts, require effective explosion protection, whether due to process-related releases or unforeseen faults. These directives specify the requirements that equipment must meet in order to be considered explosion-proof and define permissible working areas in explosive atmospheres, known as Ex areas.
Manufacturers of Ex devices must label them uniformly and specify the permitted area of application by means of a device category. Users, on the other hand, must divide their potentially explosive areas into explosion protection zones according to the type of hazard (dust or gas) and the presence of flammable media.
What are ATEX zones?
The ATEX zones (ATEX: an abbreviation of the French term Atmosphères Explosibles) are special areas in industrial plants and construction sites where the safety of personnel and equipment has top priority. They are created by precise measures to prevent potential hazards and are identified by the ATEX marking. ATEX stands for “potentially explosive atmosphere” and occurs when flammable substances are present that pose a high risk of explosion. An explosion can be triggered by six simultaneously occurring conditions, including the presence of oxygen, fuel and an ignition source.
The ATEX zones are divided into different categories depending on the level of risk and requirements. It is particularly important that the use of devices and equipment in these zones is subject to strict safety regulations in accordance with the ATEX directives, which regulate protection against explosions.
ATEX zones and classification
There are three main groups of ATEX zones, which are classified according to the type of potential hazard and the probability of the occurrence of explosive atmospheres. These groups can be described as follows:
- ATEX zone 0: In this zone, there is a permanent or prolonged risk of an explosive atmosphere forming. This is typically the case in areas where flammable substances such as gases, vapors or mists are continuously or regularly present in the air.
- ATEX zone 1: This zone includes areas in which the risk of an explosive atmosphere exists, but only occurs occasionally. This means that flammable substances are not normally permanently present in the air, but can be released under certain conditions, such as in the event of leaks or technical faults.
- ATEX zone 2: This zone describes areas in which the risk of an explosive atmosphere rarely occurs and, if at all, only exists for a short time. Flammable substances are not normally present in the air, but can be released under exceptional circumstances, such as accidents or technical faults.
This zoning serves to clearly define the degree of hazard and ensure that appropriate safety precautions are taken to minimize the risk of explosions as far as possible. It is equally important to define the maximum permissible surface temperature in order to minimize the risk of explosion from hot surfaces.
Dust and gas Ex zones
Classification into ATEX zones is based on the duration of the presence of potentially explosive atmospheres. There are two main types of zones: gas Ex zones (0/1/2) and dust Ex zones (20/21/22). The categories are comparable: Zone 0/20 describes areas in which an explosive atmosphere occurs permanently or over long periods of time. In zone 1/21, this hazard occurs occasionally during normal operation, while in zone 2/22 an explosive atmosphere either does not occur at all or only for a short time during normal operation.
- Zone 20: An area in which combustible dust accumulates continuously, frequently or for long periods in the air, which can form an explosive atmosphere.
- Zone 21: An area in which combustible dust may occasionally accumulate in the air during normal operation, creating a risk of explosion.
- Zone 22: An area in which there is usually no accumulation of hazardous dust in the air during normal operation, but if there is, then only for a short time and not regularly.
ATEX zones and device groups
In addition to the zone classification, there is also a classification of the appliances that can be used according to the necessary safety requirements. This categorization is based on the risk assessment: Category 1 is suitable for Zone 0 (or 20 for dust), Category 2 for Zone 1 (or 21 for dust) and Category 3 for Zone 2 (or 22 for dust). This classification ensures that only suitable and certified electrical appliances are used in the corresponding classified areas. According to Directive 2014/34/EU (ATEX), there are three device groups and different categories. Equipment group I concerns potentially explosive atmospheres underground, while group II and class III deal with potentially explosive atmospheres above ground. The categories M1, M2, 1, 2 and 3 within these groups each define the safety level and the degree of protection.
Potentially explosive atmospheres in zone 0
According to the standards, a potentially explosive atmosphere is classified as Zone 0 or Zone 20, depending on the type of hazardous substances and the frequency of the explosive atmosphere during operation. Zone 0 includes areas in which a hazardous mixture of air and flammable gases, vapors or mists is present continuously or for long periods of time. The decision as to whether an area is assigned to this zone depends on whether an explosive atmosphere is present for more than 50 % of the operating time of an installation.
Generally, such areas are found inside plant components, such as pipes and containers. Meanwhile, zone 20 is defined as a place where a potentially explosive atmosphere in the form of a dust cloud is present continuously, for long periods or frequently.
Safety measures in ATEX Zone 0
In ATEX Zone 0, employers must take specific safety measures to ensure the health and safety of employees. These include the selection of suitable equipment and protective systems in accordance with defined criteria and compliance with minimum safety and health regulations. It is important to consider the probability, duration and occurrence of explosive atmospheres and to take preventive measures against explosions. Furthermore, potential ignition sources and electrostatic discharges must be assessed.
Proper labeling of all areas where explosive atmospheres may occur is also required, as is the preparation of an explosion protection document. All equipment used in these areas must bear the ATEX marking and have an EU Declaration of Conformity, including information such as manufacturer details, CE marking, equipment type and category.
Measures in ATEX Zone 0 include
- Selection of suitable devices and protection systems
- Compliance with minimum safety and occupational health regulations
- Consideration of the probability, duration and occurrence of explosive atmospheres
- Taking preventive measures against explosions
- Evaluation of potential ignition sources and electrostatic discharges
- Proper labeling of potentially explosive atmospheres
- Creation of an explosion protection document
- Use of devices with ATEX marking and EU Declaration of Conformity
SERAFIMA: Your partner for explosion protection in industry
At SERAFIMA, we develop reliable solutions for various industries worldwide. Whether you need industrial and explosion-proof centrifugal fans for ATEX zone 0, spare parts or comprehensive advice, our experienced team is on hand to provide you with advice and support. With over 20 years of experience in providing customized solutions for process gas systems in the chemical, petrochemical and steel industries, we are your manufacturer-independent full-service partner. Place your trust in our expertise – together we will ensure your success.
Do you need more information? Give us a call or send us an e-mail and we will be happy to help your company at any time.
Frequently asked questions (FAQ)
What defines ATEX Zone 0?
ATEX Zone 0 designates an area in which an explosive atmosphere consisting of a mixture of air and flammable gases, vapors or mists is present continuously, for long periods or frequently.
What characterizes Ex Zone 1?
Ex Zone 1 describes an area in which an explosive atmosphere in the form of a mixture of air and flammable gases, vapors or mists is likely to occur occasionally during normal operation.
What size is an Ex Zone?
The size of an Ex zone can vary depending on the environment and the source of danger. There is no fixed explosion limit, but the zone is defined based on the source of danger and its potential impact on the environment.
What is an ATEX area?
ATEX areas are defined zones in industrial environments where there is a risk of an explosive atmosphere. They are classified according to the ATEX directives and require specific safety measures and the use of suitable equipment and protective systems to ensure the health and safety of employees.