ATEX = »ATmosphere Explosive«
- Since 1 July 2003, two new standards related to safety in potentially explosive atmospheres have been in force within the European Union:
- ATEX 137 (1999/92/EC): Defines safety measures for the protection of contractors working in potentially explosive atmospheres.
ATEX 95 (94/9/EC): Defines the requirements for devices operating in such potentially explosive atmospheres.
The directive (94/9/EC) also covers safety, monitoring and control devices intended for use outside the potentially explosive atmospheres but which are nevertheless required or useful for the safe operation of devices or safety systems in terms of explosion hazards.
Frequently used terms:
- Equipment is defined as machines, devices, attached or mobile units, control components with their accessories, and detection and prevention systems, the purpose of which is – separately or jointly – to create, transfer, store, measure, control and convert energy and/or process materials and may cause an explosion with their own potential ignition sources
- Safety systems are defined as complete units designed to momentarily suppress incipient explosions and/or limit the effective range of flames and explosion pressure. Safety systems may already be built into the equipment or can be sold as separate autonomous systems.
- Components are defined as individual parts necessary for the safe operation of equipment and its safety systems, but which have no autonomous function.
- An explosive atmosphere contains highly flammable substances in the form of gases, vapor, droplets, or dust mixed with air in atmospheric conditions in which the flames upon ignition will spread to the rest of the flammable mixture.
- A potentially explosive atmosphere is defined as an atmosphere that may become explosive because of local or working conditions.
Equipment groups and categories:
- The group Equipment I includes equipment intended for use in underground sections of mines and in surface mining machines that are vulnerable to firedamp and/or flammable dust.
- The group Equipment II includes equipment intended for use on other sites where an explosive atmosphere may pose a threat.
According to rules on explosion protection, areas protected against explosion are classified into explosion hazard zones based on the frequency or probability of occurrence and duration of the explosive atmosphere:
- Zone 0: Area in which explosive atmosphere comprised of a mixture of air and flammable substances in the form of gas, vapour or fog is present at all times, for longer periods, or frequently.
- Zone 1: Area in which an explosive atmosphere comprised of a mixture of air and flammable substances in the form of gas, vapour or fog may occasionally be present during the course of normal operation.
- Zone 2: Area in which an explosive atmosphere comprised of a mixture of air and flammable substances in the form of gas, vapor, or fog is not present during normal operation, and if it is, it is only there for a short period of time.
- Zone 20: Area in which explosive atmosphere in the form of airborne combustible dust is present at all times, for longer periods or frequently
- Zone 21: Area in which an explosive atmosphere in the form of airborne combustible dust may occasionally be present during normal operation
- Zone 22: Area in which an explosive atmosphere in the form of airborne combustible dust is not present during normal operation, and if it is, it persists only for a short period of time.