In the chemical and petrochemical industries, industrial processes, oil rigs and military installations there are materials which are stored, processed or produced in areas where the atmosphere is potentially explosive and in which explosion-proof heating elements are required.
From July 2003, all equipment used within the European Community has to comply obligatorily with Directive Atex 94/9/CE. All the equipment contained in this catalogue is certified on the basis of Directive Atex 94/9/CE.
Generalities
For the purposes of Directive 94/9/CE, an explosive atmosphere is defined as a mixture:
a) of inflammable substances in the form of gases, steam, clouds or dust;
b) with the air;
c) in the atmospheric conditions;
d) in which, after igniting, combustion spreads to the total amount of the nonburnt mixture (it is necessary to point out that combustion does not always consume all the dust, if there is any)
For an explosion to occur, the following circumstances have to coincide:
• Presence of oxygen in the air.
• Presence of an inflammable substance in the form of gas, steam, cloud or dust.
• A sufficient source of energy, such as an electric arc or a specific rise in temperature.
Atmospheric conditions are understood as being when the temperature falls between -20°C and +40°C and pressure is on the 0.8 bar to 1.1 bar band
Al electrical material to be installed in this type of atmosphere must be designed and constructed so that its energy output does not produce the expected explosion, or that this is controlled.
The European Community has issued the Directive ATEX 94/9/CE and standards which require the user to assess the explosion risk, bearing in mind the possibility of the presence of said atmospheres, their degree of danger, presence of energy sources, processes and their interactions, installation of equipment and its potential consequences.
If a risk exists, the user must:
1. Prevent formation of potentially explosive atmospheres. If that is not possible,
2. Prevent ignition. If that is impossible,
3. Reduce the effects of the explosion in such a way that the risk is eliminated.
ATEX Marking
Grup and Category of equipments
Classification of the dangerous zones (According to EN 60079-10)
Explosive atmospheres are classified by zones. Classification by zones depends on the time and spatial probability of a dangerous explosive atmosphere occurring.
Groups of gases
