What is ATEX?

ATEX is an abbreviation for "ATmosphere EXplosible".

This is the abbreviated name of the European Directive 2014/34/EU placing on the market of explosion-proof electrical and mechanical equipment, components and protective systems.

Technical definitions:

An explosive atmosphere is defined as a mixture of dangerous substances with air, under atmospheric conditions, in the form of gases, vapors, mist or dust in which, after ignition has occurred or combustion spreads to the entire unburned mixture.

Zone classification:

• Zone 0 - A place in which an explosive atmosphere consisting of a mixture with air of dangerous substances in the forms such as: gas, vapor or mist. Which is present continuously, for long periods or frequently;
• Zone 1 - A place in which an explosive atmosphere consisting of a mixture with air of dangerous substances in the form of gas, vapor or mist is likely to occur in normal operation occasionally;
• Zone 2 - A place in which an explosive atmosphere consisting of a mixture with air of dangerous substances in the form of gas, vapor or mist is not likely to occur in normal operation, but if it does occur will persist for a short period only;
• Zone 20 - A place in which an explosive atmosphere in the form of a cloud of combustible dust in the air is present continuously, for long periods or frequently;
• Zone 21 - A place in which an explosive atmosphere in the form of a cloud of combustible dust in the air is likely to occur in normal operation occasionally;
• Zone 22 - A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is not likely to occur in normal operation but, if it does occur, will persist for a short period only.

Effective ignition source is a term defined in the European ATEX directive as an event which in combination with sufficient oxygen and fuel in gas, mist, vapor or dust form, can cause an explosion. Methane, hydrogen or coal dust are examples of possible fuels.

Effective ignition sources are:

• Lightning strikes;
• Open flames, this varies from a lit cigarette to welding activity;
• Mechanically generated impact sparks;
• Mechanically generated friction sparks;
• Electric sparks;
• High surface temperature;
• Electrostatic discharge;
• Radiation;
• Adiabatic compression. Air is pumped into a vessel and the vessel surface heats up.

Sitomatic controllers are available for ATEX Zone 2.

Warning!

The controllers are no standalone units and the coding is only valid in combination with the right ATEX coding of the complete installation.