Understanding ATEX
ATEX stands for ATmosphères EXplosives. Whether ATEX requirements apply depends on the installation environment and the presence of a potentially explosive atmosphere.
ATEX equipment is needed only where an installation is intended to operate in an ATEX-classified area. The applicable category is determined by the zone classification defined for the installation.
No matter which refrigerant used: a key objective of system design is to prevent the formation of potentially explosive atmospheres.
PLATZHALTER GRAFIK VON SANDY
ATEX Fundamentals
An explosion can occur only when a flammable substance, oxygen and an ignition source are present at the same time.
If one of these elements is removed, an explosion cannot occur. The primary objective is to prevent the formation of a potentially explosive atmosphere. Where this cannot be fully avoided, explosion protection focuses on eliminating effective ignition sources.
PLATZHALTER GRAFIK VON SANDY
ATEX zones
ATEX zone classification for gases and vapours indicates how frequently an explosive atmosphere – defined as a mixture of air with flammable gas, vapour or mist – may be present in a defined area.
- Zone 0 refers to areas where an explosive atmosphere is present continuously, for long periods or frequently.
- Zone 1 covers areas where it can occur occasionally during normal operation, typically near potential release points such as vents, flanges or seal interfaces.
- Zone 2 describes areas where an explosive atmosphere is not expected in normal operation and, if it occurs, it is rare and short-lived, usually linked to abnormal conditions such as a fault or unintended leakage.
PLATZHALTER GRAFIK VON SANDY
Flammable refrigerant ≠ ATEX
The use of a flammable refrigerant alone does not automatically require ATEX equipment.
When using flammable refrigerants, avoiding ATEX zones is a key objective. Refrigerant charge limits, leak detection, mechanical ventilation and installation location are important planning considerations.
For indoor applications, refrigerant charge must always be assessed in relation to room volume and other criteria, such as accessibility of the area, as part of the risk assessment.
The maximum refrigerant charge shown in the illustration is based on refrigerant flammability, in this case flammability class 3.
