ATEX DIRECTIVE 99/92/EC - What is emission degree?

A degree means the identification of the greater or lesser probability that a source can actually emit gases into the atmosphere; the emission degrees, in decreasing order of probability of emission, can be: continuous, first and second. These grades are understood as follows:

• Continuous if the emission is continuous or can occur over long periods in the ordinary operation of process equipment (free surface of a liquid in a basin).
• First if the release may occur periodically or occasionally in the ordinary operation of the process equipment (sampling, drainage, inspection points).
• Secondly, if the emission is not expected in the ordinary operation of the process equipment, but can only occur occasionally and for short periods, e.g. following a fault (flanges, valves, safety vents).

In addition to the degree of emission, the ventilation of the room must also be taken into account. This is referred to as the degree of ventilation and the availability of ventilation.

The emission level of the source, together with the ventilation of the room, influences the hazardousness and consequent classification of an ATEX Zone.