Ventilator in Ex hazardous areas

Ventilation is one of the fundamental measures of explosion protection, so it is appropriate to dedicate a few words to this topic.
Three basic conditions are required for an explosion to occur: the presence of a flammable substance, which can include gases, vapours, or dust; the presence of air or oxygen; and, of course, an ignition source. To prevent an explosion, at least one of these three conditions must be eliminated, with priority given to preventing the formation of an explosive mixture.

Focusing on gases and vapours, the most effective method – besides ensuring containment – is ventilation. The requirements for ventilation in explosive atmospheres are defined in the standard EN IEC 60079-10-1. According to this standard, the required amount of ventilation must be adjusted based on the known amount of flammable substance leakage. In practice, the air flow rate is not the most crucial parameter. In explosion protection, we are always interested in the air velocity at the point of leakage.

Whenever possible, natural ventilation is preferred, as it is several times more effective than forced ventilation.

A common mistake is failing to consider the density of gases and vapours. If gases or vapours are heavier than air, ventilation must be provided at floor level. If we are dealing with gases or vapours lighter than air, extraction must be provided at the highest point near the ceiling.

Let’s look at two examples:

• In a battery charging room, where hydrogen is generated, extraction must be ensured at the highest point of the room, and this extraction must be controlled. Battery charging is only permitted if air flow is ensured.
• In a paint mixing room, where all vapours are heavier than air, extraction must be provided at the lowest point in the room, i.e, below the workstation.

With proper ventilation, we can significantly contribute to explosion safety, and in some cases, other measures – such as the installation of Ex equipment – may no longer be necessary.

Our seminars on explosion protection at SIQ Ljubljana focus on all the necessary measures for preventing explosions, where you can learn much more.

More information:
Matej Debenc
E-mail: matej.debenc@siq.si
Tel.: +386 1 4778 227