A work environment such as an oil rig or a chemical warehouse is almost always referred to as a hazardous area. A ‘hazardous area’ is a work environment where the atmosphere contains significant quantities of flammable and explosive gases, vapours or dust. This increases the risk of fire and explosion, causing immense damage to equipment and manpower.
Although a layman may refer to all areas with a risk of fire and explosion as hazardous, such workplaces are classified based on the inherent risk. This classification, in turn, defines the kind of equipment used in such areas and also defines the level of safety to be followed for specific kinds of segments.
However, this classification and the method used for classification vary in different parts of the world. But in general, two major classifications are followed worldwide – International Electrotechnical Commission (IEC) divide hazardous areas into different Zones and North American Installations divide them into Classes, Divisions and Groups.
Our product portfolio consists of a range of ATEX-certified products, and we have created an in-depth guide on the IEC classification in our article A complete guide to ATEX certification.
To summarize, IEC classifies hazardous areas into three broad ATEX zones for gas and dust each:
| Gas Zone | Dust Zone | Hazardous area characteristics |
| Zone 0 | Zone 20 | Hazardous atmosphere to be continuously present or present for long periods of time (>1000 hours per year) |
| Zone 1 | Zone 21 | A hazardous atmosphere is possible but unlikely to be present for long periods of time (> 10 > 1000 hours per year) |
| Zone 2 | Zone 22 | A hazardous atmosphere is not likely to be present during normal operations or may be present for short periods of time (<10 hours per year) |
Explosion protection concepts in hazardous areas
Different areas require different kinds of explosion protection. Hence, a variety of methods are used in hazardous areas for explosion protection. However, it is essential to remember, the usage of such methods is largely guided by the zones mentioned above. The higher the risk, the stronger the explosion protection technique.
1. Ex i intrinsic safety
In an intrinsic safety product, the electrical energy within the equipment is restricted to a level which cannot cause heating of the surface or an ignition. Intrinsic safety products come in two varieties:
a) ia – Allows for the occurrence of two faults during operation.
b) ib – Allows for the occurrence of one fault during operation.
2. Ex d flameproof
This kind of equipment may experience an explosion within an enclosure but can withstand the force of an explosion and prevent the transmission of such an explosion into the outside hazardous atmosphere. The opposite is true as well. Ex d flameproof protection method also prevents any explosion or fire in the outer atmosphere from entering the enclosure and coming in contact with the equipment.
3. Ex m encapsulation
In the Ex m explosion protection concept, the equipment that can potentially cause ignition is enclosed within a compound and resin, thus preventing any contact with the explosive atmosphere. In these kinds of equipment, the surface temperature is also limited.
4. Ex e increased safety
These kinds of installations ensure safety against excessive temperatures and sparks from hazardous area electrical equipment. Any equipment that normally causes sparks is excluded from use in this method of protection.
5. Ex p pressurised
As the name suggests, this method of protection controls the pressure in the equipment, so that flammable gases, vapour, dust or fibre cannot enter the equipment and cause ignition. Another method of protection is also used in this kind of protection where a constant flow of air is maintained to dilute any potentially explosive atmosphere.
6. Ex o oil immersion
In this kind of explosion protection method, all equipment with the potential to cause ignition is immersed in a protective liquid or oil. The oil provides an insulation method which can prevent ignition.
7. Ex q powder filling
This kind of protection method works similar to oil immersion, the difference being instead of oil, quartz or glass powder particles are used to avoid the possibility of ignition.
8. Ex n non-sparking
In an Ex n non-sparking protection method, special precautions are taken so that any electrical equipment with the potential of igniting does not fire up in an explosive atmosphere. This is achieved by using non-sparking components, non-incendive components, tightly enclosing the components to prevent ignition and restricting the energy contained in them.
9. Ex s special
This method of protection does not have any specific parameters or construction rules. Any method of protection which can provide explosion protection is included in this group. It can be a single method or a combination of the different methods discussed above.
Explosion protection in hazardous areas is a matter of grave seriousness. Continuous research and development ensures the introduction of advanced equipment to ensure the safety of such areas and more innovation is expected in the coming years.