ExECFlameproof Fundamentals: A Complete Guide to Hazardous Area Equipment
Learn the fundamentals of flameproof and explosion-protected electrical equipment, including Ex d, hazardous area zones, gas groups, temperature classes and IP ratings.
Electrical equipment installed in hazardous areas requires special protection because flammable gases, vapours, dust or fibres may be present in the surrounding atmosphere.
A normal electrical device can produce sparks, arcs or hot surfaces during operation. In a hazardous atmosphere, these may become potential ignition sources.
Explosion-protected equipment is therefore designed using specific protection techniques intended to prevent electrical equipment from becoming an ignition source.
One of the most widely used protection techniques in industrial applications is flameproof protection, commonly identified by the marking Ex d.
What is a hazardous area?
A hazardous area is a location where an explosive atmosphere may be present in sufficient quantity to require special precautions for the construction, installation and use of electrical equipment.
Hazardous areas are commonly encountered in industries such as:
- Oil and gas
- Petrochemical plants
- Chemical manufacturing
- Pharmaceutical manufacturing
- Paint and solvent processing
- Petroleum storage
- Refineries
- Fertilizer plants
- Hydrogen installations
- Distilleries
- Grain and powder handling facilities
What is flameproof protection?
Flameproof protection is a method in which components capable of igniting an explosive atmosphere are enclosed inside a specially designed enclosure.
If an explosion occurs inside the enclosure, the enclosure is designed to withstand the internal pressure and prevent the explosion from propagating into the surrounding hazardous atmosphere.
This protection concept is generally identified by the symbol:
Ex d
Modern equipment markings may use designations such as Ex db depending on the applicable standard and equipment protection level.
Understanding hazardous area zones
Hazardous areas are classified according to how frequently and for how long an explosive atmosphere is expected to occur.
For gases and vapours:
- Zone 0 – explosive atmosphere is present continuously, for long periods or frequently.
- Zone 1 – explosive atmosphere is likely to occur occasionally during normal operation.
