What is an Ex d Enclosure?
According to EN60079-1 by CENELEC(European Committee for Electrotechnical Standardization), Ex d (flameproof enclosure) is a type of protection for explosion proof equipment that is designed to work in potentially explosive atmospheres, where flammable gases, vapor, or dust may exist during normal operation.
This type of protection realized explosion-proof protection by providing a special enclosure (designed with flame path) for parts that may generate arc, sparks, or flame to ignite other flammable substances in the surrounding environment.
Flame-path is a series of narrow channels around the enclosure, with flame-path, Ex d flameproof enclosure can prevent transmission of an explosion inside the enclosure outside, relieving the explosion pressure, cooling the flame so that it can not ignite other gases outside the enclosure, and also cooling the surface temperature of the enclosure to a required T rating by other relevant regulations.
External components that will fit into the enclosure are commonly certified independently, either as independent items or as components. However, external components, such as a flameproof cable gland, must maintain the integrity of any Ex d flameproof enclosure.
If the external components are certified as independent parts, they do not need to be included in the certification of the enclosure, if they are certified as components, they must be listed in the certification of the enclosure.
Equipment Protection Level of Ex d
Ex d can further be classified into 3 categories, Ex da, Ex db, Ex dc for different ATEX zones
| Protection | Category of EPL* | Zone of use |
| Ex da | 1 | zone0, zone1, zone2 |
| Ex db | 2 | zone1, zone2 |
| Ex dc | 3 | zone2 |
* EPL = Equipment Protection Level
* Ex da only for gas detectors
Other Types of Protection
- Ex e Increased Safety
- Ex i Intrinsic Safety
- Ex p Pressurised Apparatus
- Ex m Moulding
- Ex o Oil Immersion
- Ex q Powder Filling
- Ex n Protection “n”
- Ex t Protection by Enclosure
