There are six types of area classification guide to classify explosion-proof environment:
Type of protection
New Number (IEC) | ||
General rules | EN-60079-0 | |
Oil immersed | Ex “o” | EN-60079-6 |
Pressurization | Ex “p” | EN-60079-2 |
Power filling | Ex “q” | EN-60079-5 |
Flameproof enclosure | Ex “d” | EN-60079-1 |
Increased safety | Ex “e” | EN-60079-7 |
Intrinsic safety | Ex “i” | EN-60079-11 |
Non sparking | Ex “n” | EN-60079-15 |
Encapsulation | Ex “m” | EN-60079-18 |
IEC stands for International Electrotechnical Commission, a non-profit, non-governmental international standards organization that prepares and publishes International Standards for all electrical, electronic and related technologies – collectively known as "electrotechnology".
Equipment group
Place of use | Group | Areas | Representative gas |
Mines susceptible to firedamp | I | Gaseous Mines | Methane |
Surface industries | II A | Surface | Propane |
II B | Ethylene | ||
II B + H2 | Ehtylene, Hydrogen | ||
II C | Hydrogen, Acetylene |
Equipment protection level (gas/dust)
Gas Atmosphere | |
Zone 0 | An area in which the mixture of explosive gas is constantly present (ex. the inside of a fuel tank). |
Zone 1 | An area in which a mixture of explosive gas may be present during the normal operation of the plant. |
Zone 2 | An area in which the mixture of explosive gas is not normally present, but is only present for brief periods of time. |
Dust Atmosphere | |
Zone 20 | An area in which the mixture of explosive powder is constantly present (ex. the inside of fuel tank). |
Zone 21 | An area in which a mixture of explosive powder may be present during the normal operation of the plant. |
Zone 22 | An area in which the mixture of explosive powder is not normally present, but is only present for brief periods of time. |
Temperature class
Temperature class | T1 | T2 | T3 | T4 | T5 | T6 |
Maximum Surface | 450oC | 300oC | 200oC | 135oC | 100oC | 85oC |
Ingress protection (IP)
First figure indicates protection against dangerous access and solid foreign objects | Index | IP | Index | Second figure indicates protection against water penetration |
Non-protected | 0 | 0 | Non-protected | |
Protected against solid objects 50 mm Ø or more | 1 | 1 | Protected against vertically falling water drops | |
Protected against solid objects 12.5 mm Ø or more | 2 | 2 | Protected against vertically falling drops water enclosure tilted up to 15º | |
Protected against solid objects 2.5 mm Ø or more | 3 | 3 | Protected against spraying water up to 60º from vertical | |
Protected against solid objects 1 mm Ø or more | 4 | 5 4 | 4 | Protected against splashing water from any direction |
Dust-protected | 5 | 5 | Protected against jets of water from any direction | |
Dust-tight | 6 | 6 | Protected against powerful jets of water from any direction | |
7 | Protected against immersion | |||
8 | Protected against continuous immersion |
The minimum requirement for Explosion-Proof protection is IP54.
Supermec mostly caters to Ex “d” and Ex “e” types of protection. The table below shows the advantages and disadvantages of the two:
Advantages | Disadvantages | |
Ex “d” | 1. capable of withholding a possible internal explosion and prevent its transmission to the atmosphere outside the housing 2. higher class of protection 3. easily available and cheaper components | 1. maintenance more complicated ( e.g. difficult to change fluorescent tubes) 2. piped plant (where requested) complicated |
Ex “e” | 1. easy installation 2. pleasant appearance 3. safety cut-off switch | 1. high cost of spare parts (components must be Ex type) 2. frequent and costly maintenance (e.g. seal) |