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Hazardous Area Ex Concepts
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ATEX Zones
| Gases and Vapours | Dusts | Definitions | Category Atex Gas/Dust |
Equipment Integrity |
| 0 | 20 | Explosive atmosphere is present continuously, frequently or for long periods | 1G 1D |
Safe under normal operation or rare malfunction |
| 1 | 21 | Explosive atmosphere is likely to occur under normal operation | 2G 2D |
Safe under normal operation or rare malfunction |
| 2 | 22 | Explosive atmosphere may occur under abnormal operation and persist for a short period | 3G 3D |
Equipment must be safe under normal operation |
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IEC BS EN Protection Concepts
Electrical
| Symbol | Zones | Standard | Concept | |
| Flameproof | d | 1 and 2 | IEC BS EN 60079-1 | Contains explosion and flame quenched |
| Increased safety | e | 1 and 2 | IEC BS EN 60079-7 | No arcs, sparks or hot surfaces |
| Non-Sparking | nA | 2 | IEC BS EN 60079-15 | No arcs, sparks or hot surfaces |
| Pressurised | p | 1 and 2 | IEC BS EN 60079-2 | Keep flammable gas out |
| Oil immersed | o | 1 and 2 | IEC BS EN 60079-6 | Keep flammable gas out |
| Restrictive breathing | nR | 2 | IEC BS EN 60079-15 | Keep flammable gas out |
| Simple pressurised | nZ | 2 | IEC BS EN 60079-15 | Keep flammable gas out |
| Quartz or sand filled | q | 1 and 2 | IEC BS EN 60079-5 | Contains explosion and flame quenched |
| Encapsulation | ma | 0,1 and 2 | IEC BS EN 60079-18 | Keep flammable gas out |
| Encapsulation | mb | 1 and 2 | IEC BS EN 60079-18 | Keep flammable gas out |
| Enclosed break | nC | 2 | IEC BS EN 60079-15 | Contains explosion and flame quenched |
| Energy limiting | nL | 2 | IEC BS EN 60079-15 | Limit spark energy and surface temperatures |
| Intrinsic safety | ia | 0,1 and 2 | IEC BS EN 60079-11 | Limit spark energy and surface temperatures |
| Intrinsic safety | ib | 1 and 2 | IEC BS EN 60079-11 | Limit spark energy and surface temperatures |
| Intrinsic safety | ic | 2 | IEC BS EN 60079-11 | Limit spark energy and surface temperatures |
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Dust
| Symbol | Zones | Standard | Concept | |
| Enclosure | tD | 20,21 and 22 | IEC BS EN 61241-1 | |
| Pressurisation | pD | 21 and 22 | IEC BS EN 61241-2 | |
| Encapsulation | maD | 20,21 and 22 | IEC BS EN 61241-18 | |
| Encapsulation | mbD | 21 and 22 | IEC BS EN 61241-18 | |
| Intrinsic safety | iaD | 20,21 and 22 | IEC BS EN 61241-11 | |
| Intrinsic safety | ibD | 21 and 22 | IEC BS EN 61241-11 |
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Mechanical
| Symbol | Zones | Standard | Concept | |
| Constructional safety | c | 0,1,2,20,21 and 22 | BS EN 13463-5 | |
| Liquid immersion | k | 0,1,2,20,21 and 22 | BS EN 13463-8 | |
| Pressurisation | p | 1,2,21 and 22 | BS EN 13463-7 | |
| Ignition source control | b | 0,1,2,20,21 and 22 | BS EN 13463-6 | |
| Inherent safety | g | 0,1,2,20,21 and 22 | BS EN 13463-4 | |
| Flow restricting enclosure | fr | 2 and 22 | BS EN 13463-2 | |
| Flameproof enclosure | d | 1,2,21 and 22 | BS EN 13463-3 |
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Gas Groups
Full list of classification can be found in BS EN IEC 60079-20
| Gas Group | Typical Gases |
| I | Methane |
| IIA | Benzene Propane |
| IIB | Ethylene Hydrogen Sulphide |
| IIC | Hydrogen |
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Temperature Class
| Group II Surface | Group I Mining | |
| Maximum surface temperature °C | Temperature Class | Maximum surface temperature °C |
| 450 | T1 | 450°C without coal dust layer |
| 300 | T2 | 150°C with coal dust layer |
| 200 | T3 | |
| 135 | T4 | |
| 100 | T5 | |
| 85 | T6 |
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