IEC Standards For Explosive Atmospheres

Selection of Devices According to Zones

Devices for use in Zone 0

Intrinsically safe ‘ia’
Flameproof ‘da’.
Encapsulation ‘ma’.
Optical Radiation ‘op is’.
Equipment secured by special protection ‘s’ Ex sa.

Devices for use in Zone 1

Electrical devices allowed for use in Zone 0, or Flameproof enclosure ‘d’ or ‘db’.
Pressurized devices.
Powder filling ‘q’.
Oil immersion “o” or ‘ob’.
Increased safety ‘e’ or ‘eb’.
Intrinsically safe ‘ib’.
Encapsulation ‘mb’.

Devices for use in Zone 2

Electrical devices allowed for use in Zone 0 and Zone 1, or Electrical devices designed particularly for Zone 2 (e.g. type of protection ‘n’) or Flameproof ‘dc’
Increased safety ‘ec’
Intrinsically safe ‘ic’
Encapsulation ‘mc’
Non-sparking ‘nA’
Secured sparking ‘nC’
Restrained breathing ‘nR’
Liquid immersion ‘oc’
Pressurization ‘pzc’
Special protection ‘sc’

Devices for use in Zones 20, 21 and 22

IEC/EN 60079-31 – Explosive atmospheres.

Equipment dust ignition protection by enclosure “t”.

Selection of the device depending on the ignition temperature of the gas / vapour.

It is utmost important to select a device that will not heat up so that it's maximum surface temperature will not reach the ignition temperature of any gas or vapour present around it. In case the electrical device does not support temperature range of ambience, it is ideal to use an electrical device within surrounding temperature range of -20°C to +40°C.

Selection of device depending on grouping of devices.

The grouping of gases and vapors are arranged in the categories of Group 1 and Group 2. The 1st group is related to air containing firedamp (a combination of gases, most of them being methane which is regularly discovered underground in mines). The 2nd group is expected to be used in all other places with possibly explosive environments. Group 2 electrical devices with types of protection ‘d’ and ‘i’ are segregated into device group 2A, 2B or 2C. Electrical devices with type of protection ‘n’ may also likewise be sub-divided on the basis of certain devices or components that they contain.

Construction standards of the device..

IEC/EN 60079-0 - General Requirements
IEC/EN 60079-1 - Flameproof Enclosure ‘d’
IEC/EN 60079-2 - Pressurization ‘p’
IEC/EN 60079-5 - Powder Filling ‘q’
IEC/EN 60079-6 - Oil Immersion ‘o’
IEC/EN 60079-7 - Improved Safety ‘e’
IEC/EN 60079-11 - Intrinsically Safe ‘I’
IEC/EN 60079-15 - Electrical Device type ‘n’
IEC/EN 60079-18 - Encapsulation ‘m’
IEC/EN 60079-28 - Protection of devices and transmission systems using optical radiation
IEC/EN 60079-31 – Protection from dust by enclosure ‘t’