The Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) require employers to control the risks to safety from fire and explosions 

Many workplaces may contain explosive or potentially explosive atmospheres.

Examples include places where work activities create or release flammable gases or vapours, such as vehicle paint spraying, or in workplaces handling fine organic dusts such as grain flour or wood.

Employers must classify areas where hazardous explosive atmospheres may occur into zones.

The classification given to a particular zone, and its size and location, depends on the likelihood of an explosive atmosphere occurring and its persistence if it does. Schedule 2 of DSEAR contains descriptions of the various classifications of zones for gases and vapours and for dusts.

             GASES VAPOURS & MISTS                              DUSTS                            EQUIPMENT CATEGORY

The Employer must undertake a Risk Assessment to identify the zone applicable. To identify equipment suitable for the specified zone the user should check that the equipment supplied is appropriate by reference to

• Classification of the hazardous area zones, shown in the table above

• Temperature class or ignition temperature of the gas or vapour involved according to the table below

Electrical equipment for use in explosive atmospheres should be marked with:

•  CE Mark

•  Explosion protection symbol “Ex” in a hexagon,

•  Symbol of the Group:  I = Mining products, II = Non-Mining products

•  Equipment category number see zoning table overleaf

1 = Category 1

2 = Category 2

3 = Category 3

•  Atmosphere cause indicator

= ‘G’    (concerning explosive atmospheres caused by gases, vapours or mists)

= ‘D’    (concerning explosive atmospheres caused by dust)

= ‘G D’ (concerning explosive atmospheres caused by gas/vapour/mist/dust)

• The symbol EEx to indicate that the product conforms with one or more ATEX standard 

•  Symbols for certain types of optional additional protection

‘o’ oil immersion

‘p’ pressurisation

‘q’ powder filling

‘d’ flameproof enclosure

‘e’ increased safety

‘ia’ or ‘ib’ intrinsic safety

‘m’ encapsulation

•  Explosion groups 1, 11A, 11B, 11C if optional protection d ia, ib or q

•  If temperature rating part of selection criteria a “T” marking, see Temperature Table above.

These indicate limitations to safe use.  Other information necessary for safe use may also be marked.

for example:  II 1 G EEx T4

Non-Mining products, Group II, Category 1 for use in gas/vapour/mist –atmospheres, max temp 135°C

 II 3 D EEx T5

Non-Mining products, Group II, Category 3 for use in dust – atmospheres, max temp 100°C

Employers and those installing equipment should consider the marking and documentation provided with “Ex” equipment when it is being installed.

All products must be also marked with:

•  name and address of the manufacturer,

•  designation of series or type,

•  serial number (if any)

•  the year of construction.