Work in explosive atmospheres

Work in potentially explosive atmospheres is regulated by different standards which describes both the workplace and the equipment used in this hazardous environment.

There are basically two EU directives covering work in explosive atmospheres:

  • Directive 1999/92/EC covers the responsibility of the employer.
  • ATEX Directive 94/9/EC covers products and equipment for use in explosive atmospheres.

ATEX is an abbreviation for Atmosphères Explosibles. 

Zones

All workplaces which are determined to be potentially explosive must be classified in zones by the employer. These zones are described in EU Directive 1999/92/EC.

The classification is made on the basis of the frequency and duration of the occurence of an explosive atmosphere. The extent of the measures to be taken is determined by this classification.

Zones 0 and 20 cover the highest explosion risk.

 

Zone - gas

Description:

A place in which an explosive atmosphere consisting of a mixture

with air of flammable substanses in the form of gas, vapor or mist...

0

... is present continuously or for long periods or frequently.

1

... is likely to occur in normal operation occasionally.

2

…is not likely to occur in normal operation but, if it does occur, will persist for a short period only.

Zone - dust

Description:

A place in which an explosive atmosphere in the form of a cloud of combustable dust in air...

20

…is present continuously or for long periods or frequently.

21

... is likely to occur in normal operation occasionally.

22

…is not likely to occur in normal operation but, if it does occur, will persist for a short period only.

Explosion group

Chemicals regarded as explosive are classifed in three groups which are described in the IEC 60079 standard.

Explosion group II C represents the most hazardous chemicals in this respect.

 

Explosion group Description
II A

Biggest group. Methanol, toluene...

II B

Ethylene, ether...

II C

Hydrogen, Acetylene & Carbon disulfide.

  • Last updated 4/18/2013
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