Friday, 11 November 2016

Hazardous Areas Classification - European Standard

Hazardous Areas Classification - European Standard

European hazardous area classification in zones, protection types, temperature codes and codes

In Europe and most of the world outside North America hazardous areas are classified with the Zone system - where
  • Zones - defines the general nature (or properties) of the hazardous material - if its gas or dust, and the probability of the hazardous material in the surrounding atmosphere
  • Groups - defines the type of the hazardous material and (partly) the location of the surrounding atmosphere
The Zone area classification system is based on the International Electrotechnical Commission IEC 60079 Explosive atmospheres.
In North America hazardous areas are classified by the Class/Division system - or by a Zone system adapted to the IEC standards.

Zones

A Zone defines the general nature - if it is a gas or dust - and the probability of hazardous material being present in an ignitable concentration in the surrounding atmosphere. The Zone system has three levels of hazard for gas or dust.
Gases, Vapors and Mists
IEC 60079-10.1 Classification of areas - Explosive gas atmospheres
ZoneNature and Probability of Hazard Material
Zone 0 Ignitable concentrations of flammable gases or vapors which are present continuously or for long periods of time.
Zone 1 Ignitable concentrations of flammable gases or vapors which are likely to occur under normal operating conditions.
Zone 2 Ignitable concentrations of flammable gases or vapors which are not likely to occur under normal operating conditions and do so only for a short period of time.
Dusts
IEC 60079-10.2 Classification of areas - Combustible dust atmospheres
ZoneNature and Probability of Hazard Material
Zone 20 An area where combustible dusts or ignitable fibers and flyings are present continuously or for long periods of time.
Zone 21 An area where combustible dusts or ignitable fibers and flyings are likely to occur under normal operating conditions.
Zone 22 An area where combustible dusts or ignitable fibers and flyings are not likely to occur under normal operating conditions and do so only for a short period of time.
Zones compares to classes and divisions in the North American Class/Division system.

Group

Group define the type of hazardous material and (partly) the location of the surrounding atmosphere. Group is divided in three groups where group I is reserved for mining locations.
GroupType of Hazardous Material and Location of Atmosphere
Group I
Mines
susceptible to firedamp (flammable mixture of gases naturally occurring in a mine).
Group II
Explosive gas atmosphere other than mines susceptible to firedamp. Group II equipment is subdivided into three subgroups.

A Atmospheres containing propane, acetone, benzene, butane, methane, petrol, hexane, paint solvents or gases and vapors of equivalent hazard.

B Atmospheres containing ethylene, propylene oxide, ethylene oxide, butadiene, cyclopropane, ethyl ether, or gases and vapors of equivalent hazard.

C Atmospheres containing acetylene, hydrogen, carbon disulphide or gases and vapors of equivalent hazard.
Group III
Explosive dust
atmosphere. Group III equipment is subdivided into three subgroups.

A Atmospheres containing combustible flyings.

B Atmospheres containing non-conductive dust.

C Atmospheres containing conductive dust.

Example - Hazardous Area Classification

A room with a propane gas installation will typically be classified as
  • Zone 2, Group IIA

A petrol pump will typically be classified as
  • Zone 1, Group IIA

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