General classification of hazardous areas
Classification according to technical regulations implies dependence on the frequency and duration of equipment stay in the hazardous area and is divided into classes from 0 to 2 and from 20 to 22.
Class 0 is the most difficult class, according to which a hazardous mixture may be present near the equipment continuously or for one hour.
Class 1 is a weaker class than Class 0. In this class, the vapours or flammable liquids emitted will mix with air to form an explosive mixture.
Class 2 is the weakest class, in which explosive mixtures are not formed, but may be only in case of accidents or other emergency situations.
Class 20 is an area in which the concentration of an explosive mixture (dust) with air is constantly present and the self-ignition limit is not more than 65 grams per cubic metre.
Class 21 is an area that emits a periodically explosive mixture (dust) with air and a self-ignition limit of 65 grams per cubic metre or less.
Class 22 is an area that does not produce explosive mixtures (dust) with air and has a self-ignition limit of 65 grams per cubic metre or less, but may be self-igniting in emergency or other urgent situations.
The classification of equipment by group is categorised as follows:
I is equipment that is used in mines, mines and other areas where it is impossible to escape from a constant concentration of an explosive mixture.
II is equipment that is used indoors or outdoors in hazardous areas.
III is equipment that is used indoors or outdoors in dust-hazardous areas.
In this case, an example of the labelling of explosion-protected equipment can be given, for example: ExmpIICT6,
where Ex is the sign of explosion-protected equipment,
mp – type of explosion protection (in this case combined),
IIC – group classification,
T6 – temperature class.
The classification of equipment by explosion protection level is based on its potential to become a source of ignition. He could be:
- explosion-proof – the most complex class and the most dangerous of the listed classes;
- explosion-proof – medium in complexity and therefore medium in hazard;
- increased explosion protection – the weakest class, implying only an increased degree of dust and moisture protection (explosion protection type Ehe).
Classification according to technical regulations implies dependence on the frequency and duration of equipment stay in the hazardous area and is divided into classes from 0 to 2 and from 20 to 22.
Class 0 is the most difficult class, according to which a hazardous mixture may be present near the equipment continuously or for one hour.
Class 1 is a weaker class than Class 0. In this class, the vapours or flammable liquids emitted will mix with air to form an explosive mixture.
Class 2 is the weakest class, in which explosive mixtures are not formed, but may be only in case of accidents or other emergency situations.
Class 20 is an area in which the concentration of an explosive mixture (dust) with air is constantly present and the self-ignition limit is not more than 65 grams per cubic metre.
Class 21 is an area that emits a periodically explosive mixture (dust) with air and a self-ignition limit of 65 grams per cubic metre or less.
Class 22 is an area that does not produce explosive mixtures (dust) with air and has a self-ignition limit of 65 grams per cubic metre or less, but may be self-igniting in emergency or other urgent situations.
The classification of equipment by group is categorised as follows:
I is equipment that is used in mines, mines and other areas where it is impossible to escape from a constant concentration of an explosive mixture.
II is equipment that is used indoors or outdoors in hazardous areas.
III is equipment that is used indoors or outdoors in dust-hazardous areas.
In this case, an example of the labelling of explosion-protected equipment can be given, for example: ExmpIICT6,
where Ex is the sign of explosion-protected equipment,
mp – type of explosion protection (in this case combined),
IIC – group classification,
T6 – temperature class.
The classification of equipment by explosion protection level is based on its potential to become a source of ignition. He could be:
- explosion-proof – the most complex class and the most dangerous of the listed classes;
- explosion-proof – medium in complexity and therefore medium in hazard;
- increased explosion protection – the weakest class, implying only an increased degree of dust and moisture protection (explosion protection type Ehe).
