Classification of hazardous areas with an explosive atmosphere

One of the user´s tasks is to classify hazardous areas. There are currently two technical standards: one of which relates to GASES and the other to DUSTS. Hazardous areas are classified in zones according to the frequency and duration of an explosive atmosphere consisting of combustible gas or dusts in the form of a cloud.

Classification of hazardous areas with an explosive atmosphere

Explosive atmosphere consisting of gases:

- Zone 0: a place in which an explosive atmosphere consisting of a mixture with air of flammable substances in the form of gas, vapour or mist is present continuously or for long periods or frequently. (> 1000 h/year)

- Zone 1: a place in which an explosive atmosphere consisting of a mixture with air or flammable substances in the form of gas, vapour or mist is likely to occur in normal operation occasionally. (10 ÷ 1000 h/year)

- Zone 2: a place in which an explosive atmosphere consisting of a mixture with air of the form of gas, vapour or mist is not likely to occur in normal operation but, if it does occur, will persist for a short period only. (0,1 ÷ 10 h/year)

Explosive atmosphere consisting of dusts:

- Zona 20: a place in which an explosive atmosphere in the form of a cloud of combustible dust in air is present continuously, or for long periods or frequently. (> 1000 h/year)

- Zone 21: a place in which an explosive atmosphere in the form of a cloud of combustible dust in air is likely to occur in normal operation occasionally. (10 ÷ 1000 h/year)

- Zone 22: a place in which an explosive atmosphere in the form of a cloud of combustible dust in air is not likely to occur in normal operational but, if it does occur, will persist for a short period only. (0,1 ÷ 10 h/year)

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