What is an explosive atmosphere (hazardous area)? - Petzl Finland

What is an explosive atmosphere (hazardous area)?

There is a risk of explosion when six conditions are simultaneously met:


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There is a risk of explosion when six conditions are simultaneously met:

1 - Presence of an oxidant: the oxygen in air, for example.

2 - Presence of a combustible substance: flammable substance such as gas, vapor, powder or dust.

Several examples of combustibles:

Gas: methane, acetylene, butane, propane, hydrogen...

Vapors: ethyl alcohol, carbon disulfide, acetone...

Dust: wood, sugar, grain, starch, coal...

3 - Presence of an ignition source, which is a source of energy strong enough to ignite the combustible: this can be in the form of a flame, a spark, or a high temperature.

4 - Presence of combustible airborne substances (gas, dust, aerosols...), propagation factor.

5 - Confined space: for example a vehicle, work space...

6 - An explosive mixture (threshold), which means having attained a concentration of the combustible substance in the air sufficient to make an explosion possible.