Flammable and explosive dusts in industry

Modern industry uses thousands of flammable and explosive substances. The properties of gases and liquid vapours are usually well known and documented. This is why the identification of risks related to their presence in production processes is relatively straightforward. The situation becomes much more complicated in the case of loose material transport, storage or processing. In most cases, seemingly innocuous substances, such as flour, sugar, cocoa, aluminium or wood powders present a serious explosion hazard.

In most cases, the available data do not allow to predict if the substance presents explosion risk. Therefore, it is necessary to conduct appropriate testing to establish the explosive properties of individual substances. It is important that the testing is conducted by an ample notified body. Only then, the results may be a basis for further actions.

Dust explosiveness properties

The most important explosiveness properties to be established during testing are listed below. These values are required to provide an explosion risk assessment and select appropriate protective systems (most importantly – explosion protection).

EXPLOSION CONSTANT (Kst, (dp/dt)max):

maximum rate of pressure increase in a unit of time during the explosions of all explosive atmospheres within the range of a flammable substance in a closed container and under specific testing conditions.

MAXIMUM EXPLOSION PRESSURE (Pmax):

maximum pressure in a closed container during the explosion of an explosive atmosphere measured under specific testing conditions.

MINIMUM IGNITION ENERGY (MIE):

minimum energy required to ignite the most ignitable explosive atmosphere under specific testing conditions.

DUST CLOUD MINIMUM FLASH POINT:

lowest temperature of the hot internal furnace wall required to ignite the dust cloud in the furnace air.

MINIMUM TEMPERATURE OF A T 5mm DUST LAYER:

lowest temperature of the hot surface required to ignite a 5 mm dust layer on the surface.

A list of common flammable and explosive dusts

The list below contains dusts commonly used in industry which present a risk of an uncontrolled explosion.

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