SAFETY IN THE PLANT


DEMYSTIFYING DUST


How dust testing can lead to process improvements and reduce the risk of an explosion


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variety of dusts possess explosible properties, and therefore when certain conditions are met, such


as the dust being dispersed and enclosed and an ignition source being introduced, combustion is likely to occur. Some combustible dusts include fl our, sugar, milk powder, wood, plastics and metal, and countless other variables that must also be considered such as particle sizes and mixtures. That’s why knowing the combustible


properties of the dust handled in your facility is often the fi rst step towards avoiding a devastating dust explosion. Let’s look at three specifi c types of ‘sensitivity’ dust tests, and how documenting certain explosive properties can be used to leverage process adjustments and facilitate explosion prevention eff orts.


20 Liter testing vessel


Minimum ignition temperature of a layer | MIT (layer) -This measures the lowest surface temperature required to ignite a layer of dust.


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How data may be used: Both monitor and mitigate the hot surfaces within a process to ensure they remain under the dust layer’s MIT.


Applicable standards: ‘ASTM E2021,


Standard Test Method for Hot Surface Ignition Temperature of Dust Layers’ & ‘EN 50281-2-1.’


How data is documented: Aluminum plate is heated to various temperatures in which smoke or combustion is observed from the dust sample; the lowest temperature resulting in ignition is the MIT (Layer).


Temperatures of dust layers: Low = <300°C | Med = 300°C - 450 °C | High = >450 °C.


The lower the MIT, the more susceptible it is to combustion from a hot surface.


Minimum ignition temperature of a cloud | MIT (cloud) - Indicates the


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