DEKRA Process Safety

Same Chemical Compound, Similar Particle Size, Same Dust Explosion Properties – Right?

using the right hose for combustible dust vacuuming

Wrong!

In a word, “no”. Amongst the many variables that impact dust explosion behaviours, particle morphology is regularly overlooked as a strong contributor to different properties. Whilst the impact is generally small for some parameters (eg. explosion severity) it can be significant on others (e.g. minimum ignition energy). A project conducted for a global pharmaceutical company perfectly illustrates this point. A process was conducted in two locations yielding a chemically-identical dust. The only difference in processing method was the crystallisation step. This led to two different particle morphology profiles - a needle particle shape and the other yielding an amorphous shape. Even though the particle size distributions were similar, the test results were startlingly different.


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Particles produced in location A

(This image is provided to illustrate the differences in shape between the particles only and does not provide a representation of the particle size distribution)


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Particles produced in location B

(This image is provided to illustrate the differences in shape between the particles only and does not provide a representation of the particle size distribution)


 

Variable Location A Material Location B Material
Particle size (d50; µm) 32.1 19.1
Moisture content (% w/w) 1.5 1.5
MIE (mJ) 40 - 50 3 - 4

Material from plant location B required much more stringent electrostatic precautions than the relative insensitive material produced in location A – even though the materials were chemically identical and exhibited the same (residual) moisture content and broadly similar particle size distributions. The impact of this data was substantial in terms of electrostatic precautions required on the manufacturing plant to prevent ignition sources.

How can DEKRA Process Safety help you?

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