Dust Explosion: Causes, Prevention and Control Measures

This essay discusses the causes, prevention and control measures of dust explosion in industries and workplaces. It highlights the impact of dust explosions and the laws for safety measures. The essay concludes that controlling measures should be taken to eliminate the hazards of dust explosions.

Introduction
The fast detonation of fine particles
hovering in the air often but not always in
an encompassed place is dust explosion. It
can take place where any isolated
powdered explosive material is present in
higher concentrations in the atmosphere or
other gaseous medium which are oxidized.

Combustible dust explosion
Primary dust explosion
Blast wave
Formation of dust cloud
Accumulation of dust
Secondary dust explosion
Heat created from primary
dust explosion sets fire to
dust cloud

Conditions for dust explosion
 Oxidant
Ignition source
Dust dispersion
Dust confinement
Combustible dust

Causes of dust explosion
 Smoldering nests
Hot surfaces
Burning particles
Electrostatic discharge between
two metal electrodes
Electrical apparatus

Smoldering nests
o Smoldering nests are formed from heat caused by friction such as
cutting, by the accumulation of powder, by heating which is linked
with hot work on tools and ducts that contains dust deposits and
by sources of heat that are small.
o According to the tabulation chart of ignition sources implicated in
426 German dust explosions from the year 1965 to 1985 written
by Eckhoff point out that smoldering nests were the most
ubiquitous cause of dust explosions in silos(28%), dryers(29%)
and the ignition source which is used as second most recurrent
source in dust collector explosions(11%) (Eckhoff 2013).
o According to Gummer and Lunn smoldering nests were bad
sources of ignition for dust clouds while flaming nests caused
ignition more rapidly(Fabiano et al 2014). A numerical method is
presented by Krause and Hensel through which non-steady fields
of temperature can be calculated (Murillo et al. 2013).

Electrostatic discharges
 Electrostatic release between two metal
electrodes can be created in a number of ways
such as by release of static electricity, failures in
electric circuits and in switch.
 Echkoff has discussed about the impact of dust
distinction on MIE of ferro-alloys dust (Holbrow
2013). The distinction of dust was specified only
as a percentage of mass better than a random
size in the past which complicated the analysis of
experimental data that was published and
research is required which will be more systematic
to elucidate the précised influence of particular
size.
 Lorenz and Schiebler investigated the
development of temperature as well as pressure in
the spark channel for the duration of its
configuration as well as its expansion (Xu et
al.2013). The cooling of the canal by the thermal
radiation and the reliable ability of a certain

Hot surfaces
 The temperature that is responsible for the hot surface
explosion of dust cloud has been considered as universal
constant for a specific cloud in past.
 Hot surface explosion temperatures of dust clouds which
are minimal differ drastically with scale along with the
geometry of the warm surface related to the dust cloud.
Both distinguished basic understanding and distinguished
testing approach are needed.
 There are certain materials that are susceptible to self
heating and can lead to impulsive blast-off. The principal
chemical reaction is low level oxidation and the materials
which can self heat by oxidation at low temperature are ABS
resin powder as well as activated carbon and other
chemical intermediates (Hedlund, Astad and Nichols 2014).

Reasons for dust explosion in Industries
 The dust collector deals with dust which
is always suspended in air.
The systems are designed to handle
equipments that are produced somewhere
else and the source of ignition may be
secluded from the dust collector.
 Flammable liquids and gases can cause
dust explosion in industries.

Industrial loses due to dust explosion
A study of losses due to dust explosion experienced by companies
warranted by Factory Mutual and its subsidiaries during 1983 till
2006 supplies some insight into the loss trends of explosions
related to dust (Addai, Gabel and Krause 2015).
There were 166 dust ignitions which resulted in $284 million in
loss of property during that period of time (Addai, Gabel and
Krause 2015).
Woodworking experienced the highest number of losses (38.5%)
which is followed by food processing (15.6%) and metal
processing (10.8%) out of those 166 incidents and these three
industries jointly report 65% of the incidents and the rest 35% of
dust explosions extended out among nine other industries (Addai,
Gabel and Krause 2015).

Combustible dust explosions by industry
Food
Wood
 Chemical
Metal
Plastics
Utility (Yuan 2015)
Paper
Non-manufacturing

Sub processes for both impact and
ignition
The explosion of the flying hot
element and the succeeding burning
method.
 The heat transmits to the dust cloud
which in due course determines
whether explosion occurs or not (Mittal
2013).
The creation and premature heating
of the metal element by the impact.

Prevention of dust explosion
Application of full
confinement.
 Ignition isolation
 Partial inerting
 Explosion discharging
 Automatic explosion
prevention

Application of full confinement
The application of full confinement is restricted
because of expensive equipments.
However, the technique is used in a few special
cases such as when the dust is extremely poisonous
and entirely dependable detention is entirely
necessary while present experimental process permit
perfect forecast of maximum achievable ignition
pressures in simple containers with point source
explosion, design of pressure defiant method tools
maybe complicated.
The usage of finite element calculation method
seems to be increased to achieve improvised design.

Ignition isolation
The purpose of ignition isolation is to avoid dust
explosions from scattering from the primary ignition
site to other procedure units.
 The fundamental understanding of flame
transmission and pressure build-up in interrelated
containers is needed for arrangement of presentation
criteria of several types of dynamic and passive
separation tools.
Holbrow presented rational quantitative direction
for the design of consistent process tools based on
restraint and explosion discharging from similar
experiments in the UK (Holbrow 2013).

From the above graph it is denoted that the number of explosions in 2008 was the
highest and the number of explosions in 2004 was lowest. It can be said that the
number of explosions in recent years has decreased in comparison to previous years
(Boskovic, Basu and Amyotte 2015).

Controlling measures of dust explosion in
workplace
Eliminating elements from fuel, ignition source,
air.
Confinement and dispersion to prevent dust
explosion.
Dust control.
Control of ignition.
Explosion relief and venting.
Personal Protective Equipment(PPE).
Well-maintained Local Exhaust Ventilation
(LEV) system.

Controlling measures of dust explosion in
workplace
Presence of dust should be adequately less.
Implement of suitable housekeeping.
Maintenance programs for dust collection
systems.
Filters can control dust explosion.
Vacuuming and wet cleaning methods are
preferable in workplaces to prevent dust
explosion.
Usage of appropriate flame-proof tools or
non-sparking equipments.

Laws for safety measures
UK Health and Safety Executive’s Guide on
Safe Handling of Combustible Dusts should be
followed by the industries.
NFPA 654
Standard for the Prevention of Fire and Dust
Explosions from the manufacturing, processing
and handling of combustible particulate solids
should be pursued by the manufacturing
workplaces.
WSH Council’s Workplace Safety
Health Guidelines on flammable materials
should be given to the workers.

Conclusion
It can be concluded from the essay that dust explosion
should be prevented and controlling measures should be
taken by people in order to eliminate the hazards of dust
explosions. Dust explosions can affect industries,
workplaces, coal mines and other locations because it is
caused by an explosion source or an oxidant or an
explosive dust. It causes tremendous destruction to
equipments, employees who are working in coal mines
and other workplaces. It has been studied that several
industries has suffered a huge loss due to dust explosion.
There are certain control measures to eliminate dust
explosion such as ignition control, control of dust, relief
and venting of explosion and providing training and
awareness to the workers in workplaces.

References
Addai, E.K., Gabel, D. and Krause, U., 2015. Explosion characteristics of three
component hybrid mixtures. Process Safety and Environmental Protection, 98,
pp.72-81.
Boskovic, A., Basu, P. and Amyotte, P., 2015. An exploratory study of explosion
potential of dust from torrefied biomass. The Canadian Journal of Chemical
Engineering, 93(4), pp.658-663.
Eckhoff, R.K., 2013. Influence of dispersibility and coagulation on the dust
explosion risk presented by powders consisting of nm-particles. Powder
technology, 239, pp.223-230.
Fabiano, B., Currò, F., Reverberi, A.P. and Palazzi, E., 2014. Coal dust emissions:
from environmental control to risk minimization by underground transport. An
applicative case-study. Process Safety and Environmental Protection, 92(2),
pp.150-159.
Holbrow, P., 2013. Dust explosion venting of small vessels and flameless
venting. Process Safety and Environmental Protection, 91(3), pp.183-190.
Hedlund, F.H., Astad, J. and Nichols, J., 2014. Inherent hazards, poor reporting and
limited learning in the solid biomass energy sector: A case study of a wheel loader
igniting wood dust, leading to fatal explosion at wood pellet manufacturer. Biomass
and bioenergy, 66, pp.450-459.

References
Mittal, M., 2013. Limiting oxygen concentration for coal dusts
for explosion hazard analysis and safety. Journal of loss
prevention in the process industries, 26(6), pp.1106-1112.
Murillo, O.C., López, O., Perrin, L., Vignes, A. and Muñoz, F.,
2013. CFD modelling of nanoparticles dispersion in a dust
explosion apparatus. CHEMICAL ENGINEERING, 31.
Xu, H., Li, Y., Zhu, P., Wang, X. and Zhang, H., 2013.
Experimental study on the mitigation via an ultra-fine water
mist of methane/coal dust mixture explosions in the presence of
obstacles. Journal of Loss Prevention in the Process
Industries, 26(4), pp.815-820.
Yuan, Z., Khakzad, N., Khan, F. and Amyotte, P., 2015. Risk
analysis of dust explosion scenarios using Bayesian
networks. Risk analysis, 35(2), pp.278-291.

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