Page 42 - OHS, April/May 2025

C O M B U S T I B L E D U S T
Myth vs. Fact: Understanding Combustible Dust and
Dust Collectors
Clearing the air on common myths about combustible dust hazards and how NFPA
standards and explosion protection systems can help facilities stay compliant and safe.
BY BRIAN RICHARDSON
during processes like handling, transferring, packaging or pro-
If your facility handles materials or powders that produce dust
cessing, you may face the risk of a combustible dust explosion.
Th ese explosions happen when a dense cloud of combustible dust
ignites in a confi ned space. Th e initial explosion, known as the prima-
ry explosion, typically occurs in an isolated area. However, the result-
ing pressure can dislodge settled dust in the facility, triggering more
widespread and destructive multilevel advancements of explosions.
Combustible Dust Incident Statistics
Recognizing the materials commonly involved in dust explosions
and fi res is essential for ensuring workplace safety.
DustEx Research Ltd. has recorded 263 fi res, 53 explosions, 94
injuries and 62 fatalities around the world related to combustible
dust between January 1, 2023, and January 1, 2024.
From the global incident data, food and wood products ac-
counted for 79 percent of the fi res and explosions recorded, 76 per-
cent of the injuries and 24 percent of the fatalities. Dust collectors
accounted for 13 percent of combustible dust fi res and explosions
in 2023.
Loss history from dust explosions in the United States from
2016 through 2023 shows an average of 28 dust explosions per
year, 25 injuries and a range from one to six yearly fatalities over
the last eight years. Dust fi res are excluded in this analysis of dust
explosions.
Separating Combustible Dust Myths From Facts
Understanding the realities of dust control and explosion risks is
essential for maintaining a safe and compliant facility. Th e follow-
ing “Myth vs. Fact” section dispels common misconceptions and
provides accurate insights for eff ectively managing hazardous dust.
Myth: Hazardous dust is easy to see and identify.
Fact: Many airborne dust particles in plants and factories are
too small to be seen with the naked eye. Industrial dust collectors
are designed to capture and contain these minute harmful parti-
cles. Th ey achieve this by cycling the dust-laden airstream through
fi lter cartridges, which trap the dust and release clean air back
into the environment. Th ese collectors are typically large pieces of
equipment, located either inside or outside the facility.
Myth: Explosions in dust collectors are rare and random, so
there’s no need to worry about them.
Fact: Explosions can occur in any dust collector when a concen-
trated cloud of combustible dust is suspended in the system. A spark
or ember, oft en from production processes, static electricity or other
ignition sources, can ignite the dust cloud, triggering an explosion.
Proper maintenance and safeguards can mitigate these risks.
For example, active explosion protection devices aim to prevent
explosions by detecting and responding to potential incidents before
or during their occurrence. Passive explosion protection systems ac-
tivate aft er an explosion begins, working to control the event, there-
by safeguarding employees and minimizing equipment damage.
Myth: Dust collector explosions can always be prevented.
Fact: While it’s not always possible to prevent explosions in
dust collectors, systems can be implemented to ensure they don’t
cause harm. Explosion protection systems such as explosion vent-
ing, isolation valves and safety monitoring fi lters are critical for
mitigating incidents. Th ese systems, guided by National Fire Pro-
tection Association (NFPA) standards, help ensure that any explo-
sion is safely contained within the dust collector rather than in
open facilities, protecting personnel and infrastructure.
Th e new NFPA 660: Standard for Combustible Dusts, eff ective
December 6, 2024, is a comprehensive standard that consolidates
most existing NFPA regulations related to combustible dust into a
single, unifi ed guideline. By merging six separate NFPA standards,
NFPA 660 aims to simplify compliance and provide clear, action-
able guidance. It will include both fundamental principles and in-
dustry-specifi c requirements to help facilities manage combustible
dust risks and enhance safety against fi res and explosions.
Myth: Explosion vents are unnecessary if collectors are built
robustly.
Fact: Explosion vents are vital safety features. Th ey are the most
commonly used method for protecting industrial dust collectors.
When dust inside the collector combusts, the pressure rises rap-
idly. In such cases, explosion vents open, allowing the pressure and
fl ame front to exit in a safe direction. Th is protects personnel and
minimizes structural damage. Th e current NFPA 68 – Standard on
Explosion Protection by Defl agration Venting outlines specifi c cri-
teria for the design, location, installation, maintenance and proper
use of these venting systems.
Myth: Only certain facilities need to test their dust for com-
bustibility.
Fact: Per NFPA 660, testing is required if you suspect that a
dust could be combustible. It is a common practice to assume your
process dust is explosive unless testing confi rms a 0 Kst (explosi-
bility index) value. If testing indicates combustibility, a dust hazard
analysis (DHA) must be conducted to determine its Kst value and
maximum pressure rise (Pmax). Dust with a Kst value greater than
0 is considered explosive, and most types of dust fall into this cat-
egory. Th e fi ner the dust particles, the greater the explosion risk.
A DHA is essential and is required per NFPA 660 for identify-
ing potential combustion and explosion hazards and determining
the appropriate fi re and explosion protection measures. Addition-
ally, your dust collection equipment supplier will need the Kst and
Pmax values to properly design and size explosion venting or sup-
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