This document summarizes combustible dust incidents and safety practices. It describes several historical dust explosions in industries like grain processing, candy production, and woodworking that killed dozens of workers. Examples from the 2000s are also provided, such as incidents at an Imperial Sugar refinery and several wood mills. The "typical" progression of a dust explosion is depicted in several diagrams. Key safety practices discussed include controlling dust, ensuring electrical equipment is properly rated, implementing dust collection systems, and regularly inspecting and cleaning areas prone to dust accumulation.

1. Combustible Dust
Safety
John Newquist
Draft 4 17 2018

2. Are These Materials Explosive?
sugar
metal
plastic
wood
coal
medicines
Combustible dust in a jar
video

3. Corn Products Explosion
•Jan 3 1924
•42 died
•Starch Dust
•Pekin IL
•Explosion in starch packing
house.
•Dumping buggies of starch
•Low moisture due to cold.

4. Brach’s Candy
•Sep 7, 1948
•18 died
•Spark from electrical
equipment ignited
suspended starch dust
•Open storage of starch.

5. Continental Grain Elevator - 1977
•Westwego, LA
•Grain Elevator
Explosion
•Dec 1977
• Spark ignited grain dust
• The explosion killed 36
people

6. Coal Dust
• Throughout a twenty‐five year
(1980‐2005) study of PRB
coal‐fired power plants, there
were an average of 11 fires or
explosions, 29 injuries, and 5
deaths per year.
• Another study conducted by the
United States Department of
Labor during the 1996‐2009
time period noted 437
workplace coal power‐related
deaths, averaging 33 deaths per
year in the United States..
Will County Power Plant Crusher Building Explosion

7. Buffalo Rock
•1988
•4 dead
•Bullet filling machine
misfires.
•Housekeeping
•Electrical

8. 8
Catastrophic Combustible Dust Incidents since
1995

9. 9
Malden Mills
Methuen, MA
December 11, 1995
37 Injured
Nylon Fiber
1995

10. 10
Firefighting efforts following the explosion at
Malden Mills (Methuen, Massachusetts, December
11, 1995).

11. Ford River Rouge Power Plant
•2/1/1999
•Dearborn , MI
•MIOSHA General Duty
egregious
•$1,500,000 penalty
•Natural gas boiler explosion
triggered secondary coal
dust explosion that had
accumulated on building
and equipment surfaces
•No flame sensing interlock
for the gas lines
Killed six workers and injured 36

12. 12
Combustible Dust Explosions History
Jahn Foundry
Springfield, MA
February 26, 1999
3 dead
9 Injured
Phenolic resin dust

13. 13
Combustible Dust Explosions History
May 16, 2002
Rouse Polymerics
Vicksburg, MS
5 dead, 7 injured
Rubber Dust

14. 14
Combustible Dust Explosions History
• January 29, 2003 - West
Pharmaceutical Services,
• Kinston, NC
–Six deaths, dozens of injuries
–Facility produced rubber
stoppers and other products for
medical use
–Plastic powder accumulated
above suspended ceiling ignited

15. 15
West Pharmaceutical facility destroyed by polyethylene dust

16. 16
Combustible Dust Explosions History
• February 20, 2003 – CTA
Acoustics Corbin, KY
– Seven Workers died
– Facility produced
fiberglass insulation
for automotive
industry
– Resin accumulated
in production area
and was ignited
CSB VIDEO

17. 17
Combustible Dust Explosions History
• October 29, 2003
• Hayes Lemmerz
Manufacturing Plant
–Two severely
burned (one of the
victims died)
–Accumulated
aluminum
dust
–Facility manufactured
cast aluminum
automotive wheels
CBS Video Hayes Lemmerz

18. Chemical Safety Board
• From 2008 to 2012, our board documented,
50 combustible dust accidents that led to 29
fatalities and 161 injuries.

19. Imperial Sugar - 2008
• Feb 7, 2008
• 14 died
• 60 injured
• $180-220 million dollar est. loss
• $7,700,000 Fine – OSHA
Csb video

20. Metal Dust - 2011
• Hoeganaes plant TN
• Four dead, two explosions
• The plant manufactures metal
powder used in the automotive
industry
• CSB and OSHA investigations
• The company issued a
statement saying it has begun
a review “to ensure that we
fully understand the cause of
the fire and have
implemented appropriate
measures to prevent a
recurrence of this incident.”
• “We have already made
significant progress on some
of the issues raised by the CSB
and we won't resume
production until we are
confident that all issues have
been addressed.”

21. Grain Dust Explosion - 2011
•Oct 29, 2011
•Six dead, 2 injured
•Five Willful, 8 serious
•$400,000 penalty
•Settled for $182,000
•Unclassified
•Lawsuit by families

22. Jan 2012
• Babine Sawmill in Burns Lake BC
• 2 dead, 20 injured
• The dust collection system had been
unreliable for months.
• “You couldn’t see across the mill, that’s
how bad the dust levels were,” said
millworker Ryan Clay. “Even with the fans
going full blast, the dust was just
horrendous.”
Friction within the motor-reducer V-belt guard
provided ignition source

23. Apr 2012
• Lakeland Sawmill in Prince
George, B.C.
• 2 dead, 22 injured
• Once again, accumulated wood
dust was identified as the likely
fuel
• “ the dust is so thick it is visible in
the air as hazy, luminescent
dots.”
• “possible ignition have been
located at the conveyor level,
where electrical or mechanical
equipment was being operated in
contained areas.”
• $724,163

24. April 2014
Corrigan TX
Four people remain hospitalized, three in critical condition, after an explosion
and fire at a Polk County plywood mill
• a) dust collector bags impeded the venting area of the dust collector
deflagration vents.
• b) explosion vents releasing in the dust collector without taking measure
to protect employees from the fireball path
• c) dust collector vented and the deflagration traveled upstream to the
sander.
• d) responding to a fire within the sander dust collection system without
the main blower remaining in operation.
• e) responding to a fire within the sander dust collection system without a
choke between the sander dust collector and silo leading to the
briquetter.

25. Result
• $39 Million to survivor
• The suit claimed the wood dust collection system, which included a spark
detection and suppression system, failed to meet numerous industry
standards set by the National Fire Protection Association and FM Global
The jury assigned 51 percent of the fault to Aircon Inc., the company
which designed and installed the dust collection system, 26 percent to
GreCon, manufacturer of the spark detection and suppression system, and
the remaining 23 percent to Georgia-Pacific
• 2014 OSHA investigation of the explosion resulted in fines to G-P of
approximately $14,000 for two serious violations, including the lack of a
choke between the sander dust collector and silo leading to the
briquetter, dust collector bags which impeded the venting area of the dust
collector deflagration vents, and a lack of measures in place "to protect
employees from the fireball path."

26. August 2014
• 75 people were killed
and 185 others injured
after an explosion
ripped through a metal
products factory in
China’s eastern Jiangsu
Province

27. March 2017

28. May 2017
NFPA requires that an explosion isolation
device be installed on all suction side
ducts that transport material with a KST
value above zero.
KST values are used to measure the speed
at which pressure rises during a standard
explosion severity test.
EcoMAXX™ No Return Valve

29. 29
Types of Dust Involved in incidents
Metal
20%
Wood
24%
Food
23%
Other
7%
Plastic
14%
Coal
8%
Inorganic
4%

30. 30
Types of Industries Involved in Dust Incidents
Other
7%
Food Products
24%
Lumber/
Wood
Products
15%
Chemical
Manufact'g.
12%Primary Metal
Industries
8%
Rubber &
Plastic
Products
8%
Electric
Services
8%
Furniture &
Fixtures
4%
Equipment
Manufact'g.
7%
Fabricated
Metal Products
7%

31. 31
Equipment Involved in Dust Explosions
Source: Guidelines for Safe Handling of Powders and Bulk Solids, CCPS, AICHE
Material
US (1985 – 1995) UK (1979 – 1988) Germany (1965 – 1980)
Number of
Incidents
% Number of
Incidents
% Number of
Incidents
%
Dust Collectors 156 42 55 18 73 17
Grinders 35 9 51 17 56 13
Silos/Bunkers 27 7 19 6 86 13
Conveying
Systems
32 9 33 11 43 10
Dryer/Oven 22 6 43 14 34 8
Mixers/Blenders >12 >3 7 2 20 5
Other or
Unknown
84 23 95 31 114 27
Total 372 100 303 100 426 100

32. Dust Collectors
)

33. Blenders/Mixers

34. Grinders and Mills

35. Conveyors

37. 37
The “Typical” Explosion Event
Process
Equipment
Initial
Internal
Deflagration
Time, msec.
0 25 50 75 100 125 150 175 200 225 250 300 325

38. 38
The “Typical” Explosion Event
Process
Equipment
Initial
Internal
Deflagration
Shock Wave
Time, msec.
0 25 50 75 100 125 150 175 200 225 250 300 325

39. 39
The “Typical” Explosion Event
Process
Equipment
Initial
Internal
Deflagration
Elastic Rebound
Shock Waves
Time, msec.
0 25 50 75 100 125 150 175 200 225 250 300 325

40. 40
The “Typical” Explosion Event
Time, msec.
0 25 50 75 100 125 150 175 200 225 250 300 325
Process
Equipment
Initial
Internal
Deflagration
Dust clouds caused
by Elastic Rebound

41. 41
The “Typical” Explosion Event
Process
Equipment
Containment
Failure from Initial
Deflagration
Dust Clouds Caused
by Elastic Rebound
Time, msec.
0 25 50 75 100 125 150 175 200 225 250 300 325

42. 42
The “Typical” Explosion Event
Process
Equipment
Secondary Deflagration
Initiated
Dust Clouds Caused
by Elastic Rebound
Time, msec.
0 25 50 75 100 125 150 175 200 225 250 300 325

43. 43
The “Typical” Explosion Event
Process
Equipment
Secondary Deflagration
Propagates through Interior
Time, msec.
0 25 50 75 100 125 150 175 200 225 250 300 325

44. 44
The “Typical” Explosion Event
Process
Equipment
Secondary Deflagration
Vents from Structure
Time, msec.
0 25 50 75 100 125 150 175 200 225 250 300 325

45. 45
The “Typical” Explosion Event
Secondary Deflagration
Causes Collapse and Residual Fires
Time, msec.
0 25 50 75 100 125 150 175 200 225 250 300 325
Diagrams Courtesy of John M. Cholin, P.E., FSFPE, J.M. Cholin Consultants, Inc.

46. Electrical Classification
• All Equipment should be check to see if rated for Class II locations.

47. Dust Control
Minimize the escape of dust from process equipment or ventilation
systems;

48. Dust Control
• Use dust collection systems and filters;

49. Dust Control
• Utilize surfaces that minimize dust accumulation and facilitate cleaning;
Good Not good

50. Dust Control
• Provide access to all hidden areas to permit inspection;

51. Dust Control
• Inspect for dust residues in open and hidden areas, at regular intervals;

52. Dust Control
• Clean dust residues at regular intervals;

53. Dust Control
• Use cleaning methods that do not generate dust clouds, if ignition
sources are present;

54. Dust Control
• Only use vacuum cleaners approved for dust collection
• Typically sold as “Explosion Proof Industrial Vacuum Cleaners”

55. Dust Control
• Locate relief valves away from dust hazard areas; and
Vent in a safe location

56. Dust Control
• Develop and implement a hazardous dust inspection, testing,
housekeeping, and control program (preferably in writing with established
frequency and methods).

57. Accumulation
• Production
• Packaging
• Process
• Horizontal surfaces
• Floors

58. Hidden Areas
Beams
False Ceilings
Ducts
Piping

59. Dispersion
Mechanical
Vibration
Ventilation

60. Ignition Control
• Use appropriate electrical equipment and wiring methods;
Housekeeping
needs to be kept up

61. Ignition Control
• Control static electricity, including bonding of equipment to ground;

62. Ignition Control
• Control smoking, open flames, and sparks;

63. Ignition Control
• Control mechanical sparks and friction;
Firefly spark
detection
video

64. Ignition Control
• Use separator devices to remove foreign materials capable of igniting
combustibles from process materials;
Mag separator video

65. Ignition Control
• Separate heated surfaces from dusts;

66. Ignition Control
• Separate heating systems from dusts;

67. Ignition Control
• Proper use and type of industrial trucks;

68. Damage Control
• Separation of the hazard (isolate with distance);
Put dust collector outside if possible

69. Damage Control
• Jan 2018
• Fire in duct
• Clogged by large piece
• Roof panels blew. Low amount of dust.
• Outage 36 hours.

70. Damage Control
• Deflagration venting of a building, room, or area;

71. Damage Control
• Pressure relief venting for equipment;
Flameless venting

72. Damage Control
• Provision of spark/ember detection and extinguishing systems;

73. Damage Control
• Explosion protection systems (also refer to NFPA 69, Standard on
Explosion Prevention Systems);

74. Damage Control
• Sprinkler systems;

75. Management
• Prevention through design
• Trade Shows
• Facility analysis
• Periodic Audits
• Prevention and protection
program.
• Plant dust housekeeping
• Ignition control
• Monetary resources
• Training for Employees

76. The Walkaround

77. Sample OSHA Questions
• What is the Plant’s
Housekeeping program?
• Is there dust accumulation
of 1/32 inch thick?
• Dust collectors located
inside of buildings?
• Explosion relief venting
distributed over the
exterior walls of buildings
and enclosures?

78. Sample OSHA Questions
• Does the facility have
isolation devices to prevent
deflagration propagation
between pieces of
equipment connected by
ductwork?
• Does the facility have an
ignition control program,
such as grounding and
bonding?
Fire through a duct is bad

79. Sample OSHA Questions
• Are Vacuum cleaners
used in dusty areas and
approved for the hazard
classification?
• Are separator devices
to remove foreign
materials used?
• Can tramp metal ignite
combustible dusts in
the dust collection
systems? Check the label for Class II

80. Sample OSHA Questions
• Is the exhaust from the
dust collectors
recycled?
• Does the dust collector
system have spark
detection and
explosion/deflagration
suppression systems?

81. Sample OSHA Questions
• Are ducts designed to maintain
sufficient velocity to ensure the
transport of both coarse and fine
particles?
• What is the design basis for the
ventilation?
• Are duct systems, dust collectors,
and dust-producing machinery
bonded and grounded to minimize
accumulation of static electrical
charge?

82. Sample OSHA Questions
• Is metal ductwork used?
• Are bulk storage containers
constructed of
noncombustible materials?
• Are employees trained in
the hazards of the
combustible dust?
• Are MSDSs for the
chemicals which could
become combustible dust
under normal operations
available to employees?

83. 83
Housekeeping
• OSHA
1910.22(a)(1) - All places of employment, passageways, storerooms, service rooms, and
walking-working surfaces are kept in a clean, orderly, and sanitary condition.

84. Housekeeping

85. Housekeeping

86. 86
Dust Layer Thickness Guidelines
• 1/8” in grain standard
• Rule of thumb in NFPA 654
–1/32” over 5% of area
–Bar joist surface area
equals about 5% of floor area
–Max 20,000 SF
–Idealized

87. 87
Dust Layer Thickness Guidelines

88. 88
Dust Layer Thickness Guidelines

89. Electrical Classification
• “if the workplace has a Class II location, then citations under 29 CFR
1910.307 may be issued to those employers having electrical equipment
not meeting the standard’s requirements. “
Class 2 HVAC

90. Electrical Classification

91. $53,900

92. Flame Resistant Clothing
Citations under 1910.132(a) (the general requirement to provide and assure the use
of protective equipment, including protective clothing) may be issued, if an
employee exposure to potential burn injuries can be documented.

93. Flame Resistant Clothing

94. Forklifts
• Forklifts can be an ignition
source in dusty
environments

95. Forklifts
$42,350

96. Training
• 1910.272(e)(1)(i) General safety precautions associated with the facility,
including recognition and preventive measures for the hazards related to
dust accumulations and common ignition sources such as smoking; and,
• 1910.272(e)(1)(ii) Specific procedures and safety practices applicable to
their job tasks including but not limited to, cleaning procedures for
grinding equipment, clearing procedures for choked legs, housekeeping
procedures, hot work procedures, preventive maintenance procedures
and lock-out/tag-out procedures.

97. Training

98. Training
• July 7 2010 Imperial Sugar Settlement agreed to 5 training points
• 1. The physical hazards and hazardous properties including, but not
limited to, combustibility and explosivity of sugar, powdered sugar,
cornstarch and coal dusts
• 2. The prevention and mitigation of combustible dust hazards including,
but not limited to, dust accumulation, ignition sources, and housekeeping
• 3. The specification, ordering, development of electrical classification
drawings, installation, maintenance and control of change of electrical
equipment, with an emphasis on approved electrical equipment for
hazardous classified areas designated in OSHA’s standards at Subpart S –
Electrical
• 4. The hazard recognition and reporting of electrical equipment which is
not properly installed or maintained, e.g., unapproved extension cords or
box fans in hazardous locations, frayed electrical conductors on a product
machine, the addition of an “ordinary” light fixture in a hazardous
classified area, etc.
• 5. Reasons for wearing fire retardant clothing

99. Written Programs

100. Written Programs
$6160
Potential ignition sources

101. Hot Works
• Around collection points and
ductwork or in areas where
hazardous levels of dust
accumulations may occur
• In section 5(a)(1) cases a hot
work permit system may be
noted as a feasible abatement
method.

102. Hot Works
• Use Alternatives
• Analyze the Hazards
• Monitor the Atmosphere
• Test the Area
• Use Written Permits
• Train Thoroughly
• Supervise Contractors

103. Typical 5(a)(1) Violations
• Ducts and system were
not grounded

104. Grounding
All equipment used in the
dust generating process
must be thoroughly
grounded to remove static
electricity.
“Recommended Practice on
Static Electricity,” NFPA 77,
should be followed.
Inspection and cleaning of all electrical equipment must be done regularly and
frequently (at least weekly).
Ground connections should be checked visually on a daily basis by the
operators.

105. Bonding and Grounding

106. Typical 5(a)(1) Violations
• Compressed Air was
used for cleaning
• Tip: Clean fugitive dust
• Regular program
• Access to hidden areas
• Safe cleaning methods
• Maintain dust free as possible
• No blow down unless All
electrical power and
processes have been
shutdown and other means
cannot work.
• See NFPA

107. Compressed air

108. Typical 5(a)(1) Violations
•Dust collectors inside

109. Dust Collectors

110. Typical 5(a)(1) Violations
• Explosion Vents in bad
locations

111. Explosion Venting
$7000

112. Typical 5(a)(1) Violations
• No Spark detection

113. Spark Detection
$7000

114. Typical 5(a)(1) Violations
• Systems were not
provided to prevent
deflagration
propagation from
dust collectors to
other parts of the
plant.
October 29, 2003 - Hayes Lemmerz
Manufacturing Plant, IN
Shawn Boone, 33, died in the
Aluminum Dust explosion

115. Typical 5(a)(1) Violations
• Not maintaining duct
velocity
• Aluminum Conveyor
velocity might be 4500
ft/min for pneumatic
conveyors

116. Typical 5(a)(1) Violations
• No explosion relief
venting distributed
over the exterior
walls and roofs of the
buildings.
CTA Acoustics 2003 – 7 dead
Fiberglass fibers and excess phenolic resin
powder probably went to the oven while
workers were using compressed air and
lance to break up a cogged bag house
filter

117. Typical 5(a)(1) Violations
• Airborne fugitive dust

118. Typical 5(a)(1) Violations
• A means of tramp metal
protection was not
provided to keep any
unwanted metal
fragments out of the
air-material separators
From Duramag

119. Typical 5(a)(1) Violations
• Excessive dust
• Not cleaning per the
appropriate NFPA
Standard

120. Strategy for Employers
• Test for Combustible
Dust
• Find Applicable NFPA
standards
• Implement a Safety
Management System
• Housekeeping
• Electrical Classification
• Conduct Process Hazard
Analysis for Dust
Generation Processes
• Control Ignition sources
• Develop safety
procedures for working
on dust collectors
• Investigate leaks, hot
spots, near misses
• Train Employees in
hazards of combustible
dust
• Plan for fires and
emergencies