Dust explosions are a significant industrial hazard, with approximately 50 incidents reported annually, leading to numerous fatalities and injuries. A history of various dust explosion events highlights the risks associated with combustible dust from organic and synthetic materials, often causing secondary explosions and widespread damage. Effective firefighting strategies require a thorough understanding of the types of silos and the proper protocols to mitigate the risk of explosions during firefighting operations.

1. Dust Explosions

2. Dust Explosions
Approx 50
explosion are
reported each year
Resulting in
hundreds of deaths
Yet are the least
recognized
Industrial hazard
2

3. Dust Explosions
February 1999, Massachusetts
Iron foundry
A small, primary Resin dust
explosion within the ductwork,
fuelled a secondary explosion,
powerful enough to lift the roof
and cause wall failures.
3 people were killed, and 9 were
injured.
3

4. Dust Explosions
January 2003 – North CarolinaPharmaceutical plant that
manufactures rubber drug
delivery components
A fire and a series of explosions
destroyed the plant with minor
damage surrounding area
6 people killed and 38 injured
including 2 firefighters
4

5. Dust Explosions
February 2003 - Kentucky
insulation manufacturing plant.
Primary blast was ignited by a
small fire while cleaning
A deadly cascade of dust
explosions followed throughout
the plant.
7 people were killed and 37
injured
5

6. Dust Explosions
February 2008 – Georgia
Imperial Sugar refinery
Dust Explosions ripped through
the plant destroying 2 silos and
1 building
Seven days to extinguish
13 people were killed and 17
injured
6

7. Dust Explosions
US Chemical Safety Board (CSB) identified 281
dust fires & explosions between 1980 & 2005
In the USA alone, Dust explosions in the last 25
yrs killed 119 workers and injured 718 others.
Wood & Coal Dust explosions are by far the
leading sources for Explosions
Dust Collection/ Hopper systems are the leading
equipment type for Explosions
7

8. Dust Explosions
Can occur anywhere combustible dust is
produced
Can be almost any organic material
An Explosion be initiated by any energy
source.
Sparks, Friction, Open Flames, Heat
Usually results in secondary explosions
8

9. Dust Explosion Pentagon
Dust Explosion
Pentagon
9

10. Dust Explosions
Rules for dust explosions.
Must be combustible.
Dust cloud must be confined.
Capable of becoming airborne.
Size & distribution = flame spread.
Explosive range 50g/m3 to 23kg/m3
10

11. Dust Explosions
Dust / Powders that CAN Explode
Natural Organic materials (grains, linen,
sugar, coal, peat)
Synthetic Organic materials (pesticides,
plastics, resins)
Metals ( aluminum, zinc, iron)
Any Unstable Oxide
11

12. Dust Explosions
Dust / Powders that WILL NOT Explode
Silicates, Sulphates
Nitrates,Carbonates,Phosphates
Cement, Sand, limestone
Any Stable Oxide
12

13. Dust Explosions
Glass breaks at 50 kpa (7 psi.)
Wood frame at 56-70 kpa (8-10 psi.)
Reinforced concrete 70-85 kpa (10-12 psi.)
FORCE FROM DUST EXPLOSIONS
CAN EXCEED 700 kpa or 100 PSI
13

14. Hopper Fires
14

15. Hopper Fires
Characteristics.
Funnel Shaped
On legs or stilts
Loaded from the
top
Unloads from
the bottom.
15

16. Hopper Fires- Incident Command
Be aware of the
potential for
explosions
Initial Defensive
Strategy
Establish large
“Hot Zone”
Evacuate civilians
to safe distance
16

17. Hopper Fires- Incident Command
Protect exposures
including the
building the hopper
serves
Establish water
supply sufficient
volume for worst
case scenario
Lock out / Tag Out
each power source
17

18. Hopper Fires- Incident Command
I/C Size Up
Built in Suppression
systems
Explosion venting
systems / access
doors
Loading / Unloading
systems
Type & level of
product
Expert advice
18

19. Hopper Fires- Incident Command
I/C Action Plan
Utilize built in
Suppression systems
Activation may trigger
an explosion
No personnel on /near
the hopper when the
suppression system is
activated
Operate system till
fire is extinguished
19

20. Hopper Fires- Incident Command
I/C Action Plan
Access doors - Open
Probability of Dust Explosion
is reduced
Access Doors could be used
to position Aerial Ladder for
low pressure fog stream
Raise Aerial to similar height
and set pump pressure for
low pressure fog stream
Use minimum number of
personnel
20

21. Hopper Fires- Incident Command
I/C Action Plan
Access doors - Closed
Opening Access doors is an
extremely Hazardous
Operation
Limit personnel when
opening access doors or
explosion relief panels
Use least dangerous method
possible ( tie a rope to handle and use elevated
device to unlatch door)
FLOOD HOPPER ( low press fog)
21

22. Hopper Fires- Incident Command
I/C Action Plan
Unloading a Hopper
Unloading kept to a
minimum with light water
fog played on product exit
When hopper gates are
closed wet down the area to
reduce the possibility of dust
in the air
Firefighters should
commence carefully
removing the product from
the area
Repeat until the Hopper is
empty
22

23. Hopper Fires- Incident Command
Safety
If the risk of Explosion is too
great – Defensive position
Maintain an awareness of
the Hopper weight due to
water added during
firefighting operations
Minimize any actions that
disturb the dust in the
Hopper
Treat all Fires in Dust
Collectors / Hoppers as
Potential Severe Explosion
Hazard
23

24. Hopper Fires- Incident Command
Dec 21 2005 Salisbury Maryland
24

25. 25

26. Silo Fires / Explosions
Significant Fires and Explosions.
Alabama
California
Ohio
New York
Nova Scotia – Halifax 2003
Georgia – Imperial Sugar – 13 Killed
Ontario – 2006 Perth, 2008 Woodbridge
26

27. Silo Fires / Explosions
Fire Fighter Serious Injuries / Deaths.
Georgia 1993 – 2 FF killed
Texas 2000 – 1 FF Killed
North Carolina 2001 – 3 FF injured
Nebraska 2002 – 13 FF injured ( shredded
Rubber Silo)
Missouri 2005 – 2 FF killed
Ohio ( Twice) – 1985 & 2003 – 5 FF killed
27

28. Firefighter Injuries / Deaths
August 27th 1985 Marshville Ohio.
Three Firefighters killed, 4 injured.
Concrete Oxygen limiting silo.
50 minutes into fire operations.
10,000 liters of water applied.
SILO EXPLODED
28

29. Firefighter Injuries/ Deaths
October 1st 2003 New Knoxville Ohio.
Two FF’s Killed – 8 injured
Concrete Modified Oxygen Limiting Silo.
2.5 hours into firefighting operations.
30,000 liters applied.
SILO EXPLODED
29

30. Firefighter Injuries / Deaths
December 21st 1997 Iredell
County N.C.
Three Firefighters severely
injured.
Metal Oxygen limiting silo.
2.5 hours into firefighting
operations.
40,000 liters of water applied.
SILO EXPLODED
30

31. Silo Fires / Explosions
Silo Classifications.
Conventional.
Oxygen limiting.
Modified Oxygen
Limiting.
31

32. Conventional Silos
Characteristics.
Most common type.
Reinforced Concrete or
Concrete staves wrapped
in steel bands.
Domed roof ( metal ).
Top unloading.
Unloading chute.
32

33. Conventional Silo
Characteristics.
Most common type.
Reinforced Concrete or
Concrete staves wrapped
in steel bands.
Domed roof ( metal ).
Top unloading.
Unloading chute.
33

34. Conventional Silo
Characteristics.
Most common type.
Reinforced Concrete or
Concrete staves wrapped
in steel bands.
Domed roof ( metal ).
Top unloading.
Unloading chute.
34

35. Oxygen Limiting Silos
Characteristics.
Reinforced concrete,
or metal (blue, green)
Design limits amount
of oxygen in silo.
Flatter roof than a
conventional silo.
No exterior openings
or unloading chutes.
Unloads from the
bottom.
35

36. Oxygen Limiting Silos
Characteristics.
Reinforced concrete,
metal ( blue, green )
Design limits amount of
oxygen in silo.
Flatter roof than a
conventional silo.
No exterior openings or
unloading chutes.
Unloads from the
bottom.
36

37. Oxygen Limiting Silos
Top unloader to
center chute
No exterior
openings or
unloading chutes.
Unloads from the
bottom.
37

38. Oxygen Limiting Silos
Flatter roof.
Venting valves.
Airtight Hatch
Cover.
Hatches will be
sealed with
gaskets / clamps.
38

39. Oxygen Limiting Silo
Satin Finish Flooring
200 Fenmar Dr
39

40. Modified Oxygen Limiting Silo
Modified from Conventional
to Oxygen Limiting
Bottom unloading.
No external chute.
Oxygen Limiting to
Conventional.
Top / bottom unloading.
Top unloading -external
unloading chute and hatches.
Always Treat as
Oxygen Limiting
40

41. Modified Oxygen Limiting Silo
Satin Finish
Flooring
8 Oak St.
41

42. Modified Oxygen Limiting Silo
Satin Finish
Flooring
8 Oak St..
Modified from
Oxygen Limiting
to Conventional
Silo
42

43. Firefighting- Silos
Personal Protection Equipment.
S.C.B.A.: smoke, gasses, oxygen deficiency.
I.M.S.: large hot zone, Safety Officer, R.I.T..
Fall arresting devices: heights.
Confined space: avoid entering.
43

44. Firefighting-Silos
Disconnect power
sources: lock / tag
out.
Protect exposures:
embers, adjacent
buildings.
Extent / location of
fire.
Amount of heat, smoke
and flames.
Thermal imaging
camera.
Drier concrete shades.
44

45. Firefighting-Conventional Silos
Generally slow
burning, deep
seated fires.
Contain the Fire
Usually near the
unloading doors.
Normally within the
top 10 feet of the
silage.
45

46. Firefighting-Conventional Silos
Knock down surface burning
first.
Don’t flood: will not withstand
lateral pressure.
Do not apply water to
exterior of silo.
Minimal chance of structural
collapse from heat
Extinguish pockets with
straight streams, piercing
applicators.
46

47. Firefighting-Conventional Silo
Early stages
Extinguish surface
fire.
Locate hotspots.
Inject water.
directly into hotspot
Open hatches above
to allow for venting.
47

48. Firefighting-Conventional Silos
Advanced Fires.
Leave to burn themselves out.
Product is unsalvageable.
Fires in concrete silos do little harm.
Protect exposures to prevent spread of fire.
Unload silo to ensure complete
extinguishment
48

49. Firefighting-Conventional Silo
Do Not flood the silo.
Water follows path of
least resistance.
Water will run down
the walls, passing
most of the hot
silage.
Inject water directly
into hot spots.
49

50. Firefighting-Oxygen Limiting Silo
Anticipate an
Explosion.
Establish a large
Explosion Zone.
Water supply for a
worst case scenario.
Do nothing to
increase the level of
oxygen in the silo.
DO NOT USE WATER /
FOAM.
50

51. Firefighting-Oxygen Limiting Silo
If Silo is quiet
and no smoke /
steam.
Seal unloading
doors if possible.
close top-hatch.
Do not latch top
hatch cover.
51

52. Firefighting-Oxygen Limiting Silo
May require
injection of Liquid
Nitrogen or Carbon
Dioxide.
(trained professionals).
Seal silo for up to
three weeks.
52

53. Firefighting-Modified Oxygen
Limiting Silo
Always treat a
Modified Oxygen
Limiting Silo as
an Oxygen
Limiting Silo.
53

54. Firefighting- Silos
Pre-plan silos in your Command.
Type, age, and contents.
Fire suppression systems (sprinklers).
Information site personnel, Experts.
Have time to review and confirm pre-plans.
54

55. Silo Gases
Carbon Monoxide (CO).
Carbon Dioxide (CO2).
Nitrogen Dioxide (NO2) – Silo gas.
55

56. Silo Fires / Explosions
It is essential that the incident commander
determines the type of silo, whether the
Silo is a Conventional, Oxygen Limiting, or
modified oxygen limiting.
NEVER proceed with extinguishing
procedures until you are certain the type
of Silo
The contents of a Silo are never worth
putting a firefighter’s life at risk
56