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1
Combustible Dust
National Emphasis Program
Ignition Source
March 25, 2010
Ignition Source
Confinement
Oxygen in Air/Oxidizers
Dispersion
Combustible Dust
Deflagration
ExplosionFIRE
2
Overview
• History of Combustible Dust Incidents
• Hazard Mitigation Techniques
• Combustible Dust NEP
3
Catastrophic Combustible Dust Incidents since 1995
4
Malden Mills
Methuen, MA
December 11, 1995
37 Injured
Nylon Fiber
Combustible Dust Explosions History
5
Firefighting efforts following the explosion at Malden Mills (Methuen, Massachusetts, December 11, 1995).
6
Combustible Dust Explosions History
Jahn Foundry
Springfield, MA
February 26, 1999
3 dead9 Injured
Phenolic resin dust
7
Combustible Dust Explosions History
May 16, 2002Rouse PolymericsVicksburg, MS5 dead, 7 injuredRubber Dust
8
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
9
West Pharmaceutical facility destroyed by polyethylene dust
10
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
11
http://www.csb.gov/completed_investigations/docs/CSBFinalReportCTA.pdf
12
Imperial SugarPort Wentworth, Georgia
14Killed
Many Hospitalized
February 7, 2008
Sugar Involved
13
Types of Dust Involved in incidents
Metal20%
Wood24%
Food23%
Other7%
Plastic14%
Coal8%
Inorganic4%
14
Types of Industries Involved in Dust Incidents
Other7%
Food Products24%
Lumber/Wood
Products15%
Chemical Manufact'g.
12%Primary Metal Industries
8%
Rubber & Plastic
Products8%
Electric Services
8%
Furniture & Fixtures
4%Equipment
Manufact'g.7%
Fabricated Metal Products
7%
15
Definitions and Terminology
• Combustible Dust• Combustible Particulate Solid• Hybrid Mixture• Class II Locations• Deflagration• Detonation• Explosion• Minimum Explosible Concentration (MEC)• Lower Flammable Limit (LFL)• Upper Flammable Limit (UFL)• Minimum Ignition Temperature (MIT)• Minimum Ignition Energy (MIE)
16
NFPA 654 (2006) Definitions
Combustible dust. A combustible particulate solid that presents a fire or deflagration hazard when suspended in air or some other oxidizing medium over a range of concentrations, regardless of particle size or shape.
Combustible Particulate Solid. Any combustible solid material composed of distinct particles or pieces, regardless of size, shape, or chemical composition.
Hybrid Mixture. A mixture of a flammable gas with either a combustible dust or a combustible mist.
What is Combustible Dust?
Definitions and Terminology
17
Definitions and Terminology
NFPA 69 (2002), and 499 (2004) Definitions
– Combustible Dust. Any finely divided solid material 420 microns or less in diameter (i.e., material passing through a U.S. No 40 Standard Sieve) that presents a fire or explosion hazard when dispersed
1 micron (µ)
= 1.0 x 10-6 m = 1.0 x 10-4 cm = 1.0 x 10-3 mm
420 µ
= 420 x 10-4 cm = .042 cm
= 0.4mm
A typical paper thickness is approximately 0.1mm
What is Combustible Dust?
18
Standard Sieve Sizes
Sieve Number Sieve opening (µm)
40 425
60 250
80 180
100 150
200 75
230 63
325 45
400 38
19
Particle Size of Common Materials
20
Increase of Surface Area
Surface Area Increases with increasing subdivision
Figures Source: Dust Explosions in the Process Industries, Second Edition, Rolf K Eckhoff
21
Combustion Rate Increase
Combustion Rate Increases with Increasing Subdivision
Slow Combustion Fast Combustion Deflagration/Explosion
Source: Dust Explosions in the Process Industries, Second Edition, Rolf K Eckhoff
22
Deflagration Vs. Explosion
Deflagration. Propagation of a combustion zone at a speed that is less than the speed of sound in the unreacted medium.
Detonation. Propagation of a combustion zone at a velocity that is greater than the speed of sound in the unreacted medium.
Explosion. The bursting or rupture of an enclosure or a container due to the development of internal pressure from deflagration.
Explosion
Deflagration
Detonation
Definitions and Terminology
23 Source: Dust Explosions in the Process Industries, Second Edition, Rolf K Eckhoff
Explosible Range
Dust Deposit
Explosible Range
IH Range
10-3 10-2 10-1 1 10 101 102 103 104 105 106
MASS OF POWDER/DUST PER UNIT VOLUME [g/m3]
24
Dust Fire/Explosion
Combustible Dust Oxygen in Air
Ignition Source
Dispersion Confinement
ExplosionFIRE
Deflagration
25
The “Typical” Explosion Event
ProcessEquipment
InitialInternal Deflagration
Time, msec.0 25 50 75 100 125 150 175 200 225 250 300 325
26
The “Typical” Explosion Event
ProcessEquipment
InitialInternal Deflagration
Shock Wave
Time, msec.0 25 50 75 100 125 150 175 200 225 250 300 325
27
The “Typical” Explosion Event
ProcessEquipment
InitialInternal Deflagration
Elastic ReboundShock Waves
Time, msec.0 25 50 75 100 125 150 175 200 225 250 300 325
28
The “Typical” Explosion Event
Time, msec.0 25 50 75 100 125 150 175 200 225 250 300 325
ProcessEquipment
InitialInternal Deflagration
Dust clouds causedby Elastic Rebound
29
The “Typical” Explosion Event
ProcessEquipment
Containment Failure from InitialDeflagration
Dust Clouds Causedby Elastic Rebound
Time, msec.0 25 50 75 100 125 150 175 200 225 250 300 325
30
The “Typical” Explosion Event
ProcessEquipment
Secondary DeflagrationInitiated
Dust Clouds Causedby Elastic Rebound
Time, msec.0 25 50 75 100 125 150 175 200 225 250 300 325
31
The “Typical” Explosion Event
ProcessEquipment
Secondary DeflagrationPropagates through Interior
Time, msec.0 25 50 75 100 125 150 175 200 225 250 300 325
32
The “Typical” Explosion Event
ProcessEquipment
Secondary DeflagrationVents from Structure
Time, msec.0 25 50 75 100 125 150 175 200 225 250 300 325
33
The “Typical” Explosion Event
Secondary DeflagrationCauses 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.
34
Hazard Mitigation
35
Hazard Mitigation
Dust control
Ignition source control
Explosion Prevention
36
Dust Control
Design of facility & process equipment
Contain combustible dust
Clean fugitive dustRegular program
Access to hidden and overhead areas
Safe cleaning methods
37
Ignition Source Control
Electrical equipment
Static electricity control
Mechanical sparks & friction
Open flame control
Design of heating systems & heated surfaces
Use of tools, & vehicles
38
Explosion Prevention
• Oxidant Concentration Reduction• Deflagration Venting• Deflagration Pressure Containment• Deflagration Suppression Systems• Isolation of equipment
39
OSHA Standards/Citations
Includes:
• Ventilation Standard • Housekeeping Standard. • Housekeeping in storage areas. • Section 5(a)(1) (general duty clause) • Housekeeping violations at coal-handling operations • Personal Protective Equipment (PPE) • Process Safety Management • Electrical • Powered Industrial Trucks • Welding, cutting, and brazing • Warning Signs• Hazard communication • Egress • Fire protection
40
Partial List of Relevant NFPA Standards
NFPANumber
Title
61 Prevention of Fires and Dust Explosions In Agricultural and Food Products Facilities
68 Venting of Deflagrations
69 Explosion Protection Systems
70 National Electrical Code
77 Recommended Practice on Static Electricity
86 Ovens and Furnaces
484 Standard for Combustible Metals, Metal Powders, and Metal Dusts
499 Recommended Practice for the Classification of Combustible Dusts andOf Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas
654 Prevention of Fire and Dust Explosions From the Manufacturing, Processing, And Handling of Combustible Particulate Solids
664 Prevention of Fires and Explosions in Wood Processing and Woodworking Facilities
41
Inspections ConductedInspections Conducted
995
275
0
200
400
600
800
1000
1200
Federal 18(b) State
42
Types of Industries Inspected by Percent
25%
15%
11%10%
10%
7%
6%
4%4%
3% 3%2%
Wood Products
Food Products
Metal Products
Chemical Industries
Rubber/Plastic Prod
Primary Metal
Furniture
Elec/Sanitary Serv.
Transp. Equip
Dur. Goods
Paper Products
Textile mills
43
Industries Inspected under NEP
Types of Industries Inspected
271
157
107 10790
62
37 35 3626
14
010
020
030
0
Woo
dP
rodu
cts
Food
Pro
duct
s
Met
al P
rodu
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Che
mic
alIn
dust
ries
Rub
ber/P
last
icP
rod
Furn
iture
Ele
c/S
anita
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erv.
Mac
hine
s
Dur
. Goo
ds
Pap
erP
rodu
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Text
ile m
ills
Nu
mb
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f In
spec
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ns
44
Total Violations Issued
4,379
1,318
0
500
1000
1500
2000
2500
3000
3500
4000
4500
45
% Inspections In-Compliance(Insps W/O Violations & Closed)
% Inpections in-Compliance
18% 16%
0%
20%
40%
60%
80%
100%
Federal 18(b) State
46
Combustible Dust Related Violations
234
439
151
232
388
88
171
55
193
0
100
200
300
400
500
600
700
5(a
)(1
)
Haz
Co
m
Fir
e E
xtin
gu
ish
ers
Ele
ctri
cal (
Ha
z Lo
c)
Hou
se K
ee
pin
g
Com
pre
sse
d A
ir
PP
E
Fir
st A
id
Pow
ere
d In
du
stri
al T
ruck
s*
*The number of violations pertaining to powered industrial trucks includes those that are combustible dust related (approved for class II locations) and other violations (e.g., training and other items covered under 1910.178).
47
Combustible Dust Related Violations
5(a)(1)12%
HazCom22%
Fire Extinguishers
8%
Electrical (Haz Loc)12%
House Keeping
19%
Compressed Air5%
PPE9%
Powered Industrial Trucks10%
First Aid3%
48
Some Combustible Dust NEP Findings1. Hazardous levels of dust accumulations in the workplaces
due to poor housekeeping practices.
2. Electrical equipment and Powered Industrial Trucks not approved for locations handling combustible dusts
3. Dust collectors were located inside buildings without proper explosion protection systems, such as explosion venting or explosion suppression systems.
4. Deflagration isolation systems were not provided to prevent deflagration propagation from dust handling equipment to other parts of the plant.
5. The rooms with excessive dust accumulations were not equipped with explosion relief venting distributed over the exterior walls and roofs of the buildings.
49
Some Combustible Dust NEP Findings
6. The horizontal surfaces such as beams, ledges and screw conveyors at elevated surfaces were not minimized to prevent accumulation of dust on surfaces.
7. Air from the dust collector was recycled through ductwork back into the work area.
8. Magnetic separators and tramp metal separators were not installed or not functioning to prevent foreign material process stream and potentially cause a spark
9. Explosion vents on bucket elevatior(s) and dust collectors were directed into work areas and not vented to a safe, outside location away from platforms, means of egress, or other potentially occupied areas
50
Some Combustible Dust NEP Findings
10. Equipment (such as grinders and shakers) were not maintained to minimize escape of dust into the surrounding work area.
11. Ductworks used in transporting combustible dust were not constructed of metal (conductive) and were not bonded or grounded to minimize generation and accumulation of static electricity.
12. Hot work (open flame or sparks from welding, cutting, grinding) was performed in the combustible dust handling areas without hot work procedures.
51
Oct 1, 2007 – March 22, 2010SIC 3089
Data Criteria SIC 3089
Total number of Inspections 64
Total Violations Issued 249
Avg. Number of Violations Issued Per Initial Inspection 5.1
Percent Total Violations Cited As Serious 66%
Avg. Current Penalty Per Serious Violation $946
52
1910.1200 Hazard Communications -- 22 Violations
1910.147 Lockout/Tagout -- 20 Violations
1910.212 Machine Guarding – 20 Violations
1910.022 Housekeeping – 16 Violations
1910.134 Respiratory Protection -- 16
1910.305 Electrical (Wiring Methods, Components and Equipment) -- 13
1910.217 Mechanical Power Presses -- 12
5(a)(1) General Duty Clause – 11 Violations
1910.132 Personal Protective Equipment -- 11
1910.219 Mechanical Power Transmission -- 10
OSHA Standards Violated at Facilities with SIC 3089
53
OSHA Training
• Over 350 compliance officers trained on PSM with combustible dust being a component
• 200 compliance officers have received specific combustible dust training
• Approximately 1400 state and federal compliance officers received webinar refresher training
54
OSHA Compliance Assistance Resources: Combustible Dust
• Safety and Health Topics Page
• Fact Sheet
• Poster
• Safety and Health Information Bulletin (2005)
OSHA’s Combustible Dust Poster
55
Combustible Dusts Regulations Status?
56
Questions?
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