1. Combustible Dust Hazards and Controls Paul Schlumper
Georgia Tech Research Institute

2. “Combustible Dust in Industry:
Adapted from
“Combustible Dust in Industry:
Preventing and mitigating the effects of fires and explosions”
OSHA Safety and Health Information Bulletin
Acknowledgement – Ben Ross – OSHA Region IV
Deadly dust

3. This presentation describes:
Hazards of combustible dust
Work practices
Guidelines
Training to protect employees
OSHA’s National Emphasis Program
Potential Citations

4. Background Organic Dust Fires and Explosions: North Carolina
(6 killed, 38 injured)
Kentucky
(7 killed, 37 injured

5. Organic Dust Fire and Explosion: North Carolina
Combustible polyethylene dust accumulated above suspended ceilings at pharmaceutical plant
A fire at the plant caused dust to be dispersed and explode in the ceiling space
6 were killed, 38 injured
Plant and nearby buildings were severely damaged

6. Organic Dust Fire and Explosion: Kentucky
A fire at an unattended oven ignited a dust cloud created by cleaning operations at a facility making fiberglass insulation for the automotive industry.
The explosion was fueled by resin dust accumulated in a production area,
The resin involved was a phenolic binder used in producing fiberglass mats.

7. Dust Explosion Requirements
Fuel
Ignition
Dispersion
Confinement
Adapted from CSB
Oxygen

8. Dust explosion in a work area
Dust settles on flat surfaces
Some event disturbs the settled dust into a cloud
Dust cloud is ignited and explodes
Adapted from CSB

9. Dust explosions An initial (primary) explosion in
processing equipment or in an area where fugitive dust has accumulated
may shake loose more accumulated dust, or
damage a containment system (such as a duct, vessel, or collector).
The additional dust dispersed into the air may cause one or more secondary explosions.
These can be far more destructive than a primary explosion

10. Facility Dust Hazard Assessment
Combustible dust explosion hazard may exist in a variety of industries
food (e.g., candy, starch, flour, feed),
plastics,
wood,
rubber,
furniture,
textiles,
pesticides,
pharmaceuticals,
dyes,
coal,
metals (e.g., aluminum, chromium, iron, magnesium, and zinc), and
fossil fuel power generation.

11. Particles and Powders*
Size
Pellets > 2mm diameter
Granules 0.42mm and 2mm, and
dust particles < 0.42mm (420μm)
Hazard increases as particle size decreases
larger surface area for combustion
Fine particle may have a larger role in dust cloud ignition and explosion propagation.

12. Particles and Powders*
Dusts may occur in the process stream and cause a hazard, regardless of starting particle size of the material
may break
into
This or

13. Facility Analysis Components
Carefully identify:
Materials that can be combustible when finely divided;
Processes which use, consume, or produce combustible dusts;
Open areas where combustible dusts may build up;
Hidden areas where combustible dusts may accumulate;
Means by which dust may be dispersed in the air; and
Potential ignition sources.

14. Dust Combustibility
See Explosives regulations
The primary factor in an assessment of these hazards is whether the dust is in fact combustible.
*Determine if a dust cloud will:
Detonate
Deflagrate
Present a fire hazard
Or will Not burn or ignite
Testing may be necessary

15. Dust Combustibility Combustible dust per NFPA 654
Prior to “Any finely divided solid material that is 420 microns or smaller in diameter (material passing a U.S. No. 40 Standard Sieve) and presents a fire or explosion hazard when dispersed and ignited in air.”
*2006 Edition – 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.

16. Dust Combustibility Violence
*OSHA work site health Limits (PELs) 2.5 ug/m3 ( g/m3) through 15 mg/m3 (.015 g/m3)
Explosive range for combustible dusts 15 g/m3 through (Approx.) 1200 g/m3
Violence
g/m3
Dust cloud concentration

17. comb. dust suspended in air
Dust Combustibility
*25 watt light bulb probably can not be seen through ten feet of a combustible dust mixture
What bulb?
25 watts
2 meters
Glass
OSHA
40 g/m3 concentration of
comb. dust suspended in air

18. What is wrong here?

19. Dust Combustibility Information sources (some better than others)
“As used” test data
Chemical supplier test data
MSDS sheets
Published tables
Variables
Particle size,
Shape
Moisture content.
Changes in the material produced by process equipment.
Many others

20. Electrical classification
OSHA Electrical standard (29 CFR Part 1910 Subpart S)
NFPA 70, the National Electrical Code®.
NFPA 499, Classification of Combustible Dusts and of Hazardous (classified) Locations for Electrical Installations in Chemical Process Areas.
Electrical
Equipment
Class II
Division 1
Division 2
Group A B C

21. Other Hazard Analysis Considerations
Some subjective (and not always accurate) rules of thumb
*Begin cleaning when dust reaches
When you can write in it
When it obscures the color of the surface
1/64th inch thick
1/32nd inch thick
1/16th inch thick
1/8th inch thick
Really no need to clean - if it hasn’t exploded by now, it won’t

22. CPL 03-00-008 – National Emphasis Program
“immediate cleaning is warranted whenever a dust layer of 1/32-
inch thickness accumulates over a surface area of at least 5% of
the floor area of the facility or any given room. The 5% factor
should not be used if the floor area exceeds 20,000 ft2, in which
case a 1,000 ft2 layer of dust is the upper limit. Accumulations
on overhead beams, joists, ducts, the tops of equipment, and
other surfaces should be included when determining the dust
coverage area. Even vertical surfaces should be included if the
dust is adhering to them. Rough calculations show that the
available surface area of bar joists is approximately 5 % of the
floor area and the equivalent surface area for steel beams can be
as high as 10%.”

23. Dust Control Some of its recommendations:
Spots are not raindrops
NFPA contains comprehensive guidance
Some of its recommendations:
Minimize the escape of dust from process equipment or ventilation systems;
Use dust collection systems and filters;
Utilize surfaces that minimize dust accumulation and facilitate cleaning;

24. Dust Control ? NFPA 654 – guidance
Deadly Dust ?
NFPA 654 – guidance
Provide access to all hidden areas to permit inspection;
Inspect for dust residues in open and hidden areas, at regular intervals;
Clean dust residues at regular intervals;

25. Dust Control NFPA 654 – guidance
Use cleaning methods that do not generate dust clouds, if ignition sources are present;
Only use vacuum cleaners approved for dust collection;
Class II
Div 1
Group EFG
HAZ LOC
HAZ LOC

26. Ignition Control No! NFPA 77
NFPA 654, identifies comprehensive guidance
Use appropriate electrical equipment and wiring methods;
Control static electricity, including bonding of equipment to ground;
Control smoking, open flames, sparks;
No!
NFPA 77

27. Ignition Control NFPA 654 - guidance
Control mechanical sparks and friction;
Use separator devices to remove foreign materials capable of igniting combustibles from process materials;
Separate heated surfaces from dusts;
Non - Magnetic
rotating drum
Magnetic
Core

28. Ignition Control NFPA 654 - guidance
Hot work
permit
_________
NFPA guidance
Separate heating systems from dusts;
Proper use and type of industrial trucks;
Proper use of cartridge activated tools; and
Adequately maintain equipment.
Kaboom!
Grinder

29. Ignition Control Other ignition sources
Use appropriate Class II Electrical equipment and wiring methods where required
OSHA 29 CFR (c) regulates powered industrial trucks in dust areas
Coal handling operations must comply with OSHA 29 CFR
Class I & II
Group D & G

30. Training Employees need to be trained
To recognize and prevent hazards associated with combustible dust
In taking preventative action, and/or
How to alert management.
Hazardous vertical surface accumulation

31. Training They need to know
The safe work practices applicable to their job tasks,
The overall plant programs for dust control and ignition source control.
Training must be
Before they start work
Periodically to refresh their knowledge
When reassigned
When hazards or processes change

32. Training Management Responsibility
Comply with the Hazard Communication Standard
Have a qualified team conduct a facility analysis (or have one done by qualified outside persons) prior to the introduction of a hazard and
Develop a prevention and protection scheme tailored to the operation.
List of Chemicals

33. Training
Supervisors and managers should be aware of and support the plant dust and ignition control programs.
Their training should include identifying how they can encourage the reporting of unsafe practices and facilitate abatement actions.

34. NEP/ Industry Application
Food products
Agriculture
Chemicals
Textiles
Forest and furniture products
Metal processing
Tire and rubber manufacturing plants
Paper products
Pharmaceuticals
Wastewater treatment
Recycling operations (metal, paper, and plastic)
Coal dust in coal handling and processing facilities

35. Primary Applicable OSHA Standards
General – Housekeeping
Hazardous (Classified) Locations
Powered Industrial Trucks
Bakery Equipment
Sawmills
Grain Handling
General Duty Clause
General and industry-specific

36. NFPA Standards – Dust Hazards
61 Agriculture
68 Deflagration Venting Systems
69 Explosion Prevention Systems
70 National Electric Code
77 Static Electricity
85 Boiler and Combustion Systems
86 Ovens and Furnaces
91 Exhaust Systems

37. NFPA Standards Electrical & Systems
484 Combustible Metals
Includes Magnesium, Titanium, Zirconium, Aluminum, Tantalum and other reactive metals
499 Classification of Combustible Dust
654 manufacturing, Processing and Handling of Combustible Particulate Solids
655 Sulfur
664 Wood
and more

38. Database of Combustible Dust
BGIA GESTIS-DUST-EX Database of Combustion and Explosion Characteristics of Dusts
Important characteristics of more than 4000 dust samples from virtually all sectors of industry
Developed in Germany with the financial support of the EC

39. Database of Combustible Dust
There are limits of applicability of the data
a wide variation is possible in the nature of the dusts
e.g., composition, particle size distribution, surface structure, moisture content, etc.
the numerical value of the characteristics depend on the test methods
Always be aware that the values listed only serve as a guideline for the design of preventive and protective measures.

40. Citations Typical hazards
Accumulation of combustible dust in areas which have/may have ignition sources
Lack of, or inadequate, explosion mitigation
Failure to control ignition sources inside equipment
Cleaning dust with non-explosion proof equipment (e.g., vacuums)

41. Citations Typical hazards (con’t) PPE Inadequate Ventilation
Cleaning dust with compressed air (electrostatic issue)
PPE
Inadequate Ventilation
HazCom training

42. Citations Cite the HAZARD!!!
Where possible, use OSHA/State OSHA standards
(a)(1) – General Housekeeping
(c) – Housekeeping in storage areas
(See Class II Locations)
Class III and Class I Locations may be an issue, too
(v)(11)(xii) – Electrical Power Generation
State specific standards

43. Citations 5(a)(1) See the Sample Citations File
NFPA standards are used as both
Evidence of industry recognition
Feasible and Acceptable Abate method
Reference Mandatory “shalls” in NFPA to ensure standard requirements
Use “shoulds” for abatement recommendations

44. Citations Other important standards 1910.1200 – HazCom 1910.132(a)
Failure to train
Inadequate MSDS
Also a possible source of employer knowledge
(a)
Properly assess workplace hazards & provide
Non-static clothing
Flame retardant clothing
Footwear

45. Citations Other important standards 1910.119
When dust is listed in Appendix A, can be cited in its entirety
Possible citations if dust explosion hazard not evaluated in Process Hazard Analysis and could affect covered processes
May lead to additional citations such as:
Siting
Training
Operating procedures, etc.

46. Citations Other important standards
(Powered Industrial Trucks)
(Welding, Cutting and Brazing)
(c)(3) – Warning signs
(or )
(k)(2) – Bakery Equipment
(c)(20)(i) – Sawmills
Agriculture
HazCom
General Duty

47. © J Howicz 2008

48. © J Howicz 2008

49. © J Howicz 2008

50. © J Howicz 2008

51. © J Howicz 2008

52. PROPOSED VIOLATIONS Egregious willful: 8 Willful violations:
12 instances of housekeeping by location ( (a)(1) & (a)(2))
44 instances of electrical equipment not classified for area ( (c)(1)(i))
5 instances of powered industrial trucks not classified for the area ( (c)(2)(vii))
8 Willful violations:
Explosion prevention systems (5a1)
Dust collection deficiencies (5a1)
Operation of “sweeper” in hazardous locations (5a1)
Fall Protection ( & 23)
Unguarded belt & pulley ( (d)(1) & (e)(3)(i)

53. PROPOSED VIOLATIONS 51 Serious violations
Dust collection system installed improperly (5a1)
Masonry construction of exterior wall in powder room (5a1)
Conveyor belts with no sensors (5a1);
Maintenance of boilers (5a1)
Stairs & Ladders
Egress
Manlifts
Fire extinguishers
Machine Guarding
Welding
Electrical
Lead
Maritime

54. TOTAL PENALTIES $5,062,000 Egregious: $4,270,000 Willful: $560,000
Serious: $232,000

55. QUESTIONS?