Grain Handling – Dust Explosion Hazards

1. Grain Handling – DustExplosionHazards Paul Schlumper Georgia Tech Research Institute 404-407-6797

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

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

4. Dust explosions An initial (primary) explosionin • processing equipment or in an areawhere 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 causeone or more secondary explosions. • These can befar more destructivethan a primary explosion

5. 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.

6. 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.

7. Facility Analysis Components 29 CFR 1910 Identify and follow the applicablefederal, state, and local lawsand regulations.Some commonly applicable mandatory requirements • OSHA General Duty Clause and Standards • The International Code Council’s International Fire Code® • NFPA’s Uniform Fire Code®. OSHA • Local building codes frequently adopt NFPA dust standards by reference

8. 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

9. Dust Combustibility Combustible dust per NFPA 654 • Prior to 2006 - “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. Agricultural Dust per NFPA 61 • Any finely divided solid agricultural material 420 microns or smaller in diameter that presents a fire or explosion hazard when dispersed and ignited in air.”

10. 2 meters OSHA 40 g/m3 concentration of comb. dust suspended in air 25 watts Glass Glass Dust Combustibility *25 watt light bulbprobably can not be seen through ten feet of a combustible dust mixture What bulb?

11. What is wrong here?

12. Electrical classification Electrical Equipment Class II Division 1 Division 2 Group E F G • OSHAElectrical 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.

13. 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.” NOTE: 1910.272 stipulates 1/8 inch for Grain Dust

14. Dust Control Spots are not raindrops NFPA 654 - 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;

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

16. Class II Div 1 Group EFG HAZ LOC HAZ LOC 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;

17. Classified Electrical

18. Ignition Control 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! Yes!

19. 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

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

21. Ignition Control Other ignition sources Use appropriate Class II Electrical equipment and wiring methods where required OSHA 29 CFR 1910.178 (c) regulates powered industrial trucks in dust areas Coal handling operations must comply with OSHA 29 CFR 1910.269 Class I & II Group D & G

22. 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

23. List of Chemicals 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.

24. NFPA Standards – Dust Hazards • 61 Standard for the Prevention of Fires and Dust Explosions in Agricultural and Food Processing Facilities • 68 Deflagration Venting Systems • 69 Explosion Prevention Systems • 70 National Electric Code • 77 Static Electricity • 85 Boiler and CombustionSystems • 86 Ovens and Furnaces • 91 Exhaust Systems

25. NFPA StandardsElectrical & 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

26. 1910.272 – Grain Handling Facilities(Promulgated in March 1988) (i) – Contractors (j) – Housekeeping (k) – Grate Openings (l) – Filter Collectors (m) – Preventive Maintenance (n) - Grain Stream Processing Equipment (o) – Emergency Escape (p) – Continuous-Flow Bulk Raw Grain Dryers (q) – Inside Bucket Elevators • (a) – Scope • (b) – Application • (c) – Definitions • (d) – Emergency Action Plan • (e) – Training • (f) – Hot Work Permit • (g) – Entry Into Grain Storage Structures • (h) – Entry Into Flat Storage Structures

27. Application of Standard • Sections (a) – (n) • Apply to all grain handling operations, such as elevators, mills, etc. • Sections (o) – (q) • Apply to grain elevator operations only.

28. Hot Work Permit • Hot Work Permits • Written • Authorized by Employer’s Representative • Meet requirements of 1910.252(a) • Kept on file until completion of operations • Exceptions • Authorizing agent is present • Authorized welding shop • Authorized hot work area – outside of grain facility

29. Contractor Information • Fire Hazards • Explosion Hazards • Safety Rules of the Facility • Emergency Action Plan

30. Housekeeping • Housekeeping Program • Written • Establish Frequency and Methods to Reduce Accumulations: • Ledges • Floors • Equipment • Other Exposed Surfaces • Priority Housekeeping Areas, including at least the following: • Floor areas within 35 feet (10.7 m) of inside bucket elevators; • Floors of enclosed areas containing grinding equipment; • Floors of enclosed areas containing grain dryers located inside the facility. • Important: Fugitive grain dust accumulations exceeding 1/8 inch shall be removed immediately from priority housekeeping areas.

31. Housekeeping

32. Housekeeping • Compressed Air can be used for cleaning IF: • Machinery in area shut-down • All other potential ignition sources shut-down and/or removed.

33. Housekeeping

34. Housekeeping

35. Dust Collection Systems • Fabric Dust Filter Collectors • Pressure drop monitoring device • Located outside of facility, OR • Protected by an Explosion Suppression System, OR • Protected by Fire-Resistant Construction

36. Preventive Maintenance • Equipment: • Dryers • Grain Stream Processing Equip. • Dust Collection Equipment • Bucket Elevators • Preventative Maintenance • Regularly scheduled inspections • Mechanical • Safety Control Equipment • 1910.272(m)(1) The employer shall implement preventive maintenance procedures consisting of: • Lubrication and other appropriate maintenance • Prompt correction of: • Malfunctioning dust collection systems • Inside bucket elevator failures: • Overheated bearings and/or slipping/misaligned belts • Certified Inspection Record • LOTO

37. Grain Stream Processing Equipment • Grain stream processing equipment shall be equipped with an effective means of removing ferrous material from the incoming grain stream.

38. Continuous-Flow Bulk Raw Grain Dryers • All direct-heat grain dryers shall be equipped with automatic controls that: • Will shut-off the fuel supply in case of power or flame failure or interruption of air movement through the exhaust fan; and, • Will stop the grain from being fed into the dryer if excessive temperature occurs in the exhaust of the drying section. • Direct-heat grain dryers installed after March 30, 1988 shall be: • Located outside the grain elevator; or • Located in an area inside the grain elevator protected by a fire or explosion suppression system; or • Located in an area inside the grain elevator which is separated from other areas of the facility by construction having at least a one hour fire-resistance rating

39. Inside Bucket Elevators • Bucket elevators shall not be jogged to free a choked leg. • Belts and lagging shall be conductive • < 300 Megaohms electrical resistance rating • Bucket elevators shall have a means of access to: • Head pulley area • Boot area

40. Inside Bucket Elevators • Bearing are to be mounted external to leg casing • Bearing monitoring device is required • Belt monitoring • Motion detection device – to indicate choking condition • Belt alignment device

41. Hazard Monitoring Devices • Sample Motion Probe Located on Tail Shaft of Bucket Elevator

42. Hazard Monitoring Devices • Bearing Temperature Monitoring • Sample Display • Internal Hot Bearing Sensor Installed Through Grease Fitting

43. Hazard Monitoring Devices • Belt Alignment Monitoring

44. NFPA 61 – Standard for the Prevention of Fires and Dust Explosions in Agricultural and Food Processing Facilities • 1-Administration • 2-Referenced Publications • 3-Definitions • 4-Construction Requirements • 5-Ventilation and Venting • 6-Explosion Prevention, Relief, and Venting • 7-Equipment • 8-Dryers • 9-Heat Transfer Operations • 10-Dust Control • 11-Pneumatic Conveying • 12-Building Fire Protection • 13-Supplemental Requirements

45. QUESTIONS?