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Managing Combustible Dust in Manufacturing - My Experience in Ontario

Managing Combustible Dust in Manufacturing - My Experience in Ontario. Paul Bozek, PEng CIH ROH RT 215 Managing and Regulating Combustible Dust. Outline. Definition of “Combustible” Dusts Typical hazardous processes Typical controls and Issues (examples)

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Managing Combustible Dust in Manufacturing - My Experience in Ontario

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  1. Managing Combustible Dust in Manufacturing - My Experience in Ontario Paul Bozek, PEng CIH ROH RT 215 Managing and Regulating Combustible Dust

  2. Outline • Definition of “Combustible” Dusts • Typical hazardous processes • Typical controls and Issues (examples) • Regulatory Requirements/Guidelines and Programs to manage the risk

  3. Manufacturing Sites Not a comprehensive list, just example industries

  4. Definition of “Combustible Dust” [Pmax x (dP/dt)max]2 Explosion Severity = ------------------------------ (>0.5) [Pmax x (dP/dt)max]1 [MIT x MIE x MEC]1 Ignition Sensitivity = ------------------------------- (>0.2) [MIT x MIE x MEC]2 1 = Pitt Coal 2 = Subject Dust

  5. Definition of “Combustible Dust” • “…..presents risk of fire or deflagration hazard when suspended in air…. • Definition used to include, “<420 microns” • Good Aspects • Not “normally present” suspended in occupied workspaces • Min Explosive Conc. often 1000x OEL

  6. Definition of “Combustible Dust” Problems: (in Hazard Identification) • Parameters are size dependent! • “as is” testing vs “sieve <420 microns” • Full testing is expensive ($3,000+) • Testing for KST alone gives only (dp/dt)max • Moisture content, fat content affect results • MSDS’s often silent or misleading • “as is” product may be too large to be combustible but may contain fines that are combustible

  7. Typical “Settled Dust” Hazards Re-suspended Dust hazard – requires Electrical “Hazardous Location” (Class 2 Division 1 or 2).

  8. “Settled Dust” Hazard Control Positive press? Maintenance Ignition Controls Documented Cleaning Schedule

  9. Typical Hazardous Processes(Explosions Inside Equipment) • Silo and Container Filling • Pneumatic conveying • “Air Material Separators” • Dust Collectors • Cyclones • Size reduction processes (eg grinding) • Sieving, Blending • Drying (eg fluidized bed)

  10. Fireball hazard – Size? Where? Alternately, “suppression” Control: Explosion Venting Vents may be needed in ducts or piping

  11. Dust Collector :Explosion Vent - Locations Vent duct to outdoors “Flameless” Vent

  12. Directly Outside or Inside + secondary filter + “Hazloc” Dust Collector – Air Discharge Location?

  13. Drawing stamped by P.Eng Elec equipment specs meet “Hazloc” classification? Installation inspected by Electrical Authority? Lift trucks rated for Hazloc? Electrical “Hazardous Locations”

  14. Issues: Static Bonding OK?

  15. Issues: Plastic Containers/Liners Size matters – static can build-up on containers or in bulk powders during transfer

  16. Combustible Dust Policy/Programs • Identify, Assess Risk, Control • Recognizing its’ presence historically a problem • Scope of Program Requirements • OH&S Act, Fire Codes, many best practice guides (NFPA) • Change Management • A good time to review compliance/conformance • In Ontario, “Pre-Start H&S Review” requirements have triggered good project-based reviews

  17. Ontario: “Pre-Start H&S Review” Report Requirements • Legally required when new or modified processes • “process involves a risk of ignition or explosion that creates a condition of imminent hazard to a person’s health or safety” • “use of a dust collector involves a risk of ignition or explosion” • Guidelines from Ministry and PEO for P.Eng • Scope of report goes well beyond strict compliance • Includes NFPA 68, 69, 499, 505 & ACGIH Ind Vent.

  18. Thank You! – Acknowledgement: Paul Bozek, PEng CIH ROH p.bozek@utoronto.ca RT 215 Managing and Regulating Combustible Dust

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