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Module 6. Facility Dust Assessment. Terminal Objectives. Upon the successful completion of this module, the participants will be able to describe the benefits of a facility dust assessment. Enabling Objectives. Explain the importance of a facility dust assessment.
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Module 6 Facility Dust Assessment
Terminal Objectives Upon the successful completion of this module, the participants will be able to describe the benefits of a facility dust assessment.
Enabling Objectives • Explain the importance of a facility dust assessment. • Identify the components of a facility dust assessment. • Discuss the value of self-audit checklists.
Facility Dust Assessment • Conducted by a qualified team • Facility Analysis • Hazard Analysis • Consider • Locations where combustible dust is concentrated • Locations where dust can settle • Hidden areas • Occupied areas
Facility Dust Assessment • Identify • Combustible materials • Processes that use/consume/produce combustible dust • Open/hidden areas • Dust dispersion • Potential ignition sources
Facility Dust Assessment • Identify (cont.) • Electrical equipment classification • Ventilation systems • Physical barriers that are present/needed
Dust Combustibility • Primary factor in assessment • MSDS • Do not rely on existing MSDS • Laboratory testing • Determine if specific dust is a hazard • Check concentration levels • Determine MIT cloud
Dust Combustibility-Testing • Godbert-Greenwald Furnace • Air dispersion into furnace • Positive results if flame at bottom of furnace • Increments of 5°C • Standard quality of dust 0.1g • Positive results
Dust Combustibility-Testing • MIT Layer-US Bureau of Mines Test • Metal mesh basket filled with dust • Air of known temperature flowed across powder • Ignition when temperature of powder exceeds air
Dust Combustibility-Testing • Hot Plate Test • Metal ring placed on hot plate • Ring filled with dust • Thermocouples record temperature of hot plate/dust • If dust temperature exceeds hot plate temperature by 20°C then Step 5 • Ignition recorded
Dust Combustibility-Testing • Maximum explosion pressure (Pmax)/Rate of pressure rise (Rmax) • Hartmann apparatus • 20-liter sphere
Dust Characteristics • Dust ignitability/explosibility depends on: • Particle size • Particle shape • Moisture content • Characteristics of dust can change
Hidden Area Inspection • Identify areas where dust accumulates: • Behind equipment • On top of beams • Above suspended ceilings • On top of light fixtures • On platforms
Dispersion Method • Means by which dust may be dispersed • Note • Quantity • Concentration
Ignition Sources • Identify potential ignition sources • Consider process equipment
Electrical Classification • Identify areas requiring classification • CFR 40 §1910.307 • Classification depends on • Flammable properties • Likelihood that flammable/combustible quantity is present
Ventilation System • Key issue when connected to possible stray ignition source • Consider • Fans and blowers • Air separation devices • Ducts • Exhaust air
Physical Barriers • 3 types of barriers • Physical • Mechanical • Chemical • Placed in locations/paths of possible explosion
Checklist “Self-Audit” • Checklists ensures all topics covered • Can use checklists for self audits • Questions to ask • No smoking signs posted? • Equipment free of dust? • Storage tanks equipped with emergency venting?
