1 Module 6 Facility Dust Assessment

2 Terminal Objectives Upon the successful completion of this module, the participants will be able to describe the benefits of a facility dust assessment.

3 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.

4 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

5 Facility Dust Assessment Identify –Combustible materials –Processes that use/consume/produce combustible dust –Open/hidden areas –Dust dispersion –Potential ignition sources

6 Facility Dust Assessment Identify (cont.) –Electrical equipment classification –Ventilation systems –Physical barriers that are present/needed

7 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

8 Dust Combustibility-Testing Godbert-Greenwald Furnace 1.Air dispersion into furnace 2.Positive results if flame at bottom of furnace 3.Increments of 5°C 4.Standard quality of dust 0.1g 5.Positive results

9 Dust Combustibility-Testing MIT Layer-US Bureau of Mines Test 1.Metal mesh basket filled with dust 2.Air of known temperature flowed across powder 3.Ignition when temperature of powder exceeds air

10 Dust Combustibility-Testing Hot Plate Test 1.Metal ring placed on hot plate 2.Ring filled with dust 3.Thermocouples record temperature of hot plate/dust 4.If dust temperature exceeds hot plate temperature by 20°C then Step 5 5.Ignition recorded

11 Dust Combustibility-Testing Maximum explosion pressure (Pmax)/Rate of pressure rise (Rmax) –Hartmann apparatus –20-liter sphere

12 Dust Characteristics Dust ignitability/explosibility depends on: –Particle size –Particle shape –Moisture content Characteristics of dust can change

13 Hidden Area Inspection Identify areas where dust accumulates: –Behind equipment –On top of beams –Above suspended ceilings –On top of light fixtures –On platforms

14 Dispersion Method Means by which dust may be dispersed Note –Quantity –Concentration

15 Ignition Sources Identify potential ignition sources Consider process equipment

16 Electrical Classification Identify areas requiring classification CFR 40 § Classification depends on –Flammable properties –Likelihood that flammable/combustible quantity is present

17 Ventilation System Key issue when connected to possible stray ignition source Consider –Fans and blowers –Air separation devices –Ducts –Exhaust air

18 Physical Barriers 3 types of barriers –Physical –Mechanical –Chemical Placed in locations/paths of possible explosion

19 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?

20 MESHsystems Online Audit System