Download - Dr Fiona Clarkson - Simtars
Becoming aware of the risk factors associated with your particular dusts
Dr Fiona Clarkson
Simtars
How and why dust composition varies
1. Origin of the parent product
Liquid, bulk product, grain, milled product
2. End use of the product
Powder, blended product
End use determines how a product is handled in a
process system.
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What you need to understand about your dust and its characteristics
Dust can be a combustible dust hazard as either a dust cloud, a dust layer or both
• Particle size
• Particle shape
• Moisture content
• Density
• Origin - plant, animal, mineral or man made
The limitation of relying on material data sheets
• Not all products have an SDS.
Chemicals require an SDS
Exemptions – some food products
– some pharmaceuticals
• The SDS may not list all the components
Slide 4
The limitation of relying on material data sheets
Review the Physical and Chemical Properties Section
Slide 5
The limitation of relying on material data sheets
The SDS is only as good as the information supplied by the manufacturer
Slide 6
The limitation of relying on material data sheets
• Key information may be spread over several sections
Slide 7
What is dust testing and how is it done ?
Series of internationally recognised tests to
evaluate the physical properties of fine powders
Explosion testing in the Siwek 20 litre sphere
Explosibility – Siwek sphere
Concentration range of 30g/m3 to 2000g/m3
Slide 9
Explosion Characteristics Max. explosion pressure: Pmax = .0 bar ± 10%
Max. rate of pressure rise: (dP/dt)max = 0 bar / s ± 30%
Product specific constant: Kmax = 0 m·bar / s ± 30%
Explosibility – Siwek sphere
Slide 10
Explosion Characteristics
Max. explosion pressure: Pmax = 8.6 bar ± 10% Max. rate of pressure rise: (dP/dt)max = 901 bar / s ± 10% Product specific constant: Kmax = 245 m·bar / s ± 10%
Explosion Indices – Siwek sphere
Slide 11
Explosion Characteristics
Max. explosion pressure: Pmax = 8.6 bar ± 10% Max. rate of pressure rise: (dP/dt)max = 912 bar / s ± 10% Product specific constant: Kmax = 247 m·bar / s ± 10%
Minimum Explosive Concentration / Lower Explosive Limit
Slide 12
Minimum Ignition Energy - MIKE 3
Spark with inductance
Spark with no inductance
Energy Levels 1000 mJ
300 mJ
100 mJ
30 mJ
10 mJ
3 mJ
1 mJ
Slide 13
Minimum Ignition Energy - MIKE 3
Slide 14
Minimum Ignition Energy
Result with inductance L = 1 mH
1 mJ < MIE < 3 mJ / Es = 1.6 mJ
E2 [mJ]: 3 3 3 3 3 Es [mJ]: 2.6 2.0 2.3 1.6 1.9 E1 [mJ]: 1 1 1 1 1
tv [ms]: 60 90 120 150 180
Minimum Ignition Temperature - Cloud
Slide 15
Vertical Plate
600°C to 200°C
Flame = Ignition
3 to 5 seconds
Minimum Ignition Temperature - Layer
Slide 16
Horizontal Plate
450°C to 100°C
Embers / Ash
= Ignition
Minimum Ignition Temperature - Layer
Slide 17
Isolated Embers
Whole sample
30 to 90 minutes
per test
Potential Testing Reports – Explosion Testing
Slide 18
Simtars - Combustible Dust Laboratory
Sample: R2060033/01 CaRo2015 Customer: Simtars Reason: CaRo2015 Sphere Verification Testing Data to sample origin: Ex Kuhner Preparation of sample: As Supplied Median value: As Supplied
Explosion Characteristics
Max. explosion pressure: Pmax = 8.6 bar ± 10% Max. rate of pressure rise: (dP/dt)max = 912 bar / s ± 10% Product specific constant: Kmax = 247 m·bar / s ± 10%
Potential Testing Reports –Minimum Ignition Energy Testing
Slide 19
Potential Testing Reports –Minimum Ignition Temperature Testing
Slide 20
Potential Testing Reports – Particle Size Analysis
Slide 21
Risk considerations of unknown dust particles
Particle size
• Is the median particle size in the millimetre, micron or nano particle range ?
Concentration in the atmosphere
• Can I see a dust cloud ?
• Can I see through it ?
Unknown Chemical Composition
• Could the dust be a skin sensitizer if handled or toxic if inhaled ?
Slide 22
Risk considerations of unknown dust particles
Is the material likely to have come from a plant, animal, mineral / metal refining or man made source ?
Decomposition products
• Could the off gases be toxic ?
Ignition sources
• Are there any potential ignition sources nearby eg Hot work, ovens / furnaces, motors or large electrical power sources
Slide 23