Parallel Particle Impactors New Personal Samplers for Accurate - PowerPoint PPT Presentation

Parallel Particle Impactors – New Personal Samplers for Accurate Assessment of Worker Exposure to Respirable or Thoracic Dust Saulius Trakumas, Peter M. Hall, and Donald L. Smith SKC Inc., Eighty Four, Pennsylvania www.skcinc.com

� Sampler should approximate particle penetration through human respiratory tract when purpose of monitoring workers exposure to airborne particulates is health- related.

ACGIH, CEN, and ISO have defined sampling conventions for size-selective sampling of airborne health-related particles: � Inhalable (particles that enter nose/mouth) � Thoracic (fraction of particles that penetrates down to the larynx) � Respirable (fraction of particles that penetrates down to the alveolar region of the lungs)

Size-selective Sampling Conventions for Health-related Airborne Particulates 100 Sampling Efficiency, E, % 75 Inhalable 50 25 Respirable Thoracic 0 1 10 100 Aerodynamic Particle Diameter, d a , µ m

Size-selective Particle Samplers � Cyclone

Performance of Six Respirable Cyclones GS-1 Dorr-Oliver GS-3 100 100 100 GS-1 Cyclone, Q S =2.0 L/min GS-3 Cyclone, Q S =2.75 L/min Dorr-Oliver Cyclone, Q S =1.7 L/min Test Aerosol: Test Aerosol: Test Aerosol: Sampling Efficiency, E, % Sampling Efficiency, E, % Sampling Efficiency, E, % DOP DOP DOP 75 75 75 Glass Spheres Glass Spheres Glass Spheres Coal Mine Dust Coal Mine Dust Coal Mine Dust 50 50 50 25 25 25 Respirable Convention Respirable Convention Respirable Convention 0 0 0 0 2 4 6 8 10 0 2 4 6 8 10 0 2 4 6 8 10 Aerodynamic Particle Diameter, d a , µ m Aerodynamic Particle Diameter, d a , µ m Aerodynamic Particle Diameter, d a , µ m Aluminum BGI-4CP SIMPED 100 100 100 BGI-4CP Cyclone, Q S =2.2 L/min Aluminum Cyclone, Q S =2.5 L/min SIMPED Cyclone, Q S =2.2 L/min Test Aerosol: Test Aerosol: Test Aerosol: Sampling Efficiency, E, % Sampling Efficiency, E, % Sampling Efficiency, E, % 75 DOP DOP DOP 75 75 Glass Spheres Glass Spheres Glass Spheres Coal Mine Dust Coal Mine Dust Coal Mine Dust 50 50 50 25 25 25 Respirable Convention Respirable Convention Respirable Convention 0 0 0 0 2 4 6 8 10 0 2 4 6 8 10 0 2 4 6 8 10 Aerodynamic Particle Diameter, d a , µ m Aerodynamic Particle Diameter, d a , µ m Aerodynamic Particle Diameter, d a , µ m

Size-selective Particle Samplers � Cyclone � Foam

Size-selective Particle Samplers � Cyclone � Foam � Horizontal elutriator

Size-selective Particle Samplers � Cyclone � Foam � Horizontal elutriator � Conventional impactor

Simulation of Respirable Curve Using Impactors 100 Six impactors: d 50 =7.1, 5.4, 4.4, 3.7, 3.0, and 1.8 µ m 75 Four impactors: d 50 =6.6, 4.6, 3.5, and 2.2 µ m Penetration, P, % Two impactors: d 50 =5.6, and 2.9 µ m 50 25 Respirable Convention Single Impactor: d 50 =4.0 µ m 0 0 2 4 6 8 10 Aerodynamic Particle Diameter, d a , µ m

V. Marple’s design of multiple-nozzle, single- stage impactor* µ ρ 9 WSt WV = = 50 0 D Re ρ µ 50 W 2 50 W 1 CV p 0 1 ∆ = ρ P V 0 2 Q s =2.0 Lpm D 50 , µ m D 50 , µ m D 50 , µ m d in , mm d in , mm No. of nozzles No. of nozzles d in , mm No. of nozzles 6.4 5.0 2.3 2.5 1 1 5.8 2.4 1 4.2 2.5 0.63 1.0 16 5 3.5 0.87 8 3.0 2.2 0.48 0.33 23 53 2.1 0.22 109 * Virgil A. Marple. 1978. Simulation of Respirable Penetration Characteristics by Inertial Impaction. J. Aerosol Sci., Vol.9, pp.125-134.

Parallel Particle Impactor (PPI) W 1in W 2in W 1out W 2out 1 ∆ = ∆ + ∆ ∆ = ρ P P P P V 0 i iIn iOut 2 1 1 1 1 1 1 ρ + ρ = ρ + ρ = = ρ + ρ 2 2 2 2 2 2 V V V V ..... V V 1 In 1 Out 2 In 2 Out NIn NOut 2 2 2 2 2 2 ⎛ ⎞ ⎛ ⎞ ⎛ ⎞ 1 1 1 1 1 1 ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ + = + = = + 2 2 2 Q Q ..... Q ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ 1 2 N 2 2 2 2 2 2 ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ S S S S S S 1 In 1 Out 2 In 2 Out NIn NOut *US Patent pending

Parallel Particle Impactor Prototype Respirable PPI (Q s =2.0 Lpm) D 50 , µ m d in , mm d out , mm 6.6 2.59 1.30 4.6 2.06 1.33 3.5 1.73 1.40 2.2 1.30 2.59 Thoracic PPI (Q s =2.0 Lpm) D 50 , µ m d in , mm d out , mm 17.5 5.10 2.12 11.9 4.00 2.18 8.9 3.25 2.25 4.8 2.12 5.10

Aerosol Experimental Generator Clean Air Setup (50 Lpm) Charge Neutralizer Virtual Impactor Turbulence Clear Plexiglass Generators Cylinder Test aerosol used: (D=12 , H=48 ) ” ” � DOP Honeycomb � PST Flow Straightener � Glass Spheres Test � Coal Mine Dust Device Access Port Sampling ( ) C d Lines = × Down E ( d ) 100 % Foam C ( d ) To Filter Up Makeup Flow Ball Valve Aerodynamic Particle Sizer (APS 3320)

� APS was calibrated periodically using PSL particles of known size � To minimize erroneous counts and coincidence effect, small test particles were removed before entering test chamber using a virtual impactor and test particle concentration inside the chamber was kept below 100 cm -3 .

Experimental Setup

Performance of Individual Impactors of Respirable PPI Prototype 100 Impactor 50% cut-off, d 50 , µ m No Design Measured 1 6.6 6.4 2 4.6 4.7 75 3 3.5 3.6 Penetration, P, % 4 2.2 2.3 50 25 Q S =0.5 L/min PST test particles 0 0 2 4 6 8 10 12 Aerodynamic Particle Diameter, d a , µ m

Overall Performance of Respirable PPI Prototype 100 Respirable Convention Curve constructed using experimental data obtained for each individual impactor 75 Performance of whole sampler Performance of sampler exposed to coal mine Penetration, P, % dust for 6 hours (~ 4.5 mg/m 3 ) 50 Q S =2.0 L/min PST test particles 25 0 0 2 4 6 8 10 12 Aerodynamic Particle Diameter, d a , µ m

Performance of Respirable PPI Prototype when Tested Using Different Test Particles 100 Test Particles: PST ( ρ p =1.79 g/cc) 75 Glass Spheres ( ρ p =2.5 g/cc) Penetration, P, % DOP ( ρ p =0.99 g/cc) 50 25 Respirable Convention 0 0 2 4 6 8 10 12 Aerodynamic Particle Diameter, d a , µ m

Comparison of Performance of Respirable PPI Prototype and HD Cyclone 100 75 Penetration, P, % 50 PPI, Q S =2.0 L/min 25 Respirable Convention HD Cyclone, Q S =2.2 L/min 0 0 2 4 6 8 10 12 Aerodynamic Particle Diameter, d a , µ m

Bias Maps of Respirable PPI Prototype and HD Cyclone <-10% -10%< <-5% -5%< <5% 5%< <10% >10% Geometric Standard Deviation, GSD 3.5 3.0 Respirable PPI prototype 2.5 2.0 1.5 3.5 3.0 HD Cyclone 2.5 2.0 1.5 1 3 5 7 9 11 13 15 17 19 21 23 25 Mass Median Diameter, MMAD, µ m

Parallel Particle Impactor Final Design Inlet Impaction Plate Exhaust

Performance of Respirable and Thoracic PPIs 100 75 Penetration, P, % Respirable 50 Thoracic PPI Convention 25 Thoracic Convention Respirable PPI 0 0.5 1 5 10 50 Aerodynamic Particle Diameter, d a , µ m

Conclusion � A novel design incorporating several inertial impactors arranged in parallel was applied to fabricate respirable and thoracic PPIs. � PPIs were found to follow accurately appropriate conventions. PPI samplers performed equally well for liquid and solid test particles and penetration characteristics remained unchanged after prolonged exposure to coal mine dust.

Conclusion � The suggested PPI design can be applied to model a sampler with characteristics simulating the shape of any monotonically changing predetermined curve at a selected flow rate.