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

Aerodynamic Particle Diameter, da, µm 1 10 100 Sampling Efficiency, E, % 25 50 75 100

Inhalable Thoracic Respirable

Size-selective Particle Samplers

Cyclone

Performance of Six Respirable Cyclones

Aluminum

Aerodynamic Particle Diameter, da, µm 2 4 6 8 10 Sampling Efficiency, E, % 25 50 75 100

Respirable Convention

Dorr-Oliver Cyclone, QS=1.7 L/min Test Aerosol:

DOP Glass Spheres Coal Mine Dust

Dorr-Oliver

Aerodynamic Particle Diameter, da, µm 2 4 6 8 10 Sampling Efficiency, E, % 25 50 75 100

Respirable Convention

GS-1 Cyclone, QS=2.0 L/min Test Aerosol:

DOP Glass Spheres Coal Mine Dust

GS-1 GS-3

Aerodynamic Particle Diameter, da, µm 2 4 6 8 10 Sampling Efficiency, E, % 25 50 75 100

Respirable Convention

SIMPED Cyclone, QS=2.2 L/min Test Aerosol:

DOP Glass Spheres Coal Mine Dust

BGI-4CP

Aerodynamic Particle Diameter, da, µm 2 4 6 8 10 Sampling Efficiency, E, % 25 50 75 100

Respirable Convention

BGI-4CP Cyclone, QS=2.2 L/min Test Aerosol:

DOP Glass Spheres Coal Mine Dust

SIMPED

Aerodynamic Particle Diameter, da, µm 2 4 6 8 10 Sampling Efficiency, E, % 25 50 75 100

Respirable Convention

GS-3 Cyclone, QS=2.75 L/min Test Aerosol:

DOP Glass Spheres Coal Mine Dust

Aerodynamic Particle Diameter, da, µm 2 4 6 8 10 Sampling Efficiency, E, % 25 50 75 100

Respirable Convention

Aluminum Cyclone, QS=2.5 L/min Test Aerosol:

DOP Glass Spheres Coal Mine Dust

Size-selective Particle Samplers

Cyclone Foam

Size-selective Particle Samplers

Cyclone Foam Horizontal elutriator

Size-selective Particle Samplers

Cyclone Foam Horizontal elutriator Conventional impactor

Aerodynamic Particle Diameter, da, µm 2 4 6 8 10 Penetration, P, % 25 50 75 100

Respirable Convention Single Impactor: d50=4.0 µm Two impactors: d50=5.6, and 2.9 µm Four impactors: d50=6.6, 4.6, 3.5, and 2.2 µm Six impactors: d50=7.1, 5.4, 4.4, 3.7, 3.0, and 1.8 µm

Simulation of Respirable Curve Using Impactors

• V. Marple’s design of multiple-nozzle, single-

stage impactor*

2 1 V P ρ = ∆

50 50

9 CV WSt D

p

ρ µ = µ ρ

50

WV Re = W1 W2

* Virgil A. Marple. 1978. Simulation of Respirable Penetration Characteristics by Inertial Impaction.

• J. Aerosol Sci., Vol.9, pp.125-134.

8 0.87 3.5 53 0.33 2.2 1 2.4 5.8

• No. of nozzles

din, mm D50,µm 16 0.63 2.5 1 2.5 5.0

• No. of nozzles

din, mm D50,µm 23 0.48 3.0 5 1.0 4.2 109 0.22 2.1 1 2.3 6.4

• No. of nozzles

din, mm D50,µm Qs=2.0 Lpm

Parallel Particle Impactor (PPI)

2 1 V P ρ = ∆

iOut iIn i

P P P ∆ + ∆ = ∆

2 2 2 2 2 2 2 1 2 1

2 1 2 1 ..... 2 1 2 1 2 1 2 1

NOut NIn Out In Out In

V V V V V V ρ ρ ρ ρ ρ ρ + = = + = +

⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + = = ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + = ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ +

2 2 2 2 2 2 2 2 2 2 1 2 1 2 1

1 1 ..... 1 1 1 1

NOut NIn N Out In Out In

S S Q S S Q S S Q

W1in W2in

*US Patent pending

W1out W2out

Parallel Particle Impactor Prototype

1.33 2.06 4.6 2.59 1.30 2.2 1.40 1.73 3.5 1.30 2.59 6.6 dout, mm din, mm D50,µm

Respirable PPI (Qs=2.0 Lpm)

2.18 4.00 11.9 5.10 2.12 4.8 2.25 3.25 8.9 2.12 5.10 17.5 dout, mm din, mm D50,µm

Thoracic PPI (Qs=2.0 Lpm)

Experimental Setup

% 100 ) ( ) ( ) ( × = d C d C d E

Up Down

Test aerosol used:

DOP PST Glass Spheres Coal Mine Dust

Clean Air (50 Lpm) Virtual Impactor Charge Neutralizer Turbulence Generators Honeycomb Flow Straightener Clear Plexiglass Cylinder (D=12 , H=48 ) ” ” Access Port Foam Sampling Lines Ball Valve Test Device To Filter Makeup Flow Aerosol Generator 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

Aerodynamic Particle Diameter, da, µm 2 4 6 8 10 12 Penetration, P, % 25 50 75 100

QS=0.5 L/min PST test particles Impactor 50% cut-off, d50, µm No Design Measured 1 6.6 6.4 2 4.6 4.7 3 3.5 3.6 4 2.2 2.3

Performance of Individual Impactors of Respirable PPI Prototype

Overall Performance of Respirable PPI Prototype

Aerodynamic Particle Diameter, da, µm 2 4 6 8 10 12 Penetration, P, % 25 50 75 100

QS=2.0 L/min PST test particles Curve constructed using experimental data obtained for each individual impactor Performance of whole sampler Respirable Convention Performance of sampler exposed to coal mine dust for 6 hours (~ 4.5 mg/m3)

Aerodynamic Particle Diameter, da, µm 2 4 6 8 10 12 Penetration, P, % 25 50 75 100

Test Particles: PST (ρp=1.79 g/cc) DOP (ρp=0.99 g/cc) Glass Spheres (ρp=2.5 g/cc) Respirable Convention

Performance of Respirable PPI Prototype when Tested Using Different Test Particles

Aerodynamic Particle Diameter, da, µm 2 4 6 8 10 12 Penetration, P, % 25 50 75 100

HD Cyclone, QS=2.2 L/min Respirable Convention PPI, QS=2.0 L/min

Comparison of Performance of Respirable PPI Prototype and HD Cyclone

Bias Maps of Respirable PPI Prototype and HD Cyclone

1.5 2.0 2.5 3.0 3.5 1 3 5 7 9 11 13 15 17 19 21 23 25

Geometric Standard Deviation, GSD Mass Median Diameter, MMAD, µm

1.5 2.0 2.5 3.0 3.5

<-10% -10%< <-5% -5%< <5% 5%< <10% >10%

Respirable PPI prototype HD Cyclone

Inlet Exhaust Impaction Plate

Parallel Particle Impactor Final Design

Performance of Respirable and Thoracic PPIs

Aerodynamic Particle Diameter, da, µm Penetration, P, %

25 50 75 100

Respirable PPI Thoracic PPI Thoracic Convention Respirable Convention

0.5 1 5 10 50

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

• f any monotonically changing predetermined curve

at a selected flow rate.