Comment on Comparison of Powder Dustiness Methods

doi:10.1093/annhyg/met086

Cited by 3 publications

(1 citation statement)

References 6 publications

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“…Aerosolization proceeds under turbulent conditions, whereas in the gentle tests, the airflows are larger scale and laminar. The reproducibility [59] of the method has been criticized [63] but has been defended [64]. The method involves more aggressive air flows than those typically encountered in large-scale workplace activities (however, the use of compressed air to clean contaminated worker clothing or work surfaces approximates the aerodynamic conditions of the VDT).…”

Section: Introductionmentioning

confidence: 99%

Computational fluid dynamics analysis of the Venturi Dustiness Tester

2017

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Dustiness quantifies the propensity of a finely divided solid to be aerosolized by a prescribed mechanical stimulus. Dustiness is relevant wherever powders are mixed, transferred or handled, and is important in the control of hazardous exposures and the prevention of dust explosions and product loss. Limited quantities of active pharmaceutical powders available for testing led to the development (at University of North Carolina) of a Venturi-driven dustiness tester. The powder is turbulently injected at high speed (Re ~ 2 × 104) into a glass chamber; the aerosol is then gently sampled (Re ~ 2 × 103) through two filters located at the top of the chamber; the dustiness index is the ratio of sampled to injected mass of powder. Injection is activated by suction at an Extraction Port at the top of the chamber; loss of powder during injection compromises the sampled dustiness. The present work analyzes the flow inside the Venturi Dustiness Tester, using an Unsteady Reynolds-Averaged Navier-Stokes formulation with the k-ω Shear Stress Transport turbulence model. The simulation considers single-phase flow, valid for small particles (Stokes number Stk <1). Results show that ~ 24% of fluid-tracers escape the tester before the Sampling Phase begins. Dispersion of the powder during the Injection Phase results in a uniform aerosol inside the tester, even for inhomogeneous injections, satisfying a necessary condition for the accurate evaluation of dustiness. Simulations are also performed under the conditions of reduced Extraction-Port flow; results confirm the importance of high Extraction-Port flow rate (standard operation) for uniform distribution of fluid tracers. Simulations are also performed under the conditions of delayed powder injection; results show that a uniform aerosol is still achieved provided 0.5 s elapses between powder injection and sampling.

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Section: Introductionmentioning

confidence: 99%

Computational fluid dynamics analysis of the Venturi Dustiness Tester

2017

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Evaluation of total and inhalable samplers for the collection of carbon nanotube and carbon nanofiber aerosols

Dahm

Evans

Bertke

et al. 2019

Aerosol Science and Technology

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A growing number of carbon nanotubes and nanofibers (CNT/F) exposure and epidemiologic studies have utilized 25-and 37-mm open-faced cassettes (OFCs) to assess the inhalable aerosol fraction. It has been previously established that the 37-mm OFC undersamples particles >20 mm in diameter, but the size-selective characteristics of the 25-mm OFC have not yet been fully evaluated. This article describes an experimental study conducted to determine if the 25-and 37-mm OFCs performed with relative equivalence to a reference inhalable aerosol sampler when challenged with CNT/F particles. Side-by-side paired samples were collected within a small Venturi chamber using a 25-mm styrene OFC, 37-mm styrene OFC, 25-mm aluminum OFC, and button inhalable aerosol sampler. Three types of CNT/F materials and an Arizona road dust were used as challenge aerosols for the various sampler configurations. Repeated experiments were conducted for each sampler configuration and material. The OFC samplers operated at flow rates of 2 and 5 L/min. Results showed that the 25-mm OFC performed comparably to the button sampler when challenged with CNT/F aerosols, which was demonstrated in five of the six experimental scenarios with an average error of 21%. Overall, the results of this study indicate that the sampling efficiency of the 25-and 37-mm OFCs adequately followed the ISO/ACGIH/CEN inhalable sampling convention when challenged with CNT/F aerosols. Past exposure and epidemiologic studies that used these OFC samplers can directly compare their results to studies that have used other validated inhalable aerosol samplers.

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Numerical Investigation of Aerosolization in the Venturi Dustiness Tester: Aerodynamics of a Particle on a Hill

Palakurthi

Ghia

Turkevich

2022

Journal of Fluids Engineering

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Understanding particle detachment from surfaces is necessary to better characterize dust generation and entrainment. Previous work has studied the detachment of particles from flat surfaces. The present work generalizes this to investigate the aerodynamics of a particle attached to various locations on a model hill. The present work serves as a model for dust aerosolization in a tube, as powder is injected into the Venturi Dustiness Tester. The particle is represented as a sphere in a parallel plate channel, or, in two dimensions, a cylinder oriented perpendicular to the flow. The substrate is modified to include a conical hill (3d) or wedge (2d), and the test particle is located at various positions on this hill. The governing incompressible Navier-Stokes equations are solved using the finite-volume FLUENT code. The coefficients of lift and drag are compared with the results on the flat substrate. Enhanced drag and significantly enhanced lift are observed as the test particle is situated near the summit of the hill.

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Comment on Comparison of Powder Dustiness Methods

Cited by 3 publications

References 6 publications

Computational fluid dynamics analysis of the Venturi Dustiness Tester

Computational fluid dynamics analysis of the Venturi Dustiness Tester

Evaluation of total and inhalable samplers for the collection of carbon nanotube and carbon nanofiber aerosols

Numerical Investigation of Aerosolization in the Venturi Dustiness Tester: Aerodynamics of a Particle on a Hill

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