Field Testing of New Aerosol Sampling Method With a Porous Curved Surface as Inlet

Hauck, Brian C.; Grinshpun, Sergey A.; Reponen, Auvo; Reponen, Tiina; Willeke, Klaus; Bornschein, Robert L.

doi:10.1080/15428119791012351

Cited by 29 publications

(15 citation statements)

References 16 publications

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“…These performance features were attributed to the curved shape of its porous inlet. A field evaluation confirmed its low dependence on wind velocity and direction, its good collection uniformity, and its low intersample variation (Hauck et al, 1997).…”

Section: Introductionmentioning

confidence: 87%

Airflow and Particle Velocities Near a Personal Aerosol Sampler with a Curved, Porous Aerosol Sampling Surface

Aizenberg

Bidinger

Grinshpun

et al. 1998

Aerosol Science and Technology

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ABSTRACT. The airflow and particle-velocity patterns in the vicinity of a curved, porous sampling surface constituting the inlet of an aerosol sampler, have been determined by Laser-Doppler Velocimetry. The tests were performed on a personal aerosol sampler with a concave sampling surface, referred to a s the "button" sampler. Measurements with the button sampler were conducted in a low-speed, open-circuit, horizontal wind tunnel using two types of monodisperse aerosols: 2 p m essentially inertialess propylene glycol particles (their trajectories represent the flow streamlines) and 44 p m inertial fly ash particles. The tests were performed a t two free stream velocities (0.5 and 4 mis) and two sampler orientations (facing the wind and facing downward a t 90' to the wind). The sampling flow rate was 2 Limin. Sampling through the curved surface was conducted while the button sampler was freely suspended in the flow or while it was attached to a vertical stagnation plate simulating the human torso. The results indicated that the nondimensionalized airflow patterns and particle-velocity fields near the curved inlet surface were similar a t different wind velocities, a s long as the button sampler faced the wind. When a stagnation plate was added, while facing the wind, the airflow patterns and particle trajectories were not significantly affected. Based on limiting streamline considerations, it was concluded that only a small part of the incoming flow was aspired into the inlet. This limited transparency of the inlet to the incoming airflow caused the deflection of the airflow along the curved surface and explained the low dependence of the airflow patterns on the magnitude of the free stream velocity when the curved inlet surface faced the wind. However, the effects of wind velocity and plate on the airflow and particle velocity became significant when the inlet orientation was changed to 90" to the wind. This suggests that a curved, porous surface is beneficial as a n aerosol sampling inlet when the wind direction is perpendicular or close to perpendicular to the surface. However, this benefit is reduced or eliminated when sampling a t 90' to the wind.

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Section: Introductionmentioning

confidence: 87%

Airflow and Particle Velocities Near a Personal Aerosol Sampler with a Curved, Porous Aerosol Sampling Surface

Aizenberg

Bidinger

Grinshpun

et al. 1998

Aerosol Science and Technology

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“…1B). The Button aerosol sampler is designed to operate at 4 liters/min so that its inlet aspiration efficiency follows the inhalable sampling convention (39), but it has been used with flow rates as high as 10 liters/min (40), and the use of a 7.5-liter/min flow rate instead of the nominal 4 liters/min allowed us to collect more bacteria in a short time. The effect of sampling time on cell membrane integrity was investigated by using two different sampling protocols: (i) sampling of aerosolized E. coli for 5 min and (ii) sampling of aerosolized E. coli for 5 min followed by the passing of particle-free air though the filter for 2 h. Once the sampling was completed, the filter was removed from the sampler and placed into a 10-ml Tween mixture solution containing 0.1% peptone (Fisher, Fair Lawn, NJ), 0.01% Tween 80 (Fisher, Fair Lawn, NJ), and 0.005% Y-30 antifoam reagent (Sigma, St. Louis, MO) (18).…”

Section: Methodsmentioning

confidence: 99%

Release of Free DNA by Membrane-Impaired Bacterial Aerosols Due to Aerosolization and Air Sampling

Zhen

Han

Fennell

et al. 2013

Appl Environ Microbiol

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We report here that stress experienced by bacteria due to aerosolization and air sampling can result in severe membrane impairment, leading to the release of DNA as free molecules. Escherichia coli and Bacillus atrophaeus bacteria were aerosolized and then either collected directly into liquid or collected using other collection media and then transferred into liquid. The amount of DNA released was quantified as the cell membrane damage index (I D )

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“…Nonuniformity of lter deposition for this sampler was found to be less than half that for the closed-face 25 mm lter cassette when facing the wind. The uniformity for a 45 ± yaw angle was also superior (Kalatoor et al 1995;Hauck et al 1997). Air ow and particle velocity patterns in the vicinity of the sampler have also been determined using laser-doppler velocimetry (LDV) in a wind tunnel (Aizenberg et al 1998).…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, other design parameters of the simulated rst prototype button sampler might need to be adjusted in order to follow the inhalable convention more closely. The button sampler demonstrated good lter collection uniformity, but particle deposition was concentrated near the center of the lter when using a standard closed-face cassette (Hauck et al 1997). Figure 7 shows a typical particle path plot for particles (d a D 50 ¹m) that were released upstream at a wind velocity of 2.0 m/s.…”

Section: Particle Trajectories and Particle-wall Interactionmentioning

confidence: 99%

A Numerical Study of the Performance of an Aerosol Sampler with a Curved, Blunt, Multi-Orificed Inlet

Gao

Chen

Baron

et al. 2002

Aerosol Science and Technology

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The purpose of this study was to numerically simulate the performance of an aerosol sampler with a curved, blunt, multi-ori ced inlet in order to understand the sampling characteristics of the rst prototype of the button personal inhalable aerosol sampler ("button sampler"). Because the button sampler inlet design is too complicated to apply a three-dimensional model, an axisymmetric two-dimensional model was created to be similar in geometry and to simulate the major features of the air ow through the sampler when facing the wind. Particle trajectories were calculated in a variety of wind velocities and were categorized into 5 groups based on their interactions with the curved surface of the sampling plane.Empirical sampling ef ciencies of the button sampler for 3 particle sizes were used to adjust the calculated sampling ef ciencies in an attempt to improve the accuracy of the two-dimensional axisymmetric model in accounting for interactions between particles and the surface of the inlet of the button sampler. Sampling ef ciencies for other particle sizes were then predicted. The results showed that sampling ef ciency decreased with increasing particle size up to approximately 40 ¹m and then remained virtually unchanged at about 35% up to 100 ¹m. Although the ef ciencies were lower than the American Conference of Governmental Industrial Hygienists' (ACGIH) inhalability curve for larger particles, the pattern of the predicted sampling ef ciency was quite similar to the ACGIH inhalability curve. Sampling ef ciencies for liquid aerosol particles larger than 15 ¹m were predicted to be noticeably lower than those for solid particles.The results also showed that the multi-ori ced curved surface played an important role in establishing a pressure drop with desired ow alignment inside the sampler, thus greatly reducing the The authors would like to express their appreciation to Drs. Klaus Willeke and Sergey Grinshpun of the University of Cincinnati for providing experimental data that was used for comparison to our numerical results and for valuable discussions; to Dr. Vladimir Hnizdo at the National Institute for Occupational Safety and Health for his help on tting the numerical data to the experimental results; and to Drs. Matthew Godo and Ashwini Kumar of FLUENT Inc. for support with FIDAP software applications.Address correspondence to Pengfei Gao, National Institute for Occupational Safety and Health, P.O. Box 18070, Cochrans Mill Road, Pittsburgh, PA 15236. E-mail: pgao@cdc.gov wind effect and signi cantly improving the uniformity of particle deposition on the lter. The less uniform deposition found at high wind velocity can be improved by increasing the sampling ow rate.

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Field Testing of New Aerosol Sampling Method With a Porous Curved Surface as Inlet

Cited by 29 publications

References 16 publications

Airflow and Particle Velocities Near a Personal Aerosol Sampler with a Curved, Porous Aerosol Sampling Surface

Airflow and Particle Velocities Near a Personal Aerosol Sampler with a Curved, Porous Aerosol Sampling Surface

Release of Free DNA by Membrane-Impaired Bacterial Aerosols Due to Aerosolization and Air Sampling

A Numerical Study of the Performance of an Aerosol Sampler with a Curved, Blunt, Multi-Orificed Inlet

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