Aerosol Sampling Efficiency of 37 mm Filter Cassettes

Buchan, Roy M.; Soderholm, Sidney C.; Tillery, M.I.

doi:10.1202/0002-8894(1986)047<0825:aseomf>2.3.co;2

Cited by 23 publications

(27 citation statements)

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“…While 100% sampling efficiency may be the goal for many stationary samplers, personal aerosol sampling almost always requires a sizeselective approach, since it collects the particle fraction seen by a specific portion of the human respiratory tract (inhalable, thoracic, or respirable fraction). It is well recognized that sampling in the presence of a large (human) body may change substantially the flow pattern around the sampler, which results in a change of its overall aerosol sampling cfficiency (Buchan et al, 1986). The human body creates an air stagnation zone in front of the sampler when sampling while facing the wind, and a zone of turbulence around it when sampling at an angle to the flow.…”

Section: Introductionmentioning

confidence: 99%

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: 99%

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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show abstract

“…Similar comparison studies also indicate that the actual ratios depend on the size of the particles that are generated, with higher ratios measured for activities that generate coarse particles versus activities that generate fine particles (de Vocht et al, 2006;Kenny et al, 1997;Kerr et al, 2002;and Tatum et al, 2001). Various wood dust studies have shown the CFC to under-sample particles in the inhalable range from 0 -100 m (Buchan et al, 1986;Lee et al, 2011;Martin and Zalk, 1998;Tatum et al, 2001). Some field comparisons for the IOM and 37 mm samplers (open and closed face) have shown the IOM sampler to collect around 2-3 times more mass than the 37-mm samplers, whereas laboratory comparisons have shown a factor of 1.2 -1.4 (Kenny et al, 1997).…”

Section: Background and Significancementioning

confidence: 76%

A Comparison of "Total Dust" and Inhalable Personal Sampling for Beryllium Exposure

Carter

2012

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“…Problems associated with the 37 mm closed-faced cassettes include leakage around the filter due to the assembly process, non-uniform sample deposition on the filter, and electrostatic charges from the plastic materials (Baron 1998, Baron et al 2002. It is estimated that open-faced 37 mm cassettes collect one to three times more aerosol sample than a closed-face cassette (Buchan et al 1986). Both open-and closed-face cassettes can have isoaxial flow problems with collection efficiency from airflow direction across the top of the inlet similar to other collection devices.…”

Section: Filtrationmentioning

confidence: 99%