Last data update: May 13, 2024. (Total: 46773 publications since 2009)
Records 1-2 (of 2 Records) |
Query Trace: Soo J-C[original query] |
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Air sampling filtration media: Collection efficiency for respirable size-selective sampling
Soo J-C , Monaghan K , Lee T , Kashon M , Harper M . Aerosol Sci Technol 2015 50 (1) 76-87 The collection efficiencies of commonly used membrane air sampling filters in the ultrafine particle size range were investigated. Mixed cellulose ester (MCE; 0.45, 0.8, 1.2 and 5 microm pore sizes), polycarbonate (0.4, 0.8, 2 and 5 microm pore sizes), polytetrafluoroethylene (PTFE; 0.45, 1, 2 and 5 microm pore sizes), polyvinyl chloride (PVC; 0.8 and 5 microm pore sizes) and silver membrane (0.45, 0.8, 1.2 and 5 microm pore sizes) filters were exposed to polydisperse sodium chloride (NaCl) particles in the size range of 10-400 nm. Test aerosols were nebulized and introduced into a calm air chamber through a diffusion dryer and aerosol neutralizer. The testing filters (37 mm diameter) were mounted in a conductive polypropylene filter-holder (cassette) within a metal testing tube. The experiments were conducted at flow rates between 1.7 and 11.2 l min-1. The particle size distributions of NaCl challenge aerosol were measured upstream and downstream of the test filters by a Scanning Mobility Particle Sizer (SMPS). Three different filters of each type with at least three repetitions for each pore size were tested. In general, the collection efficiency varied with airflow, pore size, and sampling duration. In addition, both collection efficiency and pressure drop increased with decreased pore size and increased sampling flow rate, but they differed among filter types and manufacturer. The present study confirmed that the MCE, PTFE and PVC filters have a relatively high collection efficiency for challenge particles much smaller than their nominal pore size and are considerably more efficient than polycarbonate and silver membrane filters, especially at larger nominal pore sizes. |
Evaluation of pump pulsation in respirable size-selective sampling: Part III. Investigation of European standard methods
Soo J-C , Lee EG , Lee LA , Kashon ML , Harper M . Ann Occup Hyg 2014 58 (8) 1006-17 Lee et al. (Evaluation of pump pulsation in respirable size-selective sampling: part I. Pulsation measurements. Ann Occup Hyg 2014a;58:60–73) introduced an approach to measure pump pulsation (PP) using a real-world sampling train, while the European Standards (EN) (EN 1232-1997 and EN 12919-1999) suggest measuring PP using a resistor in place of the sampler. The goal of this study is to characterize PP according to both EN methods and to determine the relationship of PP between the published method (Lee et al., 2014a) and the EN methods. Additional test parameters were investigated to determine whether the test conditions suggested by the EN methods were appropriate for measuring pulsations. Experiments were conducted using a factorial combination of personal sampling pumps (six medium- and two high-volumetric flow rate pumps), back pressures (six medium- and seven high-flow rate pumps), resistors (two types), tubing lengths between a pump and resistor (60 and 90cm), and different flow rates (2 and 2.5 l min-1 for the medium- and 4.4, 10, and 11.2 l min-1 for the high-flow rate pumps). The selection of sampling pumps and the ranges of back pressure were based on measurements obtained in the previous study (Lee et al., 2014a). Among six medium-flow rate pumps, only the Gilian5000 and the Apex IS conformed to the 10% criterion specified in EN 1232-1997. Although the AirChek XR5000 exceeded the 10% limit, the average PP (10.9%) was close to the criterion. One high-flow rate pump, the Legacy (PP = 8.1%), conformed to the 10% criterion in EN 12919-1999, while the Elite12 did not (PP = 18.3%). Conducting supplemental tests with additional test parameters beyond those used in the two subject EN standards did not strengthen the characterization of PPs. For the selected test conditions, a linear regression model [PPEN = 0.014 + 0.375 × PPNIOSH (adjusted R 2 = 0.871)] was developed to determine the PP relationship between the published method (Lee et al., 2014a) and the EN methods. The 25% PP criterion recommended by Lee et al. (2014a), average value derived from repetitive measurements, corresponds to 11% PPEN. The 10% pass/fail criterion in the EN Standards is not based on extensive laboratory evaluation and would unreasonably exclude at least one pump (i.e. AirChek XR5000 in this study) and, therefore, the more accurate criterion of average 11% from repetitive measurements should be substituted. This study suggests that users can measure PP using either a real-world sampling train or a resistor setup and obtain equivalent findings by applying the model herein derived. The findings of this study will be delivered to the consensus committees to be considered when those standards, including the EN 1232-1997, EN 12919-1999, and ISO 13137-2013, are revised. |
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