The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform

Virgil A. Marple - One of the best experts on this subject based on the ideXlab platform.

  • design and evaluation of a low flow personal Cascade Impactor
    Aerosol Science and Technology, 2018
    Co-Authors: Modi Chen, Francisco J Romay, Virgil A. Marple
    Abstract:

    ABSTRACTA very compact Cascade Impactor with 2 L/min sampling flow rate has been developed. Its dimensions are 8.5 cm L x 5.0 cm W x 11.4 cm H, and it weighs 0.27 kg, with ten impaction stages with aerodynamic cutpoints in the range of 60 nm to 9.6 μm. The top eight stages, collecting particles down to 170 nm in aerodynamic diameter, can be used as a stand-alone Impactor with a portable, battery-powered pump. Particle collection efficiencies were obtained with two types of commonly used substrates, aluminum foil and glass fiber filters. Impactor cutpoints with aluminum foil substrates agree well with conventional Impactor theory. The efficiency curves are sharp with minimum overlap between them. Thus, the compact Impactor design does not compromise its performance, making it suitable for general purpose applications where a lower sampling flow rate provides adequate mass collection. With glass fiber filter substrates, Impactor cutpoints are smaller and the efficiency curves are less steep, in particular f...

  • a novel quartz crystal Cascade Impactor for real time aerosol mass distribution measurement
    Aerosol Science and Technology, 2016
    Co-Authors: Modi Chen, Francisco J Romay, Amir Naqwi, Virgil A. Marple
    Abstract:

    ABSTRACTA quartz crystal microbalance (QCM) based instrument has been developed for real-time aerosol mass distribution measurement. It includes two key components: a six-stage QCM micro-orifice Cascade Impactor and a novel relative humidity (RH) conditioner. This instrument operates at a flow rate of 10 L·min−1 and measures the mass of the collected particles in six aerodynamic diameter channels between 45 nm and 2.5 μm. The RH conditioner ensures that the aerosol particles are collected at an RH between 40% and 65%, which is critical for eliminating particle bounce and for ensuring optimal particle coupling with the QCM. The nozzles of the Impactors are clustered in the center of the nozzle plates. Therefore, particles are deposited on the central electrode of the QCM, where the mass calculated from first principles (i.e., Sauerbrey equation) agrees with the actual collected mass. The QCM response is linear up to around 130 μg for solid particles and up to around 2 μg for liquid particles. The collectio...

  • rapid check of Cascade Impactor cut sizes using a polydisperse challenge aerosol calibration method
    Aerosol Science and Technology, 2006
    Co-Authors: Virgil A. Marple, Bernard A. Olson, Kumaragovindhan Santhanakrishnan
    Abstract:

    A method has been developed to check the 50% cut-size values of Cascade Impactor stages. The method involves generating a broad-size, log-normally distributed aerosol that covers the range of 50% cut-sizes for the Impactor being tested. The amount of deposit on each impaction plate is analyzed and a histogram of the resulting aerosol size distribution plotted, using the amount of aerosol collected on each impaction plate and the published values for the cut-sizes of the Impactor in question. If the particle size distribution indicated by the histogram does not result in a log-normal distribution, one or more of the assumed cut-sizes of the Impactor are in error. The incorrect cut-sizes of the Impactor can then be adjusted until the curve is log-normal, and these adjusted cut-sizes are the correct values for the Impactor stages.

  • A Low-Loss Cascade Impactor with Stage Collection Cups: Calibration and Pharmaceutical Inhaler Applications
    Aerosol Science and Technology, 1995
    Co-Authors: Virgil A. Marple, Bernard A. Olson, Nicholas C. Miller
    Abstract:

    A new Cascade Impactor design having low interstage losses is described. A novel feature is the use of external stage collection cups, to simplify applications requiring chemical determination of the mass collected on each stage. The design has been executed in versions to operate at two flow rates: 30 and 60 L/min. Calibration data are presented for these flow rates, and, in addition, for the latter version at 90 L/min. Size results using the new Impactor on a typical pharmaceutical inhalation product are shown to be equivalent to those obtained using a current Cascade Impactor. An example is presented to indicate the utility of gathering size data at more than one flow rate.

Constantinos Sioutas - One of the best experts on this subject based on the ideXlab platform.

  • Field evaluation of a personal Cascade Impactor sampler (PCIS)
    Atmospheric Environment, 2003
    Co-Authors: Manisha Singh, Chandan Misra, Constantinos Sioutas
    Abstract:

    Abstract This paper presents the field evaluation of a personal Cascade Impactor sampler (PCIS). PCIS is a miniaturized Cascade Impactor, consisting of four impaction stages, followed by an after-filter. Particles are separated in the following aerodynamic particle diameter ranges: 2 O (2.7 kPa). For field evaluation, the PCIS was collocated with other samplers including the micro-orifice uniform deposit Impactor (MOUDI), scanning mobility particle sizer (SMPS) and aerodynamic particle sizer (APS) in Los Angeles and Claremont, CA. PCIS and MOUDI agree very well for coarse particulate matter (PM) (PM 2.5−10 ) mass concentrations. The fine PM (PM 2.5 ) mass as measured by PCIS is in excellent agreement with SMPS–APS measurement (∼1.02 times) and slightly higher (∼1.1 times) than the MOUDI measurements. Time-integrated (size fractionated) PM 2.5 mass, inorganic ions (nitrate and sulfate), elemental carbon (EC) and organic carbon (OC) concentrations obtained with PCIS and MOUDI were found to be in very good agreement with few differences in the 2.5 nitrate and total carbon measurements by PCIS and MOUDI using the ADI and Sunset labs monitors are in close agreement for all size fractions, indicating that any differences between MOUDI and PCIS measurements for time-integrated data might be due to artifacts associated with long-term sampling and not to differences in individual cut-points. The performance of the PCIS was also evaluated in wind tunnel tests at wind speeds up to 8 km/h. These tests showed that particle sampling efficiency and separation characteristics of the PCIS are unaffected by the wind speeds for particles up to 10 μm in aerodynamic diameter.

  • development and evaluation of a personal Cascade Impactor sampler pcis
    Journal of Aerosol Science, 2002
    Co-Authors: Chandan Misra, Manisha Singh, Si Shen, Constantinos Sioutas, Peter M Hall
    Abstract:

    This paper presents development and evaluation of a personal sampler for particulate matter that allows separation of airborne particles by size. The Personal Cascade Impactor Sampler (PCIS) is a miniaturized Cascade Impactor, consisting of four impaction stages, followed by an after-filter. Particles are separated in the following aerodynamic particle diameter ranges: <0.25, 0.25–0.5, 0.5–1.0, 1.0–2.5 and 2.5–. The PCIS operates at a flow rate of using a very high efficiency, battery-operated light pump at a pressure drop of 11 in H2O (). PTFE (Teflon), quartz and aluminum substrates were chosen for characterization of the PCIS. Laboratory tests conducted with monodisperse polystyrene latex (PSL) particles as well as polydisperse ammonium sulfate and ammonium nitrate aerosols corroborated the cutpoints. Our experimental characterization identified Teflon filters as ideal impaction substrates because they result in high collection efficiency of particles above the cutpoint of each stage without the use of adhesive coatings, do not collect excessively particles below the cutpoint (a problem encountered with the use of quartz substrates) and because of their ability to be used for gravimetric analysis. Particle loading tests indicated that the PCIS stages could collect up to 3.16 and of fine and coarse PM, respectively, without any loss in the collection efficiency, which would have been a result of particle bounce.

  • Development and evaluation of a personal Cascade Impactor sampler (PCIS)
    Journal of Aerosol Science, 2002
    Co-Authors: Chandan Misra, Manisha Singh, Si Shen, Constantinos Sioutas, Peter M Hall
    Abstract:

    This paper presents development and evaluation of a personal sampler for particulate matter that allows separation of airborne particles by size. The Personal Cascade Impactor Sampler (PCIS) is a miniaturized Cascade Impactor, consisting of four impaction stages, followed by an after-filter. Particles are separated in the following aerodynamic particle diameter ranges:

Peter M Hall - One of the best experts on this subject based on the ideXlab platform.

  • development and evaluation of a personal Cascade Impactor sampler pcis
    Journal of Aerosol Science, 2002
    Co-Authors: Chandan Misra, Manisha Singh, Si Shen, Constantinos Sioutas, Peter M Hall
    Abstract:

    This paper presents development and evaluation of a personal sampler for particulate matter that allows separation of airborne particles by size. The Personal Cascade Impactor Sampler (PCIS) is a miniaturized Cascade Impactor, consisting of four impaction stages, followed by an after-filter. Particles are separated in the following aerodynamic particle diameter ranges: <0.25, 0.25–0.5, 0.5–1.0, 1.0–2.5 and 2.5–. The PCIS operates at a flow rate of using a very high efficiency, battery-operated light pump at a pressure drop of 11 in H2O (). PTFE (Teflon), quartz and aluminum substrates were chosen for characterization of the PCIS. Laboratory tests conducted with monodisperse polystyrene latex (PSL) particles as well as polydisperse ammonium sulfate and ammonium nitrate aerosols corroborated the cutpoints. Our experimental characterization identified Teflon filters as ideal impaction substrates because they result in high collection efficiency of particles above the cutpoint of each stage without the use of adhesive coatings, do not collect excessively particles below the cutpoint (a problem encountered with the use of quartz substrates) and because of their ability to be used for gravimetric analysis. Particle loading tests indicated that the PCIS stages could collect up to 3.16 and of fine and coarse PM, respectively, without any loss in the collection efficiency, which would have been a result of particle bounce.

  • Development and evaluation of a personal Cascade Impactor sampler (PCIS)
    Journal of Aerosol Science, 2002
    Co-Authors: Chandan Misra, Manisha Singh, Si Shen, Constantinos Sioutas, Peter M Hall
    Abstract:

    This paper presents development and evaluation of a personal sampler for particulate matter that allows separation of airborne particles by size. The Personal Cascade Impactor Sampler (PCIS) is a miniaturized Cascade Impactor, consisting of four impaction stages, followed by an after-filter. Particles are separated in the following aerodynamic particle diameter ranges:

Chandan Misra - One of the best experts on this subject based on the ideXlab platform.

  • Field evaluation of a personal Cascade Impactor sampler (PCIS)
    Atmospheric Environment, 2003
    Co-Authors: Manisha Singh, Chandan Misra, Constantinos Sioutas
    Abstract:

    Abstract This paper presents the field evaluation of a personal Cascade Impactor sampler (PCIS). PCIS is a miniaturized Cascade Impactor, consisting of four impaction stages, followed by an after-filter. Particles are separated in the following aerodynamic particle diameter ranges: 2 O (2.7 kPa). For field evaluation, the PCIS was collocated with other samplers including the micro-orifice uniform deposit Impactor (MOUDI), scanning mobility particle sizer (SMPS) and aerodynamic particle sizer (APS) in Los Angeles and Claremont, CA. PCIS and MOUDI agree very well for coarse particulate matter (PM) (PM 2.5−10 ) mass concentrations. The fine PM (PM 2.5 ) mass as measured by PCIS is in excellent agreement with SMPS–APS measurement (∼1.02 times) and slightly higher (∼1.1 times) than the MOUDI measurements. Time-integrated (size fractionated) PM 2.5 mass, inorganic ions (nitrate and sulfate), elemental carbon (EC) and organic carbon (OC) concentrations obtained with PCIS and MOUDI were found to be in very good agreement with few differences in the 2.5 nitrate and total carbon measurements by PCIS and MOUDI using the ADI and Sunset labs monitors are in close agreement for all size fractions, indicating that any differences between MOUDI and PCIS measurements for time-integrated data might be due to artifacts associated with long-term sampling and not to differences in individual cut-points. The performance of the PCIS was also evaluated in wind tunnel tests at wind speeds up to 8 km/h. These tests showed that particle sampling efficiency and separation characteristics of the PCIS are unaffected by the wind speeds for particles up to 10 μm in aerodynamic diameter.

  • development and evaluation of a personal Cascade Impactor sampler pcis
    Journal of Aerosol Science, 2002
    Co-Authors: Chandan Misra, Manisha Singh, Si Shen, Constantinos Sioutas, Peter M Hall
    Abstract:

    This paper presents development and evaluation of a personal sampler for particulate matter that allows separation of airborne particles by size. The Personal Cascade Impactor Sampler (PCIS) is a miniaturized Cascade Impactor, consisting of four impaction stages, followed by an after-filter. Particles are separated in the following aerodynamic particle diameter ranges: <0.25, 0.25–0.5, 0.5–1.0, 1.0–2.5 and 2.5–. The PCIS operates at a flow rate of using a very high efficiency, battery-operated light pump at a pressure drop of 11 in H2O (). PTFE (Teflon), quartz and aluminum substrates were chosen for characterization of the PCIS. Laboratory tests conducted with monodisperse polystyrene latex (PSL) particles as well as polydisperse ammonium sulfate and ammonium nitrate aerosols corroborated the cutpoints. Our experimental characterization identified Teflon filters as ideal impaction substrates because they result in high collection efficiency of particles above the cutpoint of each stage without the use of adhesive coatings, do not collect excessively particles below the cutpoint (a problem encountered with the use of quartz substrates) and because of their ability to be used for gravimetric analysis. Particle loading tests indicated that the PCIS stages could collect up to 3.16 and of fine and coarse PM, respectively, without any loss in the collection efficiency, which would have been a result of particle bounce.

  • Development and evaluation of a personal Cascade Impactor sampler (PCIS)
    Journal of Aerosol Science, 2002
    Co-Authors: Chandan Misra, Manisha Singh, Si Shen, Constantinos Sioutas, Peter M Hall
    Abstract:

    This paper presents development and evaluation of a personal sampler for particulate matter that allows separation of airborne particles by size. The Personal Cascade Impactor Sampler (PCIS) is a miniaturized Cascade Impactor, consisting of four impaction stages, followed by an after-filter. Particles are separated in the following aerodynamic particle diameter ranges:

Manisha Singh - One of the best experts on this subject based on the ideXlab platform.

  • Field evaluation of a personal Cascade Impactor sampler (PCIS)
    Atmospheric Environment, 2003
    Co-Authors: Manisha Singh, Chandan Misra, Constantinos Sioutas
    Abstract:

    Abstract This paper presents the field evaluation of a personal Cascade Impactor sampler (PCIS). PCIS is a miniaturized Cascade Impactor, consisting of four impaction stages, followed by an after-filter. Particles are separated in the following aerodynamic particle diameter ranges: 2 O (2.7 kPa). For field evaluation, the PCIS was collocated with other samplers including the micro-orifice uniform deposit Impactor (MOUDI), scanning mobility particle sizer (SMPS) and aerodynamic particle sizer (APS) in Los Angeles and Claremont, CA. PCIS and MOUDI agree very well for coarse particulate matter (PM) (PM 2.5−10 ) mass concentrations. The fine PM (PM 2.5 ) mass as measured by PCIS is in excellent agreement with SMPS–APS measurement (∼1.02 times) and slightly higher (∼1.1 times) than the MOUDI measurements. Time-integrated (size fractionated) PM 2.5 mass, inorganic ions (nitrate and sulfate), elemental carbon (EC) and organic carbon (OC) concentrations obtained with PCIS and MOUDI were found to be in very good agreement with few differences in the 2.5 nitrate and total carbon measurements by PCIS and MOUDI using the ADI and Sunset labs monitors are in close agreement for all size fractions, indicating that any differences between MOUDI and PCIS measurements for time-integrated data might be due to artifacts associated with long-term sampling and not to differences in individual cut-points. The performance of the PCIS was also evaluated in wind tunnel tests at wind speeds up to 8 km/h. These tests showed that particle sampling efficiency and separation characteristics of the PCIS are unaffected by the wind speeds for particles up to 10 μm in aerodynamic diameter.

  • development and evaluation of a personal Cascade Impactor sampler pcis
    Journal of Aerosol Science, 2002
    Co-Authors: Chandan Misra, Manisha Singh, Si Shen, Constantinos Sioutas, Peter M Hall
    Abstract:

    This paper presents development and evaluation of a personal sampler for particulate matter that allows separation of airborne particles by size. The Personal Cascade Impactor Sampler (PCIS) is a miniaturized Cascade Impactor, consisting of four impaction stages, followed by an after-filter. Particles are separated in the following aerodynamic particle diameter ranges: <0.25, 0.25–0.5, 0.5–1.0, 1.0–2.5 and 2.5–. The PCIS operates at a flow rate of using a very high efficiency, battery-operated light pump at a pressure drop of 11 in H2O (). PTFE (Teflon), quartz and aluminum substrates were chosen for characterization of the PCIS. Laboratory tests conducted with monodisperse polystyrene latex (PSL) particles as well as polydisperse ammonium sulfate and ammonium nitrate aerosols corroborated the cutpoints. Our experimental characterization identified Teflon filters as ideal impaction substrates because they result in high collection efficiency of particles above the cutpoint of each stage without the use of adhesive coatings, do not collect excessively particles below the cutpoint (a problem encountered with the use of quartz substrates) and because of their ability to be used for gravimetric analysis. Particle loading tests indicated that the PCIS stages could collect up to 3.16 and of fine and coarse PM, respectively, without any loss in the collection efficiency, which would have been a result of particle bounce.

  • Development and evaluation of a personal Cascade Impactor sampler (PCIS)
    Journal of Aerosol Science, 2002
    Co-Authors: Chandan Misra, Manisha Singh, Si Shen, Constantinos Sioutas, Peter M Hall
    Abstract:

    This paper presents development and evaluation of a personal sampler for particulate matter that allows separation of airborne particles by size. The Personal Cascade Impactor Sampler (PCIS) is a miniaturized Cascade Impactor, consisting of four impaction stages, followed by an after-filter. Particles are separated in the following aerodynamic particle diameter ranges: