A scanning mobility particle sizer (SMPS) is an analytical instrument that measures the size and number concentration of aerosol particles with diameters from 2.5 nm to 1000 nm.[1] They employ a continuous, fast-scanning technique to provide high-resolution measurements.
The particles that are investigated can be of biological or chemical nature. The instrument can be used for air quality measurement indoors, vehicle exhaust,[2] research in bioaerosols, atmospheric studies, and toxicology testing.
Principle of operationedit
The air to be analyzed is pumped through an ionizing source (or neutralizer) which will establish a known charge distribution. Then, exposure to an electric field in the DMA will isolate a certain particle diameter, which is a function of the voltage generating the field (a voltage value corresponding to a particle diameter value that passes through the DMA). Finally, these particles of the same diameter will be counted by an optical device (CPC).[3] The air inlet to be analyzed can be equipped with an impaction head.
Impaction headedit
An impaction head, or fractionator head, is a device that uses the principles of fluid mechanics to trap, by their inertia, the largest particles present in the air. The sampling inlet of the SMPS is thus protected from large dust and insects, the air that enters it contains only the fine particles to be quantified.[4] These are usually called "PM10 inlet" or "PM2.5 inlet".
Neutralizeredit
The air flow then passes through an ionizing source. The sampled air will be exposed to high concentrations of positive and negative ions, after a certain number of collisions the charge distribution will be stable and known. The neutralizer is also used to eliminate electrostatic charges from aerosol particles. The charge distribution from the neutralizer is a balanced charge distribution that follows Boltzmann's law.[5]
DMA (Differential Mobility Analyzer)edit
The sample then enters a differential mobility analyzer. The air and aerosol (whose charge distribution is now balanced and known) are then introduced into an air flow channel. A central tubular electrode, and another concentric one, generate an electric field in this fluid path. In the channel, the particles are subjected to a uniform electric field and an air flow. The particles then move at a speed that depends on their electrical mobility. At a given voltage, only particles of a certain diameter will follow this channel until they exit; the smaller and larger will crash into the electrodes.[6]
CPC (Condensation particle counter)edit
The air now contains only particles of a certain diameter. The flow is introduced into a CPC, a condensation particle counter, which measures the concentration of particles in an aerosol sample. The CPC works by using butanol vapor condensation on the particles present in the air sample. The particles are exposed to butanol vapor heated to 39 °C. The butanol vapor condenses on the particles, increasing their size and thus facilitating their optical detection. The particles are then exposed to a laser beam, and each particle scatters light. The peaks of scattered light intensity are continuously counted and expressed in particles/cm3.
Resultsedit
The results obtained by this type of device therefore include the distribution of particle sizes in the air continuously. The DMA will generate voltage back-and-forth between its electrodes from 0 to 10,000 V, corresponding to a measurement range of 8 nm to 800 or 1000 nm, and the CPC will quantify each of these diameters.
Referencesedit
^Lev Solomonovich Ruzer; Naomi H. Harley (2013). Aerosols Handbook: Measurement, Dosimetry, and Health Effects (Second ed.). CRC Press. pp. 234–. ISBN978-1-4398-5519-5. Retrieved 28 April 2013.
^Burtscher, H. (2005). "Physical characterization of particulate emissions from diesel engines: a review". Journal of Aerosol Science. 36 (7): 896–932. Bibcode:2005JAerS..36..896B. doi:10.1016/j.jaerosci.2004.12.001. ISSN 0021-8502.
^University of Manchester, "Scanning Mobility Particle Sizer (SMPS)", http://www.cas.manchester.ac.uk, . (retrieved 21 december 2023.)
^Journal of the Air & Waste Management Association, "On the techniques and standards of particulate matter sampling", https://www.tandfonline.com. (retrieved 18 january 2024.)
^Journal of chemical engineering of Japan, "Electrical neutralization of charged arerosol particles by bipolar ions ", https://www.jstage.jst.go.jp/, Journal of chemical engineering of Japan. (retrieved 14 january 2024.)
^University of Manchester, "Scanning Mobility Particle Sizer (SMPS)", http://www.cas.manchester.ac.uk, . (retrieved 21 december 2023.)
April 11, 2024
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A scanning mobility particle sizer SMPS is an analytical instrument that measures the size and number concentration of aerosol particles with diameters from 2 5 nm to 1000 nm 1 They employ a continuous fast scanning technique to provide high resolution measurements Contents 1 Applications 2 Principle of operation 2 1 Impaction head 2 2 Neutralizer 2 3 DMA Differential Mobility Analyzer 2 4 CPC Condensation particle counter 2 5 Results 3 ReferencesApplications editThe particles that are investigated can be of biological or chemical nature The instrument can be used for air quality measurement indoors vehicle exhaust 2 research in bioaerosols atmospheric studies and toxicology testing Principle of operation editThe air to be analyzed is pumped through an ionizing source or neutralizer which will establish a known charge distribution Then exposure to an electric field in the DMA will isolate a certain particle diameter which is a function of the voltage generating the field a voltage value corresponding to a particle diameter value that passes through the DMA Finally these particles of the same diameter will be counted by an optical device CPC 3 The air inlet to be analyzed can be equipped with an impaction head Impaction head edit An impaction head or fractionator head is a device that uses the principles of fluid mechanics to trap by their inertia the largest particles present in the air The sampling inlet of the SMPS is thus protected from large dust and insects the air that enters it contains only the fine particles to be quantified 4 These are usually called PM10 inlet or PM2 5 inlet Neutralizer edit The air flow then passes through an ionizing source The sampled air will be exposed to high concentrations of positive and negative ions after a certain number of collisions the charge distribution will be stable and known The neutralizer is also used to eliminate electrostatic charges from aerosol particles The charge distribution from the neutralizer is a balanced charge distribution that follows Boltzmann s law 5 DMA Differential Mobility Analyzer edit The sample then enters a differential mobility analyzer The air and aerosol whose charge distribution is now balanced and known are then introduced into an air flow channel A central tubular electrode and another concentric one generate an electric field in this fluid path In the channel the particles are subjected to a uniform electric field and an air flow The particles then move at a speed that depends on their electrical mobility At a given voltage only particles of a certain diameter will follow this channel until they exit the smaller and larger will crash into the electrodes 6 CPC Condensation particle counter edit The air now contains only particles of a certain diameter The flow is introduced into a CPC a condensation particle counter which measures the concentration of particles in an aerosol sample The CPC works by using butanol vapor condensation on the particles present in the air sample The particles are exposed to butanol vapor heated to 39 C The butanol vapor condenses on the particles increasing their size and thus facilitating their optical detection The particles are then exposed to a laser beam and each particle scatters light The peaks of scattered light intensity are continuously counted and expressed in particles cm3 Results edit The results obtained by this type of device therefore include the distribution of particle sizes in the air continuously The DMA will generate voltage back and forth between its electrodes from 0 to 10 000 V corresponding to a measurement range of 8 nm to 800 or 1000 nm and the CPC will quantify each of these diameters References edit Lev Solomonovich Ruzer Naomi H Harley 2013 Aerosols Handbook Measurement Dosimetry and Health Effects Second ed CRC Press pp 234 ISBN 978 1 4398 5519 5 Retrieved 28 April 2013 Burtscher H 2005 Physical characterization of particulate emissions from diesel engines a review Journal of Aerosol Science 36 7 896 932 Bibcode 2005JAerS 36 896B doi 10 1016 j jaerosci 2004 12 001 ISSN 0021 8502 University of Manchester Scanning Mobility Particle Sizer SMPS http www cas manchester ac uk retrieved 21 december 2023 Journal of the Air amp Waste Management Association On the techniques and standards of particulate matter sampling https www tandfonline com retrieved 18 january 2024 Journal of chemical engineering of Japan Electrical neutralization of charged arerosol particles by bipolar ions https www jstage jst go jp Journal of chemical engineering of Japan retrieved 14 january 2024 University of Manchester Scanning Mobility Particle Sizer SMPS http www cas manchester ac uk retrieved 21 december 2023 Retrieved from https en wikipedia org w index php title Scanning mobility particle sizer amp oldid 1198667298, wikipedia, wiki, book, books, library,
