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Impactors for Aerosol Measurement: Developments and Sampling Biases


Biswas, Pratim (1985) Impactors for Aerosol Measurement: Developments and Sampling Biases. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/YG7P-PX37.


This work is subdivided into four parts. The first part consists of characterizing high jet velocity impactors, developing their scaling criteria to facilitate instrument design and prediction of impactor performance under conditions where no calibration data are available.

The second part discusses the problem of distortion of size distributions by aerosol sampling instruments because of particle size changes occurring due to vapor or condensable phase transport to and from the particles. The severity of the problem is demonstrated both theoretically and experimentally for a few commonly used aerosol sampling instruments.

The third part is the development of a 'Particle Trap Impactor' working on the virtual impaction principle. The inherent problems of bounce and re-entrainment in conventional impactors is minimized, without the addition of substrates such as grease, in these impactors. The result of operating the unit at high temperature is also discussed.

The final part is the calculation of the scavenging rate of particles due to differential impaction. The results are used to determine upperbounds on the number concentration of particles entering the impactor to minimize biasing the measurements.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Impactors; High Velocity Impactors; Sampling Biases; High Temperature Impactors; Particle Trap Impactors; Virtual Impactors
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Mechanical Engineering
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Flagan, Richard C.
Thesis Committee:
  • Flagan, Richard C. (chair)
  • Cass, Glen Rowan
  • Seinfeld, John H.
  • Brennen, Christopher E.
  • Sabersky, Rolf H.
Defense Date:29 October 1984
Funding AgencyGrant Number
Environmental Protection Agency (EPA)EPA-R-809010101
Record Number:CaltechETD:etd-04102008-112738
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1332
Deposited By: Imported from ETD-db
Deposited On:17 Apr 2008
Last Modified:21 Dec 2019 01:59

Thesis Files

PDF (Biswas_p_1985.pdf) - Final Version
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