Cascade impactor design and performance

Newton, G.J.; Raabe, Otto G.; Mokler, Brian V.

doi:10.1016/0021-8502(77)90021-0

Cited by 75 publications

(28 citation statements)

References 11 publications

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“…A Marple cascade impactor (Model 260, Sierra Instruments, Carmel Valley, CA) and a Lovelace multijet impactor (Newton et al, 1977) were used in an attempt to separate talc aerosol. Because of high aerosol concentrations, heavy particle deposits on impactor substrates did not allow close examination of individual particles.…”

Section: Aerodynamic Classification Of Aerosolsmentioning

confidence: 99%

Dynamic Shape Factor of a Plate-Like Particle

Cheng

Yeh

Allen

1988

Aerosol Science and Technology

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Talc aerosol particles found in work enviromnents have plate-like shapes. These particles are difficult to characterize by their physical dimensions or their aerodynamic behavior. This paper describes a detailed study of the physical and aerodynamic properties of a commercial-grade, respirable talc aerosol and establishes a relationship between the projected area diameter (D,) and the aerodynamic resistance diameter (D,). The measured bulk density was 3.04 g/cn?. Electron micrographs showed that the particles were plate-like with a fairly constant thickness-to-diameter ratio of 0.096. The aerosol was aerodynamically separated in an aerosol centrifuge, and was collected flat on the substrate. The dynamic shape factor of the size-classified talc particle was calculated to be 1.88, which is in good agreement with the theory based on an oblate spheroid moving with its short axis parallel to the flow. The aerodynamic resistance diameter (Dar) was linearly related to the projected area diameter (D,) by the relationship D, = 0.67 D, Jm, where C(D,) is the slip correction factor 'based on the adjusted sphere diameter ( D , = 1.21 D,).

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Section: Aerodynamic Classification Of Aerosolsmentioning

confidence: 99%

Dynamic Shape Factor of a Plate-Like Particle

Cheng

Yeh

Allen

1988

Aerosol Science and Technology

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“…The serial sampling train consists of a seven-stage Lovelace multijet impactor (Newton, et al, 1977) in tandem with the PFDB (Figure 3) and is operated at a flow rate of 14.7 lpm. Stainless steel substrates coated with grease are used for collection surfaces in the cascade impactor.…”

Section: Lovelace Multijet Cascade Impactor/ Parallel-flow Diffusion mentioning

confidence: 99%

Size Characterization of Carbonaceous Particles Using a Lovelace Multijet Cascade Impactor / Parallel-Flow Diffusion Battery Serial Sampling Train

Barr

Cheng

Yeh

et al. 1989

Aerosol Science and Technology

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A serial sampling train consisting of a Lovelace multijet cascade impactor (LMJI) and a seven cell parallel-flow diffusion battery (PFDB) has been used to provide a comprehensive method for suing aerosols with a wide size distribution ranging from less than 0.01 pm to over 10 pm. The fraction of the aerosol greater than 0.7 pm is collected by the impactor. The remaining fraction of the aerosol is sampled by the PFDB. Design of the PFDB is based on the theory of a screen-type diffusion battery. The concept of parallel flow is employed to provide a method for sampling aerosols that fluctuate too rapidly in concentration and size distribution to be measured by conventional methods. The LMJI/PFDB sampling system is useful for characterizing multimodel sue distributions such as those that occur in ambient aerosols. It can also be used to determine the chemical composition of collected samples as a function of particle size. This sampling system has been used to size classify diesel and diesel-oil shale exposure atmospheres, and benzo(a)-pyrene-coated carbon black aerosols. The diffusion equivalent diameter (D,,) of the diesel exhaust was 0.07-0.08 pm, and the oil-shale dust had a mass median aerodynamic diameter (MMAD) of 2.6-2.9 pm. The size distribution of the carbon black aerosol was bimodal, with the fine fraction having a D, , of 0.2 pm, and the coarse fraction having a MMAD of 2.0 pm.

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“…This aerosol was sampled by the present two-stage virtual impactor and by a Lovelace Multijet Cascade Impactor (LMJ) designed using Marple's criteria and characterized against other models of cascade impactors (Newton et al, 1977). Table 3 compares measurement results to two expected particle size distributions generated by the nebulizer.…”

Section: Resultsmentioning

confidence: 99%