A laminar-flow, water-based condensation particle counter (WCPC)

Susanne V. Hering, Mark R Stolzenburg, Frederick R. Quant, Derek R. O'Berreit, Patricia B. Keady

Research output: Contribution to journalReview articlepeer-review

154 Scopus citations

Abstract

A new water-based condensation particle counter (WCPC) is presented. The WCPC is a thermally diffusive, laminar flow instrument. Condensational enlargement is achieved through the introduction of a saturated airflow into a "growth tube" with wetted walls held at a temperature higher than that of the entering flow. An unsheathed, 1 L/min instrument utilizing this principle has been evaluated with various aerosols. The particle size detected with an efficiency of 50% is at or below 4.8 nm for particles sampled from vehicular emissions or ambient air, and for various laboratory-generated inorganic salts. The cut point is higher for the organic materials tested, ranging from 8 nm to 30 nm depending on the compound and purity level. An empirically determined dead-time correction factor is applied to the coincidence correction, which allows extension of the single-count mode to higher concentrations. The counting efficiencies for 80 nm oil and salt aerosols are equal, and above 97% for concentrations approaching 105 cm -3. When subject to a step-fucntion change in input concentration the time required to attain 90% of the final value, including a 0.5 s lag, is 1.3 s. The corresponding exponential time constant is 0.35 s. The WCPC evaluated here is marketed as the TSI Model 3785.

Original languageEnglish (US)
Pages (from-to)659-672
Number of pages14
JournalAerosol Science and Technology
Volume39
Issue number7
DOIs
StatePublished - Jul 1 2005

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