TY - JOUR
T1 - A laminar-flow, water-based condensation particle counter (WCPC)
AU - Hering, Susanne V.
AU - Stolzenburg, Mark R.
AU - Quant, Frederick R.
AU - O'Berreit, Derek R.
AU - Keady, Patricia B.
PY - 2005/7
Y1 - 2005/7
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=20044395869&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=20044395869&partnerID=8YFLogxK
U2 - 10.1080/02786820500182123
DO - 10.1080/02786820500182123
M3 - Review article
AN - SCOPUS:20044395869
SN - 0278-6826
VL - 39
SP - 659
EP - 672
JO - Aerosol Science and Technology
JF - Aerosol Science and Technology
IS - 7
ER -