In order to reduce the particle deposition on the tube wall a
laminar flow was guaranteed in every sub-section of the sampling
line (maximum Reynolds number is about 500). The total particle
residence time in the sampling line before the entrance in the measurement
device is about 5 s. Besides, since the aerosol is not thermo-
conditioned only in the tube connecting the Thermal
Conditioner to the CPC (or SMPS), it is important to reduce this
length as much as possible. In the presented measurement chain
a 40 cm duct was used; its particle residence time is shorter than
0.5 s ensuring a negligible artefact in the measurements carried
out. In particular, measurements were performed setting a CPC
flow rate of 1.5 L min1. Conditioning temperatures for the Rotating
Disk and Thermal Conditioner were set at 120–150 C obtaining
a primary dilution ratio (Rotating Disk) of 1:77 and a
secondary dilution ratio (Thermal Conditioner) of 1:1.3, leading
to a global dilution factor equal to 1:100.