Abstract Number: 283 Working Group: Instrumentation and Methods
Abstract There is an increasing demand for measuring airborne nanoparticles in real time. Condensation particle counters (CPC) are the instruments which can measure the real-time nanoparticle concentration, however, they cannot distinguish the particle sizes. Therefore we need a sampling inlet of CPC for nanoparticles, i.e., a classifier for Dp<100 nm. Impactors are commonly used as a low-pass filter but they must be operated at a reduced pressure to attain 100 nm cutoff size, which makes it difficult to use the impactors with CPC. Recently we have developed Inertial Filter (IF) which can classify nanoparticles with a fibrous filter at a low pressure drop. In the present work, IF made of TEM grids was applied to CPC as a PM0.1 sampling inlet and the collection performance of IF was evaluated. As a result, a decrease in the collection efficiency was observed for particles larger than 100 nm due to the bounce-off of particles at a high impaction velocity (about 30 m/s), and the collection efficiency was largely influenced by the orientation of TEM grids in each layer. Coating of TEM grids with Oleic cid suppressed the bounce-off of particles, and the layering of TEM grids with a minimal overlapped area led to the maximum collection efficiency. Taking these special cautions into account, IF was found to achieve 100 nm cutoff size in aerodynamic diameter even for the sampling flow rate of 1 L/min. The applications of IF for real-time monitoring of sub-100 nm aerosol is also discussed.