Design and Characterization of a New, Water-Based, High Sample-Flow Condensation Nucleus Counter

Abstract

We describe the development and performance of a new, continuous-ow, single-particle, condensation nucleus counter (CNC) that uses water as its working uid. Supersaturation is generated both through mixing of the ambient temperature sample gas stream with a hot saturated gas stream and by cooling of this mixed gas stream. Nucleation and condensation upon the entrained particles occurs within a cooled growth tube and a laser-based optical counter detects the enlarged particles. This Modi ed-Mixing CNC (MMCNC) samples gas at 0.5 cfm (14.1 lpm), has a false count rate of 0.012/cf, and has a unity counting ef ciency for NaCl particles larger than 12 nm in diameter. These attributes make it an ideal instrument for next-generation cleanroom monitoring, where it can be plumbed into an existing DI water line and run without the need for frequent maintenance. Its use of water and high ow rate may also give it a unique advantage for atmospheric and indoor air research applications. We characterize the MMCNC's performance by varying four critical variables affecting its operation. A simple model accounting for heat and mass transfer to the growth tube is successful at predicting the relative importance of each of these variables and in estimating the average supersaturation in the growth tube.

Performance Evaluation of an Improved Particle Size Magnifier (PSM) for Single Nanoparticle Detection

“…Various modification and applications of the PSM have been reported by several investigators (Okuyama et al 1984(Okuyama et al , 1987Seto et al 1997;Gamero-Castaño and Fernández de la Mora 2000). Other studies on alternative mixing-type CNCs (MTCNC) meant for detecting larger particle sizes have been reported by Parsons and Mavliev (2001), Mavliev (2002), Wang et al (2002), and Kim et al (2002). Table 1 shows the relevant specification for several kinds of recent PSM and Mixing-Type CNC (MTCNC).…”