On operation of the ultra-fine water-based CPC TSI3786 and comparison with other TSI models (TSI3776, TSI3772, TSI3025, TSI3010, TSI3007)

In this study we examined performance characteristics of an ultrafine water condensation particle counter (UWCPC, TSI3786). The detection efficiency was investigated using different temperature differences between saturator and growth tube. The cut-sizes D90, D50, D10, and D0 were determined by fitting a two-free-parameter equation to the experimental data. The determined cut-sizes were comparable (+/- 8%) with other two widely used fitting equations. The cut-sizes were studied changing the growth tube temperature from 65 to 78 degrees C and varying the saturator temperature from 8 to 20 degrees C. For silver particles the smallest detected cut-size D50 was 2.9 nm, and the largest one -4.5 nm, and in default operation conditions it was 3.9 nm. Additionally, the effect of particle chemical composition on the detection efficiency was studied. The cut-sizes D50 were 2 2.9, 2.3, and 1.8 nm for silver, ammonium sulfate, and sodium chloride particles, respectively. A concentration calibration was performed with high particle number concentrations. Within +/- 10% accuracy the highest reliable measured number concentration was 100000 cm(-3). The determined detection efficiency of the UWCPC was compared with other commercial CPCs (TSI3785, TSI3776, TSI3772, TSI3025, TSI3010, TSI3007) using default operation regimes of the instruments. The results show that the tested UWCPC has a larger cut-size for silver particles than do butanol-based ultrafine CPCs (TSI3776, TSI3025), but smaller cut-size than other tested TSI CPCs. In default operation regime, the tested TSI3776 had the lowest detection limit (D50% = 3.2 nm) of the silver particles, and the corresponding size of TSI3025 was 3.6 nm.