AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Performance Testing of MSP Model 1120 Water-based Condensation Particle Counter
LIN LI, Francisco Romay, William Dick, MSP Corporation
Abstract Number: 44 Working Group: Instrumentation and Methods
Abstract A condensation particle counter (MSP Model 1120) that uses water as the working fluid has been recently introduced. One critical aspect of its performance is the effect of the particle composition on the induced growth before counting. For a water-based particle counter, there is a difference between hydrophobic and hydrophilic particles. The temperature of the saturator, which provides a water-vapor-saturated stream, also affects the minimum particle size that can be activated.
In this study, the performance of the Model 1120 water-based condensation particle counter (WCPC) was characterized for several aerosol compositions, including silver, sodium chloride, sucrose and silica particles generated by evaporation-condensation or by electrospray techniques. All particles were size-classified using a short differential mobility analyzer (DMA) to select monodisperse test aerosols. The challenge aerosol was mixed uniformly with clean makeup air and split between the WCPC and an aerosol electrometer, which was used as the reference instrument to determine the counting efficiency. The D50 (i.e., the particle diameter with 50% counting efficiency) of the WCPC was somewhat dependent on aerosol composition (mainly hygroscopicity). The saturator temperature of the WCPC was also varied in the tests. As expected, D50 values decreased with increasing saturator temperatures.