Collection efficiency and interstage loss of nanoparticles in micro-orifice-based cascade impactors

Design and Testing of the NCTU Micro-Orifice Cascade Impactor (NMCI) for the Measurement of Nanoparticle Size Distributions

“…The d pa50 of the 7th-10th stages of the NMCI was shown to be very close to the nominal values given in Marple et al (1991). Liu et al (2013) concluded that the nanoparticle loss in the 10th stage of the NMCI and the MOUDI should be considered when determining the mass distributions of nano-particles.…”

“…The design of the nozzle plates of Liu et al (2013) was also shown to improve the problem of nozzle clogging which results in an increase in the pressure across the cascade impactors and a decrease in the d pa50 values of the lower stages. As compared to the fragile structure of the existing nozzle plates of the MOUDI, the nozzle plates of Liu et al (2013) with a sturdy nozzle structure allow ultrasonication of the nozzle plates for better cleaning efficiency of deposited particles in the nozzles.…”

“…As compared to the fragile structure of the existing nozzle plates of the MOUDI, the nozzle plates of Liu et al (2013) with a sturdy nozzle structure allow ultrasonication of the nozzle plates for better cleaning efficiency of deposited particles in the nozzles. The nozzle strength test for the 9th-stage nozzles of the NMCI was further conducted in this study.…”

“…However, the loss for nanoparticles in all stages was not tested. In our recent study, the NCTU micro-orifice cascade impactor (NMCI) was developed and tested to avoid possible particle clogging in the nozzles using new nozzle plates with smooth nozzle shape of 120 mm in thickness fabricated by the LIGA (Lithography, Electroplating, and Molding) process to replace the 7th-10th stages in one of the MOUDI (MSP Model 110) (Liu et al 2013). The NMCI and the MOUDI were studied for the particle collection efficiency and nanoparicle interstage loss.…”

“…Cascade impactors are widely used to measure aerosol mass size distributions and collect samples for chemical analysis (Zhu et al 2010(Zhu et al , 2012Chen et al 2010Chen et al , 2013Kim et al 2012;Kudo et al 2012;Canepari et al 2013;Li et al 2013;Liu et al 2013;Fang et al 2014;Lin et al 2014). Commercial cascade impactors with the cutoff aerodynamic diameter (d pa50 ) covering the nanosize range include the micro-orifice uniform deposit impactor (MOUDI) (MSP Corp., Shoreview, MN, USA; Marple et al 1991), the quartz crystal microbalance (QCM) cascade impactor (California Measurements, Inc., Sierra Madre, CA, USA ;Chaun 1970), and the electric low-pressure impactor (ELPI) (Dekati Ltd.; Keskinen et al 1992).…”