Methodology for measuring PM2.5 separator characteristics using an Aerosizer

A method is presented that enables the measurement of the particle size sep aration characteristics of an inertial separator in a rapid fashion. Overal l penetration is determined for discrete particle sizes using an Aerosizer (Model LD, TSI, Inc., Particle Instruments/Amherst, Amherst, MA) time-of-fl ight measurement device by comparing the number concentration of particles penetrating through a separator to the concentration entering the separator . Critical measurements of separator characteristics are determined using a vibrating orifice aerosol generator to produce the challenge aerosol. Meas urements of penetration requiring less precision and accuracy may be determ ined using nebulized suspensions of polystyrene latex microspheres as the c hallenge aerosol, The time for measuring a single penetration curve can be reduced from a week using vibrating orifice aerosol to fewer than 2 h using polystyrene latex microsphere aerosol. Validation of the penetration deter mined with this method was made by comparison to fluorometric techniques. I t is estimated that penetration may be measured with an accuracy of +/-4%, which is equivalent to an uncertainty of approximately 0.04 mum in cutpoint diameter determination for PM2.5 separators, The overall accuracy in deter mining a cutpoint diameter of a PM2.5 separator (including uncertainty in t he creation of test aerosols) is estimated to be better than +/-0.09 mum.