Use of porous foam as the substrate of an impactor for respirable aerosol sampling

The effect of a porous foam substrate on the penetration characteristics of an impactor with a single round nozzle was investigated experimentally, with liquid and solid particles in the size range of 1-10μm. The experimental results show that the cut-off aerodynamic diameter of the impactor with porous foam substrate is lower than that with porous metal substrate due to more air penetration into the porous foam; in addition, the impactor penetration curve is less sharp. A numerical simulation of the penetration curve for the impactor with porous foam substrate was in good agreement with the experimental data. The numerical method was then used to find the best sampling flow rate for respirable aerosol sampling. Results show that when the nozzle diameter is 0.36 cm and the sampling rate is 1.9l/min, the penetration curve of the impactor with the porous foam is very close to the criteria for respirable aerosol sampling.