Annular aspiration slot entry efficiency of the CIP-10 aerosol sampler

Abstract

The CIP-10 personal or static aerosol sampler is designed to sample the respirable, thoracic or inhalable aerosol fraction by using the appropriate selector. All these versions have the same downward-oriented annular aspiration slot. The annular slot entry efficiency at a flow rate of 10 l min^–1 was studied as a static sampler in an experimental wind tunnel, at first for a 1 m s^–1 wind velocity. Glass beads were generated as a test aerosol by a fluidized bed aerosol generator. A sharp-edged thin-walled isokinetic probe was used for reference sampling. The particle size-dependent efficiency was deduced from the particle size distributions of both reference and annular slot samples. Particle size distributions were measured as functions of the volume equivalent diameter D_v by the Coulter Multisizer technique. The aerodynamic particle diameter D_ae was deduced from D_v by using particle density and Reynolds number. The entry efficiency of the CIP-10 annular aspiration slot at 1 m s^–1 is between 0.9 and 0.4 for the whole range of particle aerodynamic diameters within the range 10–60 µm. By minimizing the inner particle deposit under the protecting cup of the selector, the instrument can meet the CEN sampling criteria for sampling of inhalable aerosol as shown on the bias and accuracy maps.