SOME FACTORS INFLUENCING THE EFFICIENCY OF A JET NEBULIZER SYSTEM

The operation of a commercially available nebuliser system (Medic-Aid Ltd.) is reviewed and the efficiency with which it produces an aerosol assessed. Defining the efficiency of nebulisation E as the fraction of the original mass of solution released as an aerosol it is found that the internal surface area, mass of solution used, the surface tension of the solution and the angle of tilt are important factors in determining E. Reducing the internal surface area of the nebuliser by means of Perspex inserts significantly increases E for 3 g of water from 49% for the unmodified system to 67% for the modified nebuliser (P<0.01). E increases with the mass of solution used, but only exceeds 60% when 4.5 g water are used. Decreasing the surface tension of the solution from 7.2*10-3 N m-1 (water) to 3.7*10-3 N m-1 and 3.1*10-3 N m-1 (using two different concentrations of a detergent in water) significantly increases E for 3 g solution from 49% to 65% and 69% respectively (P<0.05). Operating the nebuliser at a tilt also increases E.