This article reports on an investigation of the influence of gas flow rate and liquid flow rate on the droplet sizes and velocities produced by a linear atomizer. Two-component phase doppler interferometry (PDI) is applied to a water spray to quantify the spray characteristics as a function of operating conditions. The point measurements are combined into a composite Sauter mean diameter (SMD) so that Be data of droplet size experimentally determined by PDI can be compared with those calculated using an existing correlation. The present results demonstrate that: (1) droplet size decreases with an increase in atomizing gas pressure, i.e., the averaged SAID decreases from 82.3 mu m to 51.3 mu m when atomizing gas pressure increases from 1.378 x 10(5) Pa (20 psi) to 2.067 x 10(5) Pa (30 psi); (2) droplet velocity increases with atomizing gas pressure, i.e., the droplet velocity of 11- to 20-mu m size range increases from 61.0 m/s to 80.0 mis when the atomizing gas pressure increases from 1.378 x 10(5) Pa (20 psi) to 2.067 x 10(5) Pa (30 psi); and (3) the liquid height inside the crucible has little influence on liquid flow rate. Comparison of the measured SAID with the calculated SAID suggests that: (1) velocity of 11- to 20-mu m droplets obtained by PDI may be used validly to estimate the atomizing gas velocity, and (2) the atomization efficiency has a significant influence on SMD and must be considered.