An experimental investigation was performed to characterize the stability of gas-liquid sprays. An industrial-scale testing system was used, in which water and air were mixed upstream and flowed through a feeding pipe to the nozzle. Numerous flow conditions within the range of 1-4 kg/min of air and 75.7-181.7 kg/min of water were considered, for three different feeding pipe lengths (L/D = 16, 41, 74). The spray stability was characterized based on the analysis of the wall pressure fluctuations in the amplitude, time, and frequency domains. A parameter based on the mean square value of the pressure fluctuations for frequencies below 40 Hz was used to quantify the spray stability. High-speed videos showed the flow pattern entering the nozzle, directly affecting the spray stability, with dispersed-bubble and intermittent flow yielding stable and unstable sprays, respectively. Different lengths of feeding pipes affected the stability through changes to the equilibrium condition (i.e., flow development) of the two-phase flow entering the nozzle.