The paper presents the theoretical and experimental aspects concerning the droplet evaporation processes from the liquid jet, sprayed in an air vapour mixture. From the particularities of the transfer phenomena involved in the droplet evaporation, the lifetime evolution of this, as a function of liquid temperature, its dimension and the surroundings humidity, is displayed. The surroundings consist in a semi-open room in which we may control the entry of the fresh air. Based on these theoretical approaches the test bench was developed. The aspects regarding the experimental tests are mentioned as the jet development followed by the evaporation quality. The experimental diagrams concerning the chart of temperature and humidity inside and near the two-phase jet are shown. The practical values of the measured parameters allow us to use the jet device with a warm liquid in the extinguish system. The tests were realised with various liquid temperature for the gaseous hydrocarbon flame. From the experiment it was observed that the liquid phase in contact with the flame evaporates instantaneously forming the superheated vapour. Consequently, the vapour huge volume generated on this way will decrease the oxygen concentration in the mixture, which may fall it under the ignition limit. On the other hand, the surrounding temperature reduces due to the heat absorption during the liquid evaporation. These two phenomena, which act on the flame, rise the extinguish efficiency of the two-phase jet.

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