EXPERIMENTAL STUDY ON THE EFFECT OF EVAPORATIVE COOLING ON THE THERMAL RESPONSE OF COMMERCIAL FIRE SPRINKLERS

摘要

A new model to predict the activation time of fire suppression sprinklers is validated experimentally. The model extends the range of applicability of previous formulations to allow for the presence of water droplets in the fire plume. The presence of water droplets in the hot gas flow is due to the activation of the first sprinkler. The droplets are carried by the gas and deposited on the surrounding sprinklers, where they evaporate. The vaporization process cools the sprinklers and this causes a delay in their activation. Three sets of commercially available sprinklers are tested under three different boundary conditions. The experimental results show good agreement with the predictions of the model within the uncertainties associated with the measurements. The influence of the sprinkler frame orientation on the evaporative cooling is also discussed in this paper.