Effect of Evaporative Cooling on the Activation Time of Fire Sprinklers.
Effect of Evaporative Cooling on the Activation Time of
Ruffino, P.; diMarzo, M.
Fire Safety Science. Proceedings. Seventh (7th)
International Symposium. International Association for
Fire Safety Science (IAFSS). June 16-21, 2003,
Worcester, MA, Intl. Assoc. for Fire Safety Science,
Boston, MA, Evans, D. D., Editor(s), 481-492 pp, 2003.
Sponsor:National Institute of Standards and Technology,
fire research; sprinklers; evaporation; cooling;
activation time; sprinkler activation; equations
Arrays of fire sprinklers are installed in buildings to
protect the property and their occupants against the
damages of fire. When a fire occurs, the sprinkler
closest to the fire location typically activates first
and releases water droplets into the rising plume of hot
gases. Part of these droplets is entrained by the plume
and may impact on adjacent sprinklers providing
evaporative cooling and thus delaying their activation.
The current model that simulates the thermal response of
fire sprinklers does not include this evaporative
cooling effect; therefore, a new model is proposed to
extend the applicability of the previous formulation.
The new model includes one parameter, determined
experimentally, that is associated to the evaporative
cooling effect. Commercially available sprinklers are
tested to assess the accuracy of the proposed model for
a range of conditions (hot gas temperature and velocity,
water volumetric fraction and sprinkler orientation with
respect to the flow).