The effect of vents on the opening of the first sprinklers

Abstract The interaction between roof vents and sprinklers is being studied in a Joint Project by the U.K. Fire Research Station and Colt International Ltd. following a review of the problem by Heselden. His original model has been extended and this paper describes its use to estimate the effects of roof venting on the opening of the first sprinklers. The importance of mixing in determining the radial temperature distribution is demonstrated. Generally the effects of venting are second-order ones compared with such factors as the rate of growth of fire, the nominal operating temperatures of the sprinklers and, with a rapidly growing fire, the time constant of the sprinklers. Except possibly in small compartments (700 m2 or less in area) there appears to be little justification for the recommendation that vents should not open before sprinklers.