Discussion of thermal activation on heat collection plate of sprinkler heads

Abstract

Heat collection plates (HCP) are installed above sprinkler heads in some tall halls in the Asia-Oceania region to give faster thermal actuation. In this study, experiments were thus conducted in a fire chamber to determine thermal activation times of sprinkler heads with and without HCP. Three HCP with different diameters were selected and tested with pendent fast response liquid-in-bulb sprinkler heads. A total of 48 sprinklers heads were studied under different conditions of height and pool fire size. The HCP was found to reduce sprinkler activation time in a fire chamber test by up to 61%. Thermal activation time of sprinkler heads was also investigated by the common plunge test in a wind tunnel. Results indicate that activation was delayed by 5%, 18%, and 221% on average by the three HCP. An HCP of pie plate shape with small diameter would alter the physical scenario of heating up the heat sensing element of sprinkler heads assumed in the plunge test. Therefore, the effect of HCP cannot be appropriately assessed in a wind tunnel.