Effect of heat collector plate on thermal sensitivity of sprinkler heads in large terminal Halls

Heat collector plates (HCP) are commonly installed above sprinkler heads in large halls with perforated ceilings, such as in high-speed railway terminals. The thermal sensitivity of a pendent type 68 °C liquid-in-bulb sprinkler head operating with and without the HCP was investigated in this paper. Sprinkler heads were first tested in a fire chamber under a common scenario at an early stage of a fire. Air temperatures next to the sprinkler head were measured by thermocouples. It is observed that HCP gives a shorter activation time. Additionally, the standard plunge test in a wind tunnel for evaluating the thermal response of sprinkler heads was also carried out. The wind tunnel was adjusted to give air velocity of 1 ms⁻¹ or 3 ms⁻¹ and temperature at 90 °C. Sprinkler head was put in the work section either in parallel or perpendicular to the air flow direction. However, experimental data show that HCP is not able to shorten the sprinkler head activation time in the standard plunge test. Results suggest that the plunge test is not appropriate for studying the thermal sensitivity of sprinkler heads with HCP. This is because the HCP will change the physical environment assumed in the plunge test.