Thermal sensor performance and fire characterisation during short duration engulfment tests

Abstract

SummaryA small‐scale reproduction of the ISO 13506‐1 thermal manikin was constructed to enable the assessment of manikin sensor performance, the partitioning of energy, and the variability of the fire generated during short duration heat and flame engulfment tests. The cylindrical test apparatus simultaneously housed four total heat flux (THF) sensors, one radiant heat flux sensor, and three manikin sensors. Calibrated manikin sensors were provided by nine laboratories and were categorised as buried thermocouple, copper‐based, or surface‐mounted thermocouple sensors. The test apparatus was exposed to fire generated by four propane torches for three exposure durations. All sensors presented similar profiles in net heat flux over time, which could be divided into four distinct phases: transient increase, pseudo‐steady state, transient decrease, and post‐exposure. Over pseudo‐steady state, the mean THF over all exposure durations was 88 ± 8 kW/m2, and the ratio of convective to radiant energy was approximately 50:50, but highly variable. For a 4‐second exposure, manikin sensors from five laboratories had a bias in heat flux greater than ± 5% during pseudo‐steady state when compared with the THF sensors. This bias can primarily be attributed to the sensitivity of the manikin sensors to convective heat or heat loss due to sensor design.