Occupant tenability in large-scale residential fires: an analysis of heat exposure, toxic gases, water application, and fire-service ventilation

Residential fires;Tenability;Toxic gases;Laser diagnostics

Traina, Nicholas A

关键词: Residential fires;    Tenability;    Toxic gases;    Laser diagnostics;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/98370/TRAINA-DISSERTATION-2017.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

The fire dynamics of residential fires has been drastically changing in the past 50 years. Modern fires burn faster and produce more toxic gases due to the increased presence of synthetic materials and plastics in the fire environment. In order to gain a better understanding of the risks present in modern residential fires and the effect of modern firefighting tactics on the fire environment, several large scale experimental studies were undertaken. These studies aimed to analyze the threat of heat (radiative and convective) and toxic gases (carbon monoxide, carbon dioxide, and hydrogen cyanide) on occupants in the fire environments. The large-scale experiments also studied the influence of different firefighting ventilation and water application techniques.The first large-scale study aimed to study vertical ventilation and transitional water application tactics. This study also allowed for quantification of the heat and toxic gases threat based on the ISO 13571 methodology. Seventeen experiments were performed at Underwriters Laboratories in Northbrook, IL, with nine experiments in a one-story structure and eight experiments in a two-story structure. Different types of fires were studied in both structure types, including living room fires, bedroom fires, and kitchen fires. Some of the major findings of the study were that toxic gases pose a much more significant threat in the one-story structure than does heat exposure. However, the threat from heat and toxic gases is similar in the two-story structure fires. Additionally, it was observed that ventilation actually resulted in rapidly deteriorating conditions and, if possible, firefighting crews should aim to get access to the fire environment with as little ventilation as possible.The second large-scale study looked to study the impact of exterior and interior water applications on the fire environment. This study implemented an experimental setup involving pig skin as a surrogate for human skin. The pig skin specimens were used to analyze the impact of water application on possible steam burns for trapped occupants. Additionally, a tunable diode laser absorption spectroscopic technique was employed to measure water vapor in the fire environment. Twenty-four experiments were performed in identical one-story structures with ignition occurring in the bedroom(s) at Underwriters Laboratories in Northbrook, IL. It was observed that water application resulted in spikes in skin surface temperatures. However, there was no significant difference observed in temperature spikes between interior and exterior applications. And the impact of delayed intervention resulted in much larger skin temperatures than the spikes observed from water application, suggesting it is best to get water on the fire as soon as possible. The laser diagnostic technique was successfully implemented, although the amount of obscuration was so large that at times signal was lost. Therefore, a three-tier sensitivity scheme was developed and tested at the Illinois Fire Service Institute that could measure water vapor over transmission ranges from 0.01-100% transmission.Finally, a laser diagnostic technique was developed and tested at the Illinois Fire Service Institute that could measure Hydrogen Cyanide in the fire environment. The measurement scheme extracted gas samples from the fire environment and passed the sample through two filters to filter out the soot. Hydrogen cyanide absorption was measured using a tunable laser near 3001.5 nm, and the scheme could measure HCN at a rate of 10 Hz with a detection limit of 3.6 ppm-m. The measurements showed that the threat from hydrogen cyanide can be equal to or greater than the threat of carbon monoxide poisoning, especially at greater heights in the fire environment where more than 1000 ppm HCN was measured during one experiment at 1.2 m above the floor.