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Experimental and Modeling Study of Thermal Exposure of a Self-Contained Breathing Apparatus (SCBA)

Published

Author(s)

Michelle K. Donnelly, Jiann C. Yang

Abstract

An experimental apparatus designed to study firefighter turnout gears exposed to a thermal environment was developed. The apparatus consisted of an elevated temperature flow loop with the ability to heat the air stream up to 200 ºC. The thermal and flow conditions at the test section were characterized using thermocouples and bi-directional probes. The turnout gear used in this study was a self-contained breathing apparatus (SCBA). A mannequin headform with a SCBA facepiece and air cylinder coupled with a breathing simulator programmed with a prescribed breathing pattern was placed in the test section of the flow loop for the thermal exposure experiments. Three air stream temperatures, 100 ºC, 150 ºC, and 200 ºC, were used with the average air speed at the test section set at 1.4 m/s and thermal exposure durations up to 1200 s. Measurements were made using type-K bare-bead thermocouples at the mannequin’s mouth and the outer SCBA cylinder surface. The experimental results indicated that increasing the thermal exposure severity and duration increased the breathing air temperatures supplied by the SCBA. Temperatures of breathing air from the SCBA cylinder in excess of 60 ºC were observed over the course of the thermal exposure conditions used in most of the experiments. A transient mathematical model for heat transfer was developed to complement the thermal exposure experimental study. The model took into consideration forced convective heat transfer, quasi-steady heat conduction through the composite layers of the SCBA cylinder wall, the breathing pattern and the action of the breathing simulator and predicted the air temperatures from the thermally exposed SCBA cylinder and the temperatures at the outer surface of the SCBA cylinder. Model predictions agreed reasonably well with the experimental measurements.
Citation
Journal of the International Society for Burn Injuries

Keywords

Breathing Pattern, Experiments, Modeling, SCBA, Thermal Exposure, Thermal Injury

Citation

Donnelly, M. and Yang, J. (2015), Experimental and Modeling Study of Thermal Exposure of a Self-Contained Breathing Apparatus (SCBA), Journal of the International Society for Burn Injuries, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=915557 (Accessed April 20, 2024)
Created June 10, 2015, Updated February 19, 2017