SYMPOSIA PAPER Published: 29 September 2016
STP159320160023

Experimental Study of Heat Flux in Propane Flash Fires

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Existing test methods for determining of thermal protection from fire offered by textiles are typically characterized by the exposure of specimens to a controlled flame and measurement of energy transferred through the specimen. The measured energy transfer is then used to differentiate materials or further processing (burn injury prediction) is used as a basis for comparison. The test conditions are set by measuring the energy transferred to the sensor or sensors in absence of a test specimen. In order to represent a potential hazard and provide good differentiation among tested materials, an exposure heat flux is required that allows for rapid and substantial increase in the temperature of the tested specimen. A specified heat flux of 80–84 kW/m2 is common in both bench-scale and full-scale tests. Because of the use of controlled flame and significant energy transfer rates involved in these tests, there is a common misconception that these test methods constitute a simulation of a particular hazard, especially with regard to the hazard of hydrocarbon flash fires. In order to provide a basis for comparing specified test conditions with real-world hazard conditions, a series of heat flux measurements were performed on propane-fueled flash fires in open air. In each test, an array of heat flux sensors was positioned around a propane source. A large fuel cloud was allowed to form and subsequently ignited using a pilot flame. These experiments were carried out outdoors and as such were subject to prevailing wind currents. Because of the potentially high variability, more than 50 separate fuel releases were undertaken. The output of the array of sensors was used to determine the intensity and duration of each flash fire event. In addition to the array of heat flux sensors, an instrumented mannequin was constructed to measure the heat flux incident on a human form within the flash fire. The results indicate that there was significant variability in the conditions in each fire due to the open air conditions creating unpredictable distribution of fuel and air. Flash fires occurred that were less severe and more severe than the conditions used in standardized laboratory testing.

Author Information

Paskaluk, Stephen, A.
University of Alberta, Protective Clothing and Equipment Research Facility, Edmonton, CA
Ackerman, Mark, Y.
University of Alberta, Dept. of Mechanical Engineering, 10-203 Donadeo Innovation Centre for Engineering, Edmonton, CA
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Details
Developed by Committee: F23
Pages: 195–211
DOI: 10.1520/STP159320160023
ISBN-EB: 978-0-8031-7632-4
ISBN-13: 978-0-8031-7631-7