Evaluating Effects of Heat Fluxes and Duration on Performance of Firefighters’ Protective Clothing Using Destructive and Non Destructive Methods
Date
2020-07-06
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0000-0001-8588-5319
Type
Thesis
Degree Level
Masters
Abstract
Firefighters rely on their protective clothing to provide them with maximum protection while carrying out their duties. New pieces of firefighters’ protective clothing are constructed to meet various standards and regulations. However, degradation will occur over time due to a number of factors. As most textile tests are destructive, non-destructive test methods are needed to monitor degradation levels and provide useful data for determining the time to retirement especially given the high replacement cost of firefighters’ protective clothing. The focus of this study was thermal ageing of outer shell fabrics due to high heat fluxes including the effect of the duration of exposure. Tensile strength of three Kevlar/Polybenzimidazole (PBI) outer shell fabrics was measured before and after exposures to heat fluxes of 10 to 40 kW/m2 in the cone calorimeter for 30, 60, 90, 120, and 300s durations. Fabrics exposed to a low heat flux of 10 kW/m2 did not show significant change in the tensile strength. For higher exposure levels of 20 to 40 kW/m2, the fabric strength fell below standard requirements (i.e. less than 623N) for the RS Black and RS Natural fabrics while the remaining strength for SCI PBI Max fabrics stayed above 623N up until the 40kW/m2 heat flux exposure.
The reflectance and transmittance properties of fabrics were measured using near infrared (NIR) spectroscopy and correlations with the remaining tensile strength of the fabrics were developed. Changes in the NIR spectrum over the 800-2000 nm wavelength range along with fabric temperature measurements, thermogravimetric analysis and optical microscopy were used to examine the effects of heat flux and duration of exposure on performance of these fabrics. Methods of analyzing NIR data, used in the group’s previous research were evaluated: percentage shift in absorbance, absorbance feature characteristic changes (area and prominence) and slope change based on a normalized difference index method. Results from the normalized difference index slope change method showed a consistent relation to the original tensile strength for all three types of fabric investigated. Finally, it is expected that results from this research will be used for developing practical devices for non-destructive evaluations of firefighters’ protective clothing.
Description
Keywords
Firefighters, protective clothing, non-destructive testing, near infrared spectroscopy, tensile strength testing, aging
Citation
Degree
Master of Science (M.Sc.)
Department
Mechanical Engineering
Program
Mechanical Engineering