Effect of Environmental Conditions on the Dehydration and Performance of Fire-Protective Gels

Abstract

During wildfire events fire-protective gels can be used as a line of defense to protect structures. The effectiveness of freshly applied gels in delaying ignition and flame growth on structures has been well established. However, in a real-world scenario there is a period between the application of the gel and the arrival of a spot fire or the fire-front. During this period, the gels are often exposed to extreme conditions consisting of high winds and low relative humidity. The effect of these weathering conditions on the performance of fire-protective gels is still poorly understood. This study examined the dehydration and performance of fire-protective gels following a range of weathering conditions. Two commercially available gels were applied to a 100-mm by 100-mm T1-11 plywood sample and then artificially weathered in an environmental chamber, with controlled temperature, relative humidity, and wind. The remaining mass of the gels was measured at selected intervals to determine the relationship between mass loss and dehydration related to weathering. A second series of tests was conducted on weathered T1-11 samples at specific mass loss states as well as on freshly applied gels using a 50 kW/m2 heat flux exposure utilizing a cone calorimeter. Results indicated that they dehydrated to the point where, after 3 h, fire performance was no better than the uncoated wood samples and the gels could facilitate ignition. This timeline suggests that gels should only be applied by first responders and homeowners should focus on evacuation related activities.