North Carolina State University (NC State) researchers found that four new designs for shelters to protect firefighters trapped in wildfires could increase the survival time inside the shelter compared with the current industry standard. In lab simulations of wildfire burn-overs—where a wildfire sweeps over a group of trapped firefighters or equipment—temperatures inside the shelters remained within survival limits for longer, and the shelters took longer to break open.
Researchers hope their findings from the lab, as well as from field tests conducted across North America, could spur the development of new, better shelters. In addition, they hope the findings will inform new standards for shelter design and testing.
“For the wildland firefighter, deploying a shelter is the last thing they want to do; it’s the final resort, the last line of defense,” said study co-author Roger Barker, the Burlington Distinguished Professor of Textile Technology at NC State and the director of the Textile Protection and Comfort Center (TPACC). “While there’s no such thing as ‘fire-proof,’ what we’re trying to do is to buy more time. We were able to demonstrate our shelters could increase the time to failure—time that could be critical for survival.”
One problem with the industry standard shelter is that the aluminum outer layer will melt in contact with direct flame. “In light of the failure mechanisms of shelters that we observed during wildland fires, we thought we could develop better shelters that provide enhanced protection by incorporating an inner heat-blocking barrier and additional thermal insulation into the construction,” said the study’s lead author Joseph Roise, professor of forestry and environmental resources at NC State. “We know we can make a better shelter.”
With that goal in mind, the researchers designed two leading prototypes and two lighter versions weighing less than 5 pounds. They added insulating materials and experimented with different seam designs to keep them from falling apart.
In the TPACC lab, researchers tested the designs against the industry standard in a test chamber called the PyroDome Turbulent Flame Fire Shelter Test System. All of the prototypes had improved survival metrics compared to the standard, which reached the survival limit in less than 40 seconds. The researchers also tested the shelters’ performance in a variety of conditions in controlled burns in Canada, California, North Carolina and South Dakota. However, they found the field tests were not reliable enough to draw statistically significant conclusions because of wind, fuel and fire conditions.
The new findings could give manufacturers and people developing these shelters a new target to shoot for in terms of how to test them and minimal performance requirements, according to Barker.
The study, “Field and full-scale laboratory testing of prototype wildland fire shelters,” was published online in the International Journal of Wildland Fire. In addition to Barker and Roise, other authors include John Williams, a former research assistant in forestry and environmental resources at NC State, and John Morton-Aslanis, a research assistant in TPACC. The study was funded by the DHS FEMA Assistance to Firefighters Grant Program.