How to Make Sure Wildfire Shelters Save Firefighters’ Lives

The fires burn quickly and unpredictably. Although firefighters receive extensive training to keep themselves safe, they sometimes get cut off by flames that can reach temperatures of over 2,000 degrees. Each person has a portable fire shelter that can be deployed to protect them from fire and hot gasses. There are serious limits to this technology and researchers are exploring new materials and designs.

Fire shelters have been used more than 200 times between 2006 and 2020, according to the National Wildfire Coordination Group. This last line of defense can be problematic. The Granite Mountain crew tragically died in the Yarnell Hill fire despite using their shelters. As fire seasons continue to grow more severe, the need for better shelters will only become more important.

According to an assistant professor of forest and rangeland stewardship at Colorado State University who was not involved in the recent fire shelter tests, the fire seasons are getting more severe. There was a fire that burned 6,000 acres in Colorado. It leads to more risk for firefighters. Firefighters are forced to retreat to their emergency shelters when flames spread quickly. Extreme fire events are when a lot of acres burn in a short time. There are factors that can cause fires to explode in a single day.

The only model approved for use by government-agency firefighters is the M2002, which folds down to a 4.3 pound packet. It is usually kept in a plastic sleeve and carried in a backpack. One person can lie down inside the half-tube that the packet can be unfolded into. The two-layer construction has an air gap between it and the insulation. The outer layer is made of silica woven that is laminated. The inner layer is made of fiberglass.

The existing fire shelter design should be retained. The organization always looks for improvement. Researchers at North Carolina State University are evaluating the M2002. The work was detailed in a report.

The lead author of the study is a professor at N.C. State. The domelike shape is great. The less heat you have on your body the closer you are to the ground. The emergency fire shelter prototypes focus on other ways to improve heat resistance because they are hard to beat. They are similar to the M2002 from the outside. An additional layer of heat- resistant material is added by some. The placement of the seams can be a weakness for others.

The N.C. state researchers built a fire chamber to test the fire shelters. The fire shelters were blasted with a direct flame. The set maximum temperature level for survivability in a shelter is 302 degrees F. The inside walls and seams were documented in a video camera.

Fire shelters have to be able to handle two types of heat. Think of it as warmth when standing by a fire. The outer layer of aluminum reflects most of the heat. He notes that aluminum is very durable, and when combined with asilica base, which slows the rate of heat transfer to lower the temperature inside the shelter, the materials work together well.

When a fire moves through a shelter deployment site and the flames or hot gasses directly touch the outside of the shelter, it's called convective heat. The outer layer is able to raise its temperature. The glues that bind the layers together can break as the temperature rises. The aluminum foil exterior can be torn away by wind if it is separated from the cloth of the shelter. convective heat can enter the shelter and quickly raise internal temperatures.

Fire shelters need to be tested in the field and in the laboratory because of the unpredictable conditions created by real wildfires. Eight field tests were conducted by the N.C. state researchers. The test sites offered a variety of fuel types, such as chaparral, where the ground is covered with shrubs or small trees, and grassland, where there are trees. Different flame configurations, temperatures and weather conditions were exposed to the prototypes. It was difficult to compare the M 2002 model with prototypes. Different fire behavior, inconsistent amounts of fuel, and high winds made for different conditions for each shelter.

There are many variables in a fire. It isn't predictable. David Maclay-Schulte is an equipment specialist at the U.S. Forest Service's National Technology and Development Program. It's difficult to get reliable data that way.

The M2002 and all four prototypes passed the fire protection tests, even in situations where flames penetrated the outer layer. The tests proved the effectiveness of the prototypes. According to Roise, all of the prototypes were better than the M2002 in the lab tests, and the one that performed best included a layer of heat resistant.

The prototype was larger and heavier than the current model. The shelter's weight as well as its cost are important factors. A shelter that adds too much to the burden of carrying 45 pound packs of equipment won't make the cut.

Toxicity was not tested by the N.C. State study. Increased protection from convective heating has been studied by researchers. Toxic fumes are released when these substances are exposed to high heat. According to Maclay-Schulte, firefighters can survive the fire, but they will suffer negative consequences.

The prototypes didn't dethrone the M2002 as the model firefighters carried into the field. The search for better fire shelters continues. Maclay-Schulte says that they test different materials to see if they react differently. There are always things happening with fire shelter development.