Researchers at North Carolina State University developed and evaluated a set of protocols that measure stored heat energy in turn out gear or stored heat burns, which often suffered by firefighters when they are not directly in contact with fire, said the study’s principal Dr. Roger Barker.
Barker is director of the university’s Textile Protection and Comfort Center (T-PACC). Researchers at the center evaluated the thermal performance of protective clothing worn by firefighters and focused specifically on stored heat burns. Stored heat burns are burns that happen outside a fire, where a fire’s thermal energy is absorbed by the materials that make up turnout gear.
“We wanted to develop a test method that would tell us more about the thermal threats that firefighters face when they’re not always directly exposed to a flame,” Baker said.
Barker and his team develop and evaluate a new test method for stored heat over two-phases. The first phase was sponsored by the National Institute for Occupational Safety and Health. During the phase, the team developed a laboratory testing method and tools to conduct the stored energy test, which measures transferred and discharged heat in turnout suit materials. When the materials are compressed against the firefighter, discharged energy can contribute to a burn. The study found the role moisture — mostly the sweat from firefighters — affected turnout materials and changed its heat capacity and thermal conductivity.
“In addition to that stored energy, heat continuously transmitted from the thermal environment through the materials and are impacted by the level of moisture in the fire suit would have in that would come, let’s say, from a sweating firefighter,” he said.
The second phase was sponsored by the National Fire Protection Research Foundation. Barker said it involved using that apparatus to test a variety of firefighter suits and to develop a database that will facilitate a new national standard that firefighter suits are measured against and certified.
“It examined the response to the protocols of a range of different materials, including outer shell fabrics, moisture barrier materials and thermal liners,” he said. “We wanted to provide it to the NFPA 1971 committee, which will consider establishing criteria around the test method.”
Barker said the NFPA is reviewing the protocols and will consider adopting this test method as part of requirements manufacturers must meet to have their suits certified as complying with the NFPA standard.
“We know there is no lab test that measures with absolute accuracy what a firefighter encounters, because every fire is a different set of conditions and thermal threats,” he said. “However, we now have a better understanding of the general causes and mechanisms behind transferred and stored heat, and a test method to measure these effects.”
