Under the auspices of the NFPA Fire Protection Research Foundation and in conjunction with the UMCP Fire Protection Engineering Department and the Maryland Fire and Rescue Institute a research study was recently completed regarding the “Evaluation of Fire Service Training Fires.”
This study identifies the parameters that influence the development of thermal conditions during live fire training evolutions within burn facilities. As part of a previous study, tests were conducted on the third floor of the live fire training building at the Maryland Fire and Rescue Institute (MFRI). The principal measurements obtained during the training evolutions were temperatures and heat flux in the burn room. A model replicating the tests conducted in the MFRI training facility was created using CFAST version 6 and a validation was performed by comparing temperature and heat flux measurements from the test to the model’s estimation. Then, the MFRI CFAST model was used to simulate twenty one scenarios that examine the effects various fuel packages, ventilation strategies, room sizes, and time between sequential burn evolutions have on the thermal conditions inside a firefighter training burn room.
There are many fuel packages commonly burned during live-fire training. This study was only able to analyze fuel packages in which there is heat release rate data available, which include: stacked pallets, triangular pallets and excelsior, excelsior pile, flat pallets & excelsior, and upright pallets & excelsior (see Table 8 for more details regarding the fuel packages). Results show that of the fuel packages analyzed, the ones configured vertically (stacked pallets and the upright pallets and excelsior) have the greatest heat release rate and create the most severe thermal conditions, while triangular configured fuel packages create moderate thermal conditions and lastly, horizontally configured fuel package (flat pallets and excelsior) create the least severe thermal conditions. Horizontal ventilation causes a quick decrease in thermal conditions, while leaving remote vents open during a burn evolution limits the development of thermal conditions within the burn room. According to the model simulations where the same fuel package is burned in rooms that vary in size, the burn evolutions that occur in small rooms produce hotter conditions than ones that occur in larger burn rooms.
Also, as multiple sequential burn evolutions occur over the course of training, the initial ambient temperatures inside the facility continually rise to yield thermal conditions that are even more severe than the previous evolution. When minimal time is taken between burn evolutions, conditions can become very severe after multiple evolutions. Taking more time between burn evolutions can allow the facility to cool down and reduce the severity of thermal conditions. Based on the results of this simple study, it is recommended that NFPA 1403 be modified to include a hazard assessment procedure that can enable fire instructors to properly account for the principal factors affecting the severity of the thermal conditions produced in burn evolutions.
Download this document HERE as a PDF.
