Heat Release Rate Characterization of NFPA 1403 Compliant Training Fuels

Abstract

When using solid fuels for live fire training, NFPA 1403: Standard on Live Fire Training Evolutions requires that the materials be wood based. While the standard offers guidance on the type of fuels that are permissible for use in training, it offers little in the way of quantitative methods of selecting an appropriately sized fuel package. In order to examine the effects of fuel mass and orientation on heat release behavior, free burn heat release rate (HRR) experiments were conducted on twenty-one wood-based training fuel packages and twelve comparison furniture items. Training fuel packages demonstrated peak HRRs ranging from 1.0 MW to 3.6 MW, with the total energy release between 210 MJ and 1615 MJ. The furniture items exhibited peak HRRs between 0.9 MW and 3.7 MW, with the total energy release between 180 MJ and 995 MJ. A least-squares linear regression analysis indicated a good linear fit between total energy release and fuel mass burned among the training fuel packages (R2 = 0.98), suggesting that the effective heat of combustion is approximately constant at 14.2 MJ/kg. Generally, peak HRR increased as initial fuel mass increased, although the relationship was more variable, with the peak HRRs of similarly sized training fuel packages varying by nearly 1 MW. The results indicated that while total energy release was dependent largely on the initial fuel mass, peak HRR and peak burning duration were also dependent on the orientation and type of fuel in the fuel package. Wood-based training fuel packages were capable of producing peak HRRs comparable to individual items of furniture, although the total energy release was typically higher for the training fuel packages compared to corresponding furniture items.