Comments on "Correction Factors for the Heat of Combustion in NFPA 72 Appendix B".
Comments on "Correction Factors for the Heat of
Combustion in NFPA 72 Appendix B".
Davis, W. D.
Fire Protection Engineering, No. 4, 46-48, Fall 1999.
ceiling jets; fire models; experiments; heat detection;
heat of combustion; NFPA 72
I want to express some reservations concerning the
revision to NFPA 72 Appendix B that is being considered
based on an article by Christopher E. Marrion in Fire
Protection Engineering. The rationale for this revision
is based on a paper published by Heskestad and
Delichatsios in which the correlation (H&D) used in NPPA
72 Appendix B was modified due to an updated measurement
for the heat of combustion of sugar pine. The revision
is substantial in that the heat of combustion for sugar
pine is reduced by a factor of 1.67 which significantly
changes the relationship between convective heat release
rate and excess temperature at the ceiling. Changes
such as theses, which substantially impact the way fire
protection engineers perform detector placement
analysis, should be verified using independent
supporting experiments in order to avoid dependence on a
single investigation. Heskestad and Delichatsios were
very careful in their original paper to compare their
measurements with existing experimental data in order to
verify that the results were supported with comparable
experiments. In their revision, when the heat of
combustion was changed, no comparison was made to the
results of other experiments.