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COMMENT C H A E L E S W . B E C K E T T National Bureau of Standards 1) Upper bounds upon the quantity of energy released m thermal decomposition or combustion reactions give a measure of potential hazards. This can be calculated for many substances as discussed by Dr. Stull and also Dr Wall. Estimation of the concentration of toxic products is less accurate because the concentration may differ by very large amounts from the thermodynamic value [e.g. rapid quenching of nitrogen-oxygen mixtures from high temperatures yields nitrogen-oxygen m concentrations of several per cent much higher than the thermodynamic eqm- hbrium value (0 004% at 1000 K) ] Smce some decomposition products may be lethal in very low dosages, I would recommend caution m the use of thermodynamic estimates as a measure of potential toxic hazard. However, there are many ways m which thermodynamic methods can be apphed m fire research as in other fields of high temperature research and technology. 2) Apphed lanetic calculations now are possible for many high temperature processes usmg computer programs that mclude thermodynamic, kinetic, radiation, and some hydrodynamic processes. In some cases, these programs are bemg used m air pollution problems that are related to combustion. They can also be used in fire research where the same phenomena occur. 3) The current status of basic chemical kinetic data on substances containmg the elements H C N O is sufiBcient now to permit chemical kmetic modelmg of fire processes. This would mclude cellulose as mdicated by papers given m the recent symposium on the thermal decomposition and combustion of cellulose, American Chenucal Society Meetmg m Washmgton, September, 1971. 4) Data on substances contaimng halogens; fluorine, chlorine, and bromine probably is less extensive and reliable. A recent review by Creitz does include a fair amount of data related to flame inhibition by bromme and chlorme compounds. 5) Studies of the kmetics of gas phase oxidation reactions involvmg compounds of antimony, iron, molybdenum, and barium now are in progress. Although some of these studies are not directed toward fire research, they may contribute significant information. 6) I recommend that the fire research committee prepare a hst of substances (100 or less) that are most likely to be important in future work. This hst could then be sent to speciahsts m various fields who may be able to contribute relevant research on the properties of these substances. 277
