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An empirical relation has been developed which correlates and predicts the 6re-suppression effectiveness of a wide variety of gaseous, liquid and solid agents. The flame-extinguisbment model is based on the premise that extinction is dominated by heat-absorption processes and that a flame is extinguished when suBcient heat has been removed by the extinguishant to reduce the temperature to a limit value. This limit is the minimum temperature at which the effective rate of the combustion reactions is s d a e n t to maintain flamepropagation, and it depends in a predictable way on the properties of the suppressant and flame system. The heat-balance equation describing tbis is derived in two stages. In the first, a preliminary equation is obtained by considering only those substances which are thermally stable and act only as heat-capacity sinks. In the second, the equation is generalized by consideration of all endothermic reaction sinks, e.g. vaporization, dissociation and decomposition. The general equation correlates most of the extinction data found in the literature. The results suggest that for most substances the extinguishing capacity is related to heat-extraction and that many of the effects previously attributed to chemical mechanisms may be thermodynamic in nature rather than kinetic.

The system formaldehyde-ammonia has been re-examined. The results agree with those of Duden and Scharf, and designate cyclotrimethylenetriamine as the intermediate in the eventual formation of hexamine.2. The formaldehyde-ammonia solution prepared by Henry is found essentially to behave as cyclotrimethylenetriamine and not as trimethylolamine, which he suggested.3. The final stages of the hexamine synthesis from cyclotrimethylenetriamine are non-reversible in alkaline solution.

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Flame quenching by condensed or gaseous extinguishants and by external sources is examined. The quenching by extinguishants is due to heat-absorption sinks—dissociation, decomposition, vaporization, and heat capacity. External quenching by water-cooled metal surfaces or by radiation to surroundings is shown to have common properties with internal quenching by extinguishant particles or molecules.Flame-extinguishing mechanisms are effectively explained with thermal quenching concepts and a flame heat balance. New criteria for the extinguishment of Class B flames are postulated and, then, substantiated by a comprehensive analysis of extinguishment data for a large number of agents. Adiabatic limit temperatures were initially computed with the flame heat balance (Equation 1) using quenching quantities based on heats of formation of extinguishing substances at 298 K, but such limits and quenching quantities exhibited no systematic character. However, alternate limits and quenching quantities based on heats of formation of molecular parts (of extinguishing substances) exhibited exceptional ordering and internal consistency.This alternate analysis contributed to increased understanding of thermal mechanisms, concurrent exothermic reactions, and other processes involved in flame extinction. It is further demonstrated that the flame extinguishing effectiveness of dry chemicals and most gaseous halocarbons (agents containing C, H, F, CI, Br or I) can be reliably predicted from the additive properties of enthalpy, temperature, and quenching quantities. The flame-extinguishment model provides definitive criteria for selecting alternate agents with superior flame extinguishing properties.

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2‐Ethylhexanonitrile product: 2‐Ethylhexanonitrile reactant: 286 g. (2 moles) of 2‐ethylhexanamide product: palmitonitrile