INCREASING THE VALIDITY OF EXPERIMENTAL DEFINITION OF SUBSTANCE AND MATERIAL TOXIC POTENCY

The analysis of thermogasdynamic conditions of experiments to define the toxicity level of combustion products in case of a closed fire have been conducted. The results of theoretical and experimental research of the amounts of toxic gases concentration (as the example of carbon monoxide) and the temperature in the mixtures of combustion products and air, which are formed in the small-scale experimental installation, and considerations on distribution possibility of the received results onto the real full-scale room are presented. Analytical solutions have been found to calculate the density of toxic gas in sealed small-scaled and large-scaled premises with small apertures or on the first stage of the fire, when there is only a replacement of the gas environment of the room outside through apertures. It is shown that the proportionality coefficient between the characteristic density of carbon monoxide and the relation of coefficient of evolving of carbon monoxide to the lowest working warmth of combustion does not depend on the properties of the combustible material, the sizes of the room and the area of the open surface of the combustible. It is only the function of three parameters characterizing the thermodynamic picture of the fire — medium-volume temperature of the gas environment, the coefficient of heatlosses and air temperature. The experimental small-scaled installation for defining the indicator of toxicity consists of the combustion chamber, the exposition camera, electro-heating radiator, the fan and the holder of a sample. For continuous control of the structure of the air-gas environment in the exposition camera gas analyzers of carbon oxide, carbon dioxide and oxygen dioxide are used. For continuous temperature control in the exposition camera nine thermoelectric converters were used. The tests in flame burning conditions of solid combustible loading (isolation of a power cable) and liquefiable combustible loading (industrial oil) were carried out. Theoretical and experimental dependences on medium-volume temperature of the gas environment of medium-volume density of carbon oxide, and also the proportionality coefficients between the characteristic density of carbon monoxide and the relation of coefficient of evolving of carbon monoxide to the lowest working warmth of combustion for the considered schemes of thermogasdynamics of a fire are received. It is shown that in the standard small-scaled experimental installations the amounts of toxic gases and temperature concentrations, used in calculating the indicator of toxicity, are not medium-volume and they are measured in insufficient quantity of randomly located points in experimental volume. Thus, thermogasdynamic process in experimental volume is significantly non-stationary and inhomogeneous. Therefore, the researched data of the toxicity indicator cannot authentically characterize the toxic properties of combustion products. Standard small-scaled experimental installations are to be modernized because of the essential inhomogeneity of temperature and concentration fields to define reliably the medium-volume temperatures and concentration of toxic gases with the exit to steady-state conditions of the thermogasdynamic picture. The defining of the toxicity indicator on the small-scaled experimental installations according to the chemical analysis demands for the receiving the gas mixture, which is adequate to the corresponding mixture in the full-scaled premises, additional measurements of heatlosses coefficient from the gas environment of the experimental volume to its protecting constructions. The two main directions for further research work are defined: the improvement of the standard test method and the development of the scientific bases of designing the small-scaled flowing camera and the technique to carry out experiments in it.