Defining the specific formation coefficient and the critical partial density of hydrogen cyanide and carbon monoxide at the fire indoors

Introduction. Modern mathematical models of the distribution of toxic gases use the values of specific coefficients of formation of only three gases. It is not considered the whole spectrum of toxic gases produced during the combustion of synthetic materials. Therefore, the experimental study of the process of hydrogen cyanide formation is an important task. Aims and purposes. The purpose of this article is to develop a methodology for obtaining initial data on the release of hydrogen cyanide. These data are necessary to calculate the time of blocking evacuation ways. To achieve it, the value of the critical concentration of hydrogen cyanide was justified. The experimental unit was modernized and experimental studies of partial densities of hydrogen cyanide and carbon monoxide, as well as specific coefficients of their release, were carried out during combustion of modern cable products. Methods. An experimental method is used to study the process of formation of hydrogen cyanide and carbon mono¬xide during the combustion of samples of cable products in a modernized small-size experimental unit. The results were analyzed. Results. The critical value of the partial density of hydrogen cyanide, presented in normative documents, on the basis of analysis of data given in the literature sources, is substantiated. Experimental dependences between the time of testing and partial densities of hydrogen cyanide and carbon monoxide, as well as their specific coefficients of release, were obtained. This study reveals that the experimental value of the partial density of hydrogen cyanide reaches a critical value. That fact justifies the need to calculate the time of blocking the escape routes with con-sidering influence of hydrogen cyanide. Conclusion. The modernization of the experimental unit makes it possible to obtain experimental dependencies on the time of partial densities of hydrogen cyanide and carbon monoxide, as well as specific coefficients of their separation. This makes it possible to update (by HCN and CO) the existing database of typical fire load and to calculate the time of blocking the escape routes in case of combined effects of the above mentioned gases. When calculating fire risks in case of the burning of modern cable products, it is necessary to determine the time of blocking evacuation routes by hydrogen cyanide.