ОПРЕДЕЛЕНИЕ УДЕЛЬНОГО КОЭФФИЦИЕНТА ОБРАЗОВАНИЯ И КРИТИЧЕСКОЙ ПАРЦИАЛЬНОЙ ПЛОТНОСТИ ЦИАНОВОДОРОДА И МОНОКСИДА УГЛЕРОДА ПРИ ПОЖАРЕ В ПОМЕЩЕНИИ

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 monoxide 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 considering 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.Введение. Современные математические модели распространения токсичных газов используют значения удельных коэффициентов образования лишь трех газов, не рассматривая весь спектр токсичных газов, образующихся при горении синтетических материалов, поэтому экспериментальное исследование процесса образования циановодорода представляет собой актуальную задачу. Цель и задачи. Целью статьи является разработка методики получения исходных данных по выделению циановодорода, необходимых для расчета времени блокирования путей эвакуации. Для ее достижения была обоснована величина критической концентрации циановодорода, модернизирована экспериментальная установка и проведены экспериментальные исследования парциальных плотностей циановодорода и моноксида углерода, а также удельных коэффициентов их выделения при горении современной кабельной продукции. Методы. Используется экспериментальный метод исследования процесса образования циановодорода и моноксида углерода при горении образцов кабельной продукции в модернизированной малогабаритной экспериментальной установке. Проведен анализ полученных результатов. Результаты. Обоснована критическая величина парциальной плотности циановодорода, представленная в нормативных документах, на основе анализа данных, приведенных в литературных источниках. Получены экспериментальные зависимости парциальных плотностей циановодорода и моноксида углерода, а также удельных коэффициентов их выделения от времени проведения испытаний. Показано, что в экспериментах парциальная плотность циановодорода достигает своего критического значения, что обосновывает необходимость расчета времени блокирования путей эвакуации с учетом циановодорода. Заключение. Модернизация экспериментальной установки дает возможность получить экспериментальные зависимости парциальных плотностей циановодорода и моноксида углерода, а также удельных коэффициентов их выделения от времени. Это позволяет актуализировать (по HCN и СО) существующую базу данных типовой пожарной нагрузки и проводить расчет времени блокирования путей эвакуации при совместном воздействии вышеуказанных газов. При расчете пожарных рисков в случае горения современной кабельной продукции необходимо определять время блокирования путей эвакуации циановодородом

Calculation of the critical times of carbon monoxide influence on humans in case of fire in the premises

A mathematical model of calculating the content of carboxyhaemoglobin in the blood of humans exposed to CO has been proposed. Results of comparing the calculation of carboxyhaemoglobin content with the experimental data of human exposure to constant concentration of CO during quiet breathing have been obtained. Results of numerical experiments for determining carboxyhaemoglobin concentration in case of rapid pulmonary ventilation that is characteristic for fire conditions in a room have been shown. The estimates of intervals of CO influence on the human body have been obtained with the use of the analytic solution of the integral model for calculating thermogasdynamics of fire. Critical fire durations obtained with the use of the proposed model and the traditional approach have been compared. It has been shown that the method of calculating the critical fire duration in terms of CO that exists in the scientific and regulatory literature on fire safety can lead to qualitatively and quantitatively incorrect results. © 2017 International Information Institute

Calculation of the critical times of carbon monoxide influence on humans in case of fire in the premises

A mathematical model of calculating the content of carboxyhaemoglobin in the blood of humans exposed to CO has been proposed. Results of comparing the calculation of carboxyhaemoglobin content with the experimental data of human exposure to constant concentration of CO during quiet breathing have been obtained. Results of numerical experiments for determining carboxyhaemoglobin concentration in case of rapid pulmonary ventilation that is characteristic for fire conditions in a room have been shown. The estimates of intervals of CO influence on the human body have been obtained with the use of the analytic solution of the integral model for calculating thermogasdynamics of fire. Critical fire durations obtained with the use of the proposed model and the traditional approach have been compared. It has been shown that the method of calculating the critical fire duration in terms of CO that exists in the scientific and regulatory literature on fire safety can lead to qualitatively and quantitatively incorrect results. © 2017 International Information Institute

Некоторые особенности определения показателя токсичности при стабилизированном горении жидкости в помещении

Analysis of thermal gas dynamic conditions of conducting experiments to determine toxicity of combustion products in case of fire in a room was carried out. Mathematic models to calculate options of heat and mass transfer in characteristic small-scale and large-scale rooms was considered.В статье приведены результаты анализа термогазодинамических условий проведения экспериментов по определению токсичности продуктов горения при пожаре в помещении. Рассмотрены математические модели расчета параметров тепломассообмена в характерных мелкомасштабных и крупномасштабных помещениях

Gas thermodynamic conditions of cold air entrainment by natural smoke exhaust system in case of compartment fire

Conditions of occurrence of abnormal operation of natural smoke exhaust system are analyzed when cold air is entrained into smoke exhaust windows preventing extraction of smoked heated gas layer beneath a ceiling (also known as plugholing). Analytical equation is derived for prediction of critical average volumetric temperature of gas layer beneath a ceiling when plugholing starts with consideration for the height of smoke exhaust window. This equation was compared with published experimental data and with numerical experiments using 3D field model of fire gas thermodynamics. It was found that the height of smoke exhaust window exerts significant influence on occurrence of plugholing and on maximum bulk flow rate of combustion products extracted from compartment via the window. © 2020, Institute of Advanced Scientific Research, Inc.. All rights reserved