Introduction. Fires that occur when gas explosions occur in residential areas exacerbate an already dangerous ­situation, but they do not always happen. This allows us to hope for the possibility of reducing fire risks in gas explosions by conducting research and developing measures for this.

The task of the research is defined as the study of the conditions under which fires occur in the case of gas explo­sions in the room. The process of interaction of gases and combustible materials is characterized by short-term ­explosion and heating of combustible materials with a lack of oxygen. Presumably, the conditions for the ignition of combustible materials are their low heat capacity, the location of the position in the volume and the flow of ex­ternal air into the chamber.

Methods and means of research. The research was carried out experimentally on a 10 m³ cubic chamber filled with propane-air mixture. The explosion pressure was recorded and video was recorded outside and inside the chamber. To assess the level of flame impact on the combustible material, the developed indicators of heat flows with a sensitive element in the form of paper were used. There were 24 indicators inside the chamber.

Research result and discussion. It was found that less fire-dangerous places, where the thermal impulse was no more than 500 kJ/m², were the corners of the chamber and its wall areas, excluding the upper wall, and more ­fire-dangerous was the volume from the center up to the window opening along its entire width, where the thermal impulse was 600 kJ/m² or more. There were no visible traces of coking in the places where the paper and wire were glued together. The paper, which was in a fire-hazardous area, ignited when the outside air came in after the explosion.

Assumptions about the conditions of fire in a gas explosion in the room were confirmed: the risk of fire depends on the heat capacity of the combustible materials, their position in the volume and the flow of external air into the chamber after the explosion.

Introduction. In order to calculate the time for blocking escape routes by loss of visibility, the value of the smoke ­generation coefficient, which is determined in a small-scale experimental installation, is critical. However, the parameters of the smoke formation process depend on a variety of factors whose influence has not been sufficiently studied. Therefore, scientific justification of test conditions for determination of specific smoke formation factor is necessary. 

Aims and purposes. The aim of this work is to study the influence of conditions in the combustion chamber on the smoke generating ability of wood. To achieve this aim: a modification of the existing experimental installa­tion was performed, which allowed determining the optical density of smoke inside the exposure chamber; experi­mental studies of burning of wood were carried out, during which the optical density of the smoke was measured on the different distances between the electric heating emitter in the combustion chamber of the installation and the surface of the sample of the material under study.

Methods. Measurements of temperature and heat flux density inside the combustion chamber were carried out at different distances from the electric radiator, using certified equipment in a conditionally sealed volume of the experimental installation.

Results. The experiments showed that the specific smoke generation coefficient significantly depends on the test conditions in the combustion chamber. The smoke generation coefficient obtained at the modified installation ­during the burning of coniferous wood varies within 22.1–56.9 Np·m²/kg in the combustion mode and 82.9–134.5 Np·m²/kg in the smoldering mode. For coniferous wood materials, the value of this coefficient used in modeling fires is 57–61 Np·m²/kg, which is comparable with the range of its changes in the experiments. The va­lues of the smoke generation coefficient obtained at the standard installation GOST 12.1.044–2018 significantly exceed the values of the above coefficient obtained at the developed installation. The difference in smoke generation coefficients obtained by the proposed method and the standard method exceeded 233.1 Np·m²/kg in the combustion mode and 640.5 Np·m²/kg in the smoldering mode.

Conclusion. The design features of the experimental installation and the test conditions, significantly change the conditions in the combustion chamber. This fact has a strong effect on the specific smoke generation coeffi­cient of the combustible material. Therefore, in order to calculate reliably the time of blocking evacuation routes due to loss of visibility, further investigations are necessary to substantiate scientifically the method for determin­ing the above mentioned coefficient.

Introduction. Wide application for the arrangement of passenger railcars (curtains, upholstery and covers of chairs and sofas, bedding) is occupied by fabrics made of fire-proof, chemically modified polyester fibers that meet ­foreign requirements. An experimental study of the parameters of fire hazard of such a fire-resistant textiles ac­cording to the Russian requirements to furnish railcars showed the impossibility of achieving normative criteria on the toxicity of combustion products and smoke-forming ability because of the peculiarities of the process of ­thermal decomposition. Therefore, an important task is to conduct a comprehensive research on the feasibility of establishing realistic numerical values of criteria of toxicity of products of combustion and smoke generation.

Problem of the issue. A feature of the thermal decomposition of polyethylene terephthalate (PET) is its ability to be in a viscous state at high temperatures. The most effective method of fire protection of PET fibers is chemical modification at the stage of their production due to the introduction of organophosphorus functional compounds in the synthesis process. Wide application in the construction of railcars, flameproof tissue is significantly hampered by their failure to comply with the requirements for smoke generation ability and toxicity index of combustion ­products.

Results and discussion. Introduction in the polymer chain of PET retardants that do not affect the conditions of tech­nological processing, possibly with their contents not more than 10 % by mass. This amount of flame re­tardant provides the material’s resistance to ignition and flame spread on the surface, lack of education burning melt, but does not alter significantly the toxicity index of combustion products and the rate of smoke generation. Experimental data on the toxicity of combustion products (the yield of CO and CO₂ in the mode of flaming combus­tion) flame retardant, low flame on the surface of the fabrics, flameproof polyester fibres. A comparison of the results of determination of toxicity index of products of combustion to the results of calculations of the generalized index of toxicity (CIT_g).

Conclusions. The criterion value of CIT_g (0.75) was established for evaluating the possibility of using textile materials in railway sleeping railcars, corresponding to the index of toxicity of combustion products from 34 to 52 mg/m³ (43 mg/m³ ± 20 %), which indicates the possibility of using fabrics with the index of toxicity of combustion products HCl₅₀ ≥ 35 mg/m³. Proposals have been developed to improve fire safety requirements for textile materials used in passenger railcars.

Introduction. Many materials are subject to flameless, smoldering combustion: coal, cotton, peat, carbonizing ­polymers, etc. The fire hazard of smoldering burning of organic materials is that low-calorie ignition sources are sufficient to initiate the combustion process, the process is hidden, making it difficult to detect, and can spontaneously turn into a fiery one.

Purpose and objectives. The purpose of this work was to determine the macrokinetics of pyrolysis and thermo­oxidative decomposition of wood of different types of conifers and deciduous species by thermal analysis.

Methods. Samples were investigated by thermal analysis in an inert and air environment. For this, we used the automated modular system Du Pont-9900, including the TGA-951 thermobalance, and the DSK-910 diffe­rential scanning calorimeter.

Results. It was found that the pyrolysis of the main components of wood (hemicellulose and cellulose) proceeds according to the nucleation and growth mechanism of nuclei according to the case law R (n = 1) with activa­tion energies close in order of magnitude for different species (98–136 kJ/mol for hemicelluloses and 203–233 kJ/mol for cellulose). At the stages of thermooxidative decomposition of wood components and heterogeneous oxidation of the carbonized product, diffusion of the D3 (D4) type in spherical geometry becomes the mechanism controlling the process. The effective activation energy of the decomposition of hemicelluloses is reduced to 90.9–95.8 kJ/mol, and of cellulose to 138.3–160.9 kJ/mol. The reaction of heterogeneous oxidation of carbonized products makes a significant contribution to the flameless, smoldering combustion of the material. It is diffusion-controlled and is characterized by high values of activation energy (up to 285 kJ/mol).

Conclusion. The results of the work make it possible to evaluate the macrokinetic parameters of pyrolysis and thermooxidative decomposition of wood of different species during flameless combustion. The obtained data can be used as the main parameters for modeling the heterogeneous combustion of wood of different species in buildings.

Introduction. The aim of the research was to study the effect of carbon nanostructures – astralenes on the opera­tional characteristics of flame retardant intumescent compositions (FRIC), as well as to establish the relationship between the flame retardant efficacy of modified intumescent coatings on their thermal stability, adhesive strength and electrophysical properties.

Materials and research methods. The flame retardant intumescent composition “Thermobarrier” 2 based on ­epoxy resins with astralenes under conditions of electrophysical modification was used as an object of study. The experimental part includes the study by the method of synchronous thermal analysis, the measurement of ­dielectric permittivity, the determination of adhesion by the separation method, the interconnection of the pro­perties of FRIC from the modification conditions by the method of neural network modeling, the determination of the fire retardant efficiency of coatings in the conditions of hydrocarbon flaring.

Research results. FRIC with astralenes at a concentration of 0.1 % by vol. modified under the influence of an alternating low-frequency field has improved operational characteristics: the time when the limit temperature of the surface to be protected increased from 65 to 96 minutes, the adhesive strength increased by 38 %, the oxygen index increased by 11 % compared to the base composition. At the same time, exothermic peaks in the tempera­ture range of 550–700 °C shifted to the domain of larger values by 85 °C, in comparison to the basic composi­tion. Under electrophysical exposure, a regular arrangement of astralenes in the material occurs, as evidenced by a decrease in the dielectric constant of the coating by 45 %, in comparison to an unmodified composition.

Conclusions. Modification of the flame retardant with astralenes leads to an increase in fire retardant efficiency, adhesive strength, thermal stability, a decrease in the flammability and permittivity of the FRIC, provided that the astralenes are uniformly distributed in the coating at a concentration of 0.1 % by vol. The results of neural net­work ­modeling permit to make a conclusion that the physicochemical mechanism of increasing the operational characteristics of FRIC with astralenes introduction and electrophysical effects is associated with the uniform distri­bution of carbon nanostructures in the polymer matrix, a decrease in combustibility with an increase in the adhesive strength of the coating. The data of the research results reflect the possibility of using astralenes as a component of the formulations to increase the operational characteristics of FRIC based on epoxy resins under the conditions of flaring hydrocarbons combustion.

Introduction. Compliance with fire safety standards and rules in dormitories of educational institutions requires responsible management and a high level of student awareness. Residents of hostels should know the rules of conduct in case of fire. Such facilities are potentially sources of increased risk of fire. To prevent them, it is necessary to study the state of fire safety and identify problematic issues in its provision.

Aims and purposes. Based on a review of analogues, the need was identified to improve the safety culture among students. The results obtained are confirmed during the study. Student safety culture directly affects the fire risk. The relevance of the study lies in the need to take measures to increase the knowledge and skills of students ­about measures to prevent fires. To solve this problem, it is necessary to improve the fire safety management of dormitories.

Methods. The use of modern methods for determining students’ awareness of fire safety, as well as training and monitoring methods on this issue will reduce the fire risk of such objects. To determine the level of students’ awareness, testing was used, as a result of which problematic issues were identified.

Results and discussion. According to the results of the study, a weak knowledge of students about the basics of fire safety was revealed. Based on the results of the study, recommendations and suggestions for improving ­training and control are given. All recommendations have a direct impact on ensuring fire safety in the hostel.

Conclusion. It is necessary to develop students’ awareness of fire safety in order to reduce fire risk in dormitories, using briefings, trainings, periodic exercises, etc.

The article provides information on the “cost” of fires (losses from fires and the cost of fighting fires) in different ­countries of the world at the beginning of the XXI century. The presented assessment of the “cost” of fires (direct losses from fires, indirect losses, fire services expenditures, the cost of fire protection systems of buildings and the cost of fire insurance administration) was obtained based on an analysis of data from the World Fire Statistics Center (WFSC) for the period 1981–2011. It is shown that on average, direct losses from fires for all countries is estimated at 0.21 % of the Gross Domestic Product (GDP), indirect losses — 0.04 % (five times less than direct). The fire services expenditures is 0.16 % of GDP, fire protection of buildings — 0.28 % and cost of insurance administration — 0.11 %. In general, for 20 developed countries fire losses account for 0.25 % of GDP, the cost of fight­ing them is 0.57 % of GDP, i. e. costs are more than three times the losses. On average, the “cost” of fires in these 20 countries is 0.8 % of GDP. If we add to this the social losses associated with the fire deaths and fire injuries, the costs of research, training for the fire department, etc., then the “cost” of fires will be about 1–2 % of GDP. The presented estimate of the “cost” of fires in the United States based on reports from the National Fire Protec­tion Association (NFPA) of the United States. The data on the “costs” of fires of the WFSC and NFPA are compared. Quite reliable estimates of the “costs” of fires in the modern world have been obtained.

Technical solutions using active lightning rods operating on the principle of Early Streamer Emission (ESE) and ­device neutralization direct lightning strike (DAS/CTS) are presented. Studies of the effectiveness of the indicated lightning protection systems are considered. Features of the use of ESE and devices for protecting objects in ­thunderstorm conditions are indicated. The main results of the analysis of the operation of these devices on real objects are given. The inexpediency of using ESE and DAS/CTS devices instead of existing classic lightning rods is shown.