Introduction. Emergency gas explosions occur at industrial facilities as well as in residential buildings. An analysis of normative documents in the field of explosion resistance of buildings and structures subject to an accidental gas explosion has been carried out which revealed a lack of requirements for their explosion resistance and methods of testing their resistance to a deflagration accidental explosion.

Objective. A team from the Institute of Comprehensive Construction Safety at the National Research Moscow State University of Civil Engineering (NRU MGSU) developed a test procedure for determining the resistance of prefabricated metal structures to a deflagration explosion of an air-gas mixture and conducted a study including two experiments and analysis of the results to determine the application of building envelopes in the field of explosion protection of buildings and structures against excessive pressure deflagration

Materials and methods. The researches have been carried out with the use of a test bench for light-load-bearing constructions according to GOST R 56289. Fabricated metal structures, consisting of 200-mm-thick wall sandwich-panels and metal frame of two steel pipes of 100-mm section were used as test specimens. In the course of the investigations, the failure of the locking joint of the panels and the complete failure of the enclosing structure were monitored.

Results and discussion. Studies have shown that with an overpressure of 17–18 kPa and the exposure time of blast load of at least 250 ms, a significant deformation of the structure with a residual deflection was observed. Complete destruction of the structure occurred at the intensity of the dynamic impact in a 45–47 kPa blast wave and the exposure time of the blast load about 400 ms.

Conclusions. It has been established that the prefabricated metal structure consisting of wall sandwich panels and a metal frame can be used as an explosion-proof protective fence at production facilities in the calculation of blast loads. Several variants of increasing resistance of the structure to deflagration explosion have been proposed.

Introduction. Sealed equipment (hereinafter referred to as hermetic chambers) is used in various branches of economy. Atmospheres enriched with oxygen (in some cases under variable pressure conditions) are used.
It was shown that the main reason of the fires in the pressurized chambers was the unregulated use of the electrical equipment, as well as combustible substances and materials on the basis of organic compounds included in the materials used in the pressurized chambers.

Objective. To find ways to decrease combustibility of materials used in pressurized chambers and to study fire risk parameters of pressurized chambers with high oxygen content and increased pressure.

Objectives. To determine the boundary conditions of applying materials with increased values of temperature, oxygen content and pressure and analyze the results of experimental studies of combustibility of materials used in sealed chambers.

Research methods. Investigation of the characteristics of the combustion process of non-metallic materials under increased pressure was carried out on an original setup represented by a stainless steel vessel with a height of 750 mm and an inner diameter of 155 mm. A spiral of nichrome wire was used to ignite the sample. The pressure was fixed with a manometer.

Results and their discussion. As a result of experimental research of fire hazard of construction and construction materials in oxygen-enriched media and under increased pressure the ways of increasing the oxygen concentration limit (OCL) and reduction of combustibility of materials were determined: application of heat-removing surface, incombustible shell; putting inhibitors in their composition and structure; surface treatment with different fire protective compositions and impregnations. When studying the parameters of fire hazard (flame propagation velocity, heat of combustion, autoignition temperature) of materials under the conditions of changes in the composition of nitrogen-oxygen atmosphere and pressure, it was found that the OCL for all materials decreases at higher pressures.

Conclusions. It is found that the limiting oxygen concentration depends on the geometrical dimensions of the sample, as well as on the speed of the gas flow. At higher pressures the OCL for all the materials decreases. The presence of a heat-removing surface also leads to higher OCL, which increases with increasing substrate thickness and decreasing thickness of the material on it. For materials not containing substances that inhibit the combustion reaction, a decrease in the LOC value with an increase in the number of hydrogen atoms in the polymer macromolecule is characteristic.

Introduction. To find out the influence of historical parquet floor on the safe evacuation of people in cultural heritage objects, it is necessary to carry out a mathematical modelling of fire hazard propagation with the initial parameters of the existing combustible load.

The purpose of the article is to consider the experimentally derived fire hazard characteristics of historical wood compared to the required values for flooring on evacuation routes and in museum halls. To compare the values of the smoke-developed index and the net heat of combustion with those available in the reference literature.

Materials and methods. To study the fire hazard characteristics of historical floor coverings, the dies of existing parquet floor with a service life of about 160 years in the halls of the Winter Palace at the State Hermitage Museum were selected as specimens. Experimental determinations of the indicators were carried out on the appropriate test equipment using standard methods.

Results and discussion. Analysis of the results of the research shows that the fire hazard characteristics of historical wood do not meet the legally established requirements for floor coverings in halls in terms of their smoke-forming capacity and flammability, and in corridors and foyer halls in terms of their smoke-forming capacity. The smoke-forming capacity values obtained experimentally differ from the reference values used to calculate the dynamics of the build-up of the DFF in the buildings of museums and exhibitions. In addition, the values of the net heat of combustion obtained in the study differ from those given in the reference literature.

Conclusions. An estimation of the results of the carried out research and the available indexes in the reference literature allows to assert necessity of carrying out of scientific experiments for definition of characteristics of fire hazard of wood of historical objects with the purpose of formation of the reference database of characteristics of fire hazard of materials, used in museums, located in palaces — objects of cultural heritage. The use of refined reference data will improve the accuracy of calculations of individual fire risk on historical objects.

Introduction. The reduction of flammability of gas-filled polymers prone to carbonization is based on the use of phosphorus- and boron-containing compounds that reduce the formation of combustible volatile pyrolysis products and increase the yield of coke residue. This reduces the rate of heat release, heat and mass transfer between the material and the flame. In the scientific literature the data about the influence of phosphorus-containing flame retardants on thermal stability, combustibility and smokeability of foams are given, but there are no data about the influence of phosphorus concentration on fire danger indicators of foams.

The aim of this paper is the development of effective methods of production of casting foams based on reactive oligomers with low fire hazard and high-performance. Objectives: to reveal the influence of phosphorus concentration on the technological and physical-mechanical characteristics, thermal resistance and fire hazard indices of foams and to develop fire-proof thermal insulation materials possessing high performance. 

Methods. Physical-mechanical properties and fire hazard indices of gas-filled polymers were determined according to current GOST. Thermal properties and composition of combustion products of foams have been studied with thermoanalytical complex DuPONT-9900 and chromatography-mass spectrometry.

Results and discussion. The concentration of phosphorus in the synthesis of rigid polyurethane foams with reduced flammability and high performance should exceed 2.1 % wt. The low-combustible urea foams have been obtained at a phosphorus concentration of 0.2–0.3 % wt. For the production of non-flammable, low-­flammable resin foams, the phosphorus concentration is 0.6–0.7 % wt. At the same time, organophosphorus flame retardants containing reactive groups are highly effective.

Conclusions. As a result of experimental studies the influence of phosphorus concentration and content of organophosphorus-containing flame retardants on physical-mechanical properties, thermal stability and fire hazard of foams based on reactive oligomers was revealed, the pouring foams with lowered fire hazard and high performance were developed.

Introduction. Space-planning solutions for underground stations have an effect on the comfort and safety of passengers. Mathematical modelling is a perspective method for solving problems dealing with the determination of adequacy of adopted space-planning solutions for stations depending on passenger traffic.

Aims and purposes. The purpose of the study is to justify the method of mathematical modelling of passenger flows to develop optimal space-planning solutions of interchange stations of underground. To achieve this goal, the following tasks were solved: the development of a model interchange station concept; modelling passenger flows with initial and optimized volume planning solutions; modelling of passenger evacuation from the station in case of fire in the basement of the arriving train’s central carriage.

Methods. The paper presents a method of mathematical modelling to justify the space-planning solutions of underground stations. The software package Pathfinder developed an individual flow model of the interchange station, which simulated the passenger flows with initial and optimized volume-planning solutions. The software package PyroSim was used to simulate the spread of fire hazards.

Results and discussion. Based on the results of mathematical modelling, the optimal space-planning solutions for underground stations were determined, on the basis of which the passenger evacuation scenario was performed. It is obtained that there are 3,684 passengers and 296 workers at the station when the evacuation begins. The simulation results showed that the total estimated evacuation time from a typical transfer station is 814 seconds. It is obtained that the values of dangerous fire factors in the calculated points do not reach critical values until the evacuation is completed.

Conclusions. A mathematical model of a typical interchange station has been developed and implemented to determine the optimal space-planning solutions and calculate the safe evacuation of people. On the basis of this study in the new edition of the Code of Practice 120.13330.2022 “Underground” made amendments that determine that the estimated number of passengers evacuating from the station in case of fire, is based on mathematical modelling of passenger traffic during the rush hour.

Introduction. Natural ventilation of ordinary staircases in case of fire is provided for by the provisions of regulatory documents in the field of fire safety and plays an essential role in ensuring the safety of people. This article analyzes the effectiveness of ventilation of staircases through window openings in the outer walls, as well as through the openings of exits to the roof.

The purpose of this article is to develop criteria and mathematical relationships for evaluating the effectiveness of technical solutions for ventilation of staircases, as well as their approbation for residential buildings of various heights.

Methods. Mathematical methods are used to predict the concentration of combustion products on different floors of stairwells, depending on the area of open window openings and the possibility of opening roof access hatches, as well as an analytical method for evaluating the effectiveness of technical solutions for ventilation of stairwells.

Results. Theoretical provisions have been developed to assess the effect of the area of open window openings and roof hatches on the natural ventilation of ordinary staircases in sectional-type residential buildings with exits from apartments to staircases, and calculations have been made to evaluate the effectiveness of these solutions in buildings of various heights.

Conclusions. Based on the research, criteria and mathematical ratios have been developed to evaluate the effectiveness of various technical solutions for the natural ventilation of ordinary staircases. At the same time, the effectiveness of these solutions is determined by the possibility of rescuing people from the apartments of the corresponding floor without the involvement of a significant number of firefighters and without the use
of personal respiratory and eye protection equipment.

Introduction. A high level of tension of physical and psychophysiological reserves of an organism which firefighters are exposed to probably contributes to the occurrence of erroneous actions and injuries. Occupational injuries are an indicator of the safety of activity, it cannot be excluded completely, injuries can only be minimized.

The purpose of this article is to carry out a qualitative assessment of the occupational risks of injuries and death of personnel, employees with special ranks, and workers of the Federal Firefighting Service (FFS) of the Emercom of Russia in federal districts and regions of Russia.

Methods. Over the 15 years (2006–2020) 3,758 injuries in the performance of official duties were recorded considering the personnel of the Federal Firefighting Service of the Ministry of Emergency Situations of Russia, 224 of them were fatal. The risk of occupational injuries was calculated per 10 thousand (10–4) people, the risk of death was calculated per 100 thousand (10–5). Optimal risk was considered to be those indicators that were 1/3 less than the average for the FFS of the EMERCOM of Russia, increased — more than 1/3, acceptable — with intermediate values.

Results and discussion. The average annual risk of occupational injuries of the personnel of the FFS of the EMERCOM
of Russia was (14.66 ± 2.01) ∙ 10–4 injuries/(person per   year). The optimal risk of injuries was in the Siberian Federal District and in 24 regions of Russia, increased — in the Far Eastern, North Caucasus Federal District and in 23 regions, acceptable — in other federal districts and regions. The average annual risk of death of the personnel of the FFS of the EMERCOM of Russia was (8.53 ± 1.00) ∙ 10–5 deaths/(person ∙ year). The optimal risk of death was in the Siberian Federal District and in 35 regions of Russia, elevated — in the North Caucasus Federal District and in 19 regions, acceptable — in other federal districts and regions.

Conclusions. It is necessary to take into account and analyze all cases of occupational injuries with the participation of chiefs, occupational safety specialists, engineers, firefighters and doctors in order to develop measures to prevent them.

Statistical data reflecting the state of the electric vehicle fleet in Russia are presented. The main characteristics of the battery packs of the most popular models of electric cars in the country are summarized. An analysis of existing measures to ensure safe operation of traction batteries, reducing the risk of their mechanical damage and therma.runaway is performed. The results of some foreign publications on combustion modelling and full-scale fire tests of electric vehicles in rooms and open spaces are reviewed. Recommendations for the development of necessary measures to organize fire-fighting with the participation of electric cars are given.