Introduction. It is necessary to update requirements for designing fire protection systems for these facilities in terms of the safe evacuation and rescue of children and personnel, increase the efficiency of fire emergency response units conducting rescue operations, as well as optimize space planning and structural solutions to ensure a high level of fire safety inside buildings of preschool and general education organizations.

Goals and objectives. The purpose of the article is to validate the updated requirements for designing fire protection systems for buildings of preschool and general education organizations in compliance with the Federal Law of the Russian Federation dated July 22, 2008 № 123-FZ «Technical regulations governing fire safety requirements» (hereinafter – «№Law 123-FZ»).

Methods. An analytical method is used to formulate and substantiate the requirements for designing fire protection systems for educational establishments within the framework of the integrated application of Law 123-FZ and with regard for current trends in architecture and structural design of similar buildings, as well as fire risk calculations.

Results. The results of the work are contributed to the amended sets of effective fire safety rules, such as SP 1.13130.2020 «Fire protection systems. Evacuation routes and exits», SP 2.13130.2020 «Fire protection systems. The fire resistance of protected facilities», SP 4.13130.2013 «Fire protection systems. Restricting fire spread throughout protected facilities. Requirements for space planning and structural solutions» (Amendment 1), etc., as well as SP 251.1325800.2016 «Buildings of general education organizations. Design rules» (Amendment 3).

Conclusion. The research findings were employed to substantiate the current requirements for designing fire protection systems for educational establishments to improve the safety of children in the process of evacuation and rescue, if these buildings have premises featuring various classes of functional fire hazard, fire resistance limits and fire hazard classes of building structures, building materials and engineering installations.

Introduction. Nuclear graphite poses a threat due to the formation of the graphite dust – air mixture (GDAM) during the dismantling of decommissioned nuclear reactors. However, there is no clear answer to the question on the GDAM explosibility. A review of international studies suggests that GDAM is either inexplosive or its explosibility is weak (Phylaktou H.N. et al., 2015). In this paper, the authors advance arguments for the explosion safety of GDAM.

Selected research result. The authors considered a well-known result of a study on the combustion of GDAM with an average particle size of 5 μm, the concentration of about 450 g/m³ in a 1.138 m³ chamber, and an ignitionsource made by Fr. Sobbe GmbH («Sobbe 10 kJ»). The maximum overpressure ΔP_max was 0.47 bar in the chamber, and it fitted the case of an explosive air suspension, according to EN 14034-3 (1 bar = 100 kPa).

Interpretation of the research result. Pressure oscillograms were compared for the following two cases: the case of the maximum manifestation of the GDAM explosion hazard (ΔP_max = 0.47 bar; dP/dt|_max = 3.8 bar/s) and the case of combustion of an ignition source in the absence of air suspension (ΔP_max = 0.027 bar; dP/dt|_max = 2.7 bar/s). The comparison shows that the first 20 ms of a pressure change inside the chamber is mainly due to the combustion of the ignition source: the characteristic values ΔP = 0.03 bar and (dP/dt) ≈ 3.8 bar/s are close to the «Sobbe 10kJ» combustion index in the absence of GDAM. A further increase in ΔP is accompanied by the constant or sharply decreasing value of (dP/dt), which means a monotonous decrease in the flame velocity and proves the incombustibility of GDAM.

Conclusions. Due to the smallness of ΔP_max, GDAM can be considered nonexplosive under normal atmospheric conditions. Dependency diagrams, relating the pressure of combustion products and its growth to time offer important information about the combustion of the air suspension in explosion chambers under the condition of a low dust explosion hazard.

Introduction. Textile materials and products (upholstered furniture, curtains, bedding, decorative items, etc.) are among the most flammable materials in residential and public buildings. They largely affect the fire propagation speed and formation of dangerous fire factors in combustion. Therefore, the issues of improving the requirements governing their fire-safe use are particularly relevant.

Aims and purposes. Presently, the fire safety of furniture products is regulated by the Technical Regulations of the Customs Union 025/2012 «On safety of furniture products» in Russia. However, differences in testing procedures and evaluation criteria, demonstrated by the applicable standards, do not always allow objectively assessing the flammability of upholstered furniture products and predicting their behaviour in case of fire. There is also no method for assessing the flammability of mattresses, and the currently used testing method, set by GOST R 53294–2009 (p. 5) cannot ensure a correct assessment and, hence, it results are distorted. The purpose of this work is to conduct an analytical study on foreign regulatory frameworks for the fire-safe use of upholstered furniture elements in public and residential buildings, to make an experimental assessment of the flammability parameters of materials and upholstered furniture, as well as develop proposals for improving the methodological approach to the fire hazard assessment and the use of mattresses in public and residential buildings.

Results and discussion. The analytical studies have proven that fairly developed regulatory and methodological frameworks are in effect abroad. They ensure the fire-safe use of items of upholstered furniture on the premises of residential and public buildings and structures. Comparative experimental studies were conducted to assess the flammability of various composite combinations of mattresses and upholstered elements of furniture using GOST R 53294–2009 methods (p. 4 and 5), which identified large discrepancies between the test results due to the difference in the conditions of the thermal exposure in the course of testing.

Conclusions. It is necessary to develop and introduce a standard method of testing the flammability of mattresses into the domestic regulatory practice. It is advisable to set the requirements limiting the use of flammable elements of upholstered furniture in places of the mass presence of people to reduce fire propagation in case of ignition and formation of dangerous factors.

Introduction. The authors emphasize the importance of pre-explosive concentration sensors, that ensure the required fire safety (FS) at fire/explosion hazardous facilities of oil refineries. The authors substantiate the importance of maintenance procedures for first-level alarming devices that are part of automated process control systems (APCS) installed around outdoor facilities of refineries.

Theoretical fundamentals. The authors argue that two counter-running subprocesses (destructive and creative (restorative)), that ensure fire safety, can describe a decrease in the efficiency of APCS subsystems in the FS monitoring, as well as their restoration at refinery facilities. The proper maintenance of gas detectors is presented as a discrete creative subprocess. The authors demonstrate a relation between the spatial location of sensors of stationary gas analyzers and the computability of their number, depending on the outdoor facility perimeter.

Research results. To mathematically describe the maintenance procedure applied to stationary gas analyzers, the authors assess the dependence between the number of remote detectors, the perimeter of the rectangular outdoor unit, around which they are installed at a refinery, and the prescribed distance between the sensors.

Conclusion. This assessment conveys the features of installation of gas detectors of any type depending on their classification based on physical methods of analysis. A conclusion is drawn that the perimeter data can help to calculate the number of rows for the installation of devices, the length of each row, the prescribed number of gas detectors in each row.

Introduction. The article offers an analytical review of domestic and foreign publications on the fire safety of hydrogen refueling stations and garages for hydrogen-powered vehicles.

General characteristics of the fire hazard of infrastructure facilities for hydrogen-powered vehicles. The authors offer the general characteristic of a specific fire hazard from facilities using compressed and liquid hydrogen.

Hydrogen refueling stations. Refueling stations using compressed and liquid hydrogen were considered in the article. It was found that compressors are the most hazardous items installed at refueling stations; therefore, the value of potential risks, arising in the area of a refueling station, exceeds 10–4 year–1. Experiments, simulating accidents at hydrogen refueling stations, are described. According to the authors, the minimal distance between the compressor and facilities located outside the station area should exceed 50 m.

Garages for hydrogen-powered vehicles. Features of the fire safety of garages for hydrogen-powered vehicles were analyzed. The authors have found that the overpressure inside a small garage (an individual garage) can reach 55 kPa in case of a jet flame caused by the release of hydrogen through the safety valves of fuel tanks. The overpressure of a hydrogen jet can reach 10 kPa in case of the unignited release of hydrogen. High pressure values that accompany the jet formation are triggered by the high normal burning velocity of hydrogen that boosts the velocity of heat release in the flame front, exceeding the same value for flares of hydrocarbon gases. Therefore, requirements, applicable to storage premises designated for vehicles powered by hydrocarbon fuel, may be erroneously extended to garages for hydrogen-powered vehicles (pursuant to NFPA 2).

Conclusions. The results of this analysis can be contributed to regulatory documents to be developed in the area of fire safety of infrastructure facilities for hydrogen-powered vehicles.

Introduction. The purpose of this work is to obtain experimental data on the numerical dependence between the strength characteristics of the most widely used grades of rolled structural metal products (including those featuring high heat resistance) and a critical increase in temperature.

Materials and methods. As the subject of research we used specimens of rolled metal of the following strength classes: С255 (steel St3sp), С345 (steel 09G2S), С390 (steel 14G2), and rolled metal that had high heat resistance properties S355P (steel 06MBF). Small cylindrical specimens of type B, with M10 thread on heads and the working diameter of 4 mm were used to conduct the static tension and compression tests of mechanical properties. The procedure encompassed the heating of the specimens to the pre-set testing temperature at the rate of not more than 10 °C/min, their 15-minute exposure, and testing for static uniaxial tension/compression.

Results and discussion. The results of the experimental research on mechanical properties of different widely used grades of rolled structural steel, including heat resistant rolled metal, subjected to the fire impact, are presented in the article. The data are presented in the form of diagrams used to make a quantitative assessment of the effect of elevated temperature on the strength properties of rolled structural metal under the impact of fire. This information can be contributed to the design and operation of structural metal constructions to develop analytical methods of identifying the fire-resistance limits of constructions made of structural metal.

Conclusion. The new data on the fire resistance of metal products allow for a more reasonable building design, higher safety and resistance of buildings and structures to the effect of fire. A wider area of application of the whole range of rolled products featuring higher heat resistance will reduce metal consumption and construction costs, boost competitiveness and attractiveness of steel structures and their application in the construction of buildings and structures of various purposes.

Introduction. An important factor of the proper operation of the whole fuel and energy sector is the fire safety of its process facilities, designated for the transportation and distribution of electricity (power stations, transformer units), oil products and combustible gas (compressors and main pumps). These items of equipment are self-contained low-maintenance facilities located in remote areas.

Scope of problems. The fire safety of self-contained low-maintenance fuel and energy facilities, including power stations, compressors and main pumps, entails the involvement of the field forces that cannot ensure reliable and effective fire protection at all times, given the economic inexpediency of their establishment at these facilities or their remoteness from the facilities. The authors propose using automatic fire safety systems composed of robotized fire extinguishing units and water film heat shields that may operate in the stand-alone mode.

Research results. The authors have proven the ability of water film heat shields and stationary robotized fire extinguishing systems to ensure the fire safety of self-contained low-maintenance fuel and energy facilities. The proposed items of equipment should operate in the autonomous control mode that ensures timely and sufficiently effective fire protection by reducing the thermal impact of outdoor fires without the involvement of quick response teams.

Conclusions. Given the need to ensure fire safety, the use of self-contained and low-maintenance fuel and energy facilities equipped with automatic fire extinguishing units that have robotized water monitors and water film heat shields is an effective alternative to quick response teams.