The placement of fire detectors in conditions of a protected facility significantly affects the efficiency of the detection of fire factors by fire detectors. Problems of the placement of point-type smoke, heat, and gas fire detectors in premises with engineering structures in the ceiling area located at a certain distance from the ceiling have been considered. The combustion source generates a convection column that carries fire factors (heat, smoke, and gaseous combustion products), usually with an opening angle of about 15°. Having reached the ceiling, the airflow generated by the convection column starts spreading horizontally in all directions. The horizontal component of the rate of propagation of fire factors depends on the intensity of a combustion source and the distance from the fire source axis. The process of the spread of fire factors in the ceiling area changes in case of beams, ventilation ducts, and other engineering and technological structures located on the ceiling that protrude from a partition and prevent the spread of fire factors. It is common that a gap remains between the partition and the upper part of engineering structures, i.e., the engineering structure is not installed directly to the ceiling but at some distance from it. In this case, the main parameters affecting the distribution of fire factors are the height of the gap, the width of the engineering structure, and the horizontal air mass velocity generated by the airflow from the fire source and depending on the intensity of the combustion source. In case of a slowly developing smoldering characterized by the low velocity of airflows, fire factors may not bypass the gap between the engineering structure and the partition, whereas in the case of intensive combustion accompanied by active movement of air masses, the heat, smoke, and gaseous combustion products will pass the gap freely. The experiments have used five types of point-type smoke fire detectors. The following test fire sources have been used as a combustion load: TF-2A (pyrolysis smoldering of wood) and TF-5 (combustion of a flammable liquid with smoke emission). The test fire source TF-2A generates a lower air mass velocity when compared with the TF-5 source. A 500 mm wide box simulator has been used as an engineering structure. The first test has been conducted without the box in the ceiling area. Then, the box simulator has been alternatively installed in the ceiling area, creating a gap between the partition and the upper plane of the box of 50, 100, and 200 mm. The test fire source has been placed from one side of the box simulator’s projection to the floor, whereas fire detectors have been installed in the ceiling on the other side of the box simulator. During the tests, the activation time of fire detectors has been controlled. The test results confirm the theoretical conclusions.

The study proposes a methodology for the experimental determination of the specific crushing energy of a hard coal sample. An experiment to study the process of the destruction of coal samples selected from a coal seam prone to coal and gas outbursts has been conducted. For these purposes, a device has been designed for mechanical impact on the coal sample with a load of known mass dropped from a certain height. Data on particle distribution by average diameters during the coal sample destruction have been obtained, as well as the dependence of specific crushing energy on the average-weighted radius of coal particles. Potential values of the specific energy of coal elastic compression have been calculated based on the values of measured stresses in the coal mass. The range of measured maximum stresses was 20–50 MPa. The stress-concentration factor during secondary subsidence can reach 8–9, which complies with the increase of stresses of the same depth up to 80–90 MPa that leads to the coal destruction to small-size particles: 1–60 µm or smaller. Comparing the experimental and calculated values of the specific energy of coal elastic compression has shown that these values comply with the particle size of 1–50 µm. The dependence of the generation of particles of different sizes on the type of deformation impact on a coal seam has been considered (compression across seams, compression along seams, and shear along seams). It has been established that the smallest particles are generated under shear deformations. A methodology for predicting gas emission from coal when destructed to specific size particles, developed by the authors, has been proposed. Knowing the dispersed composition of a section of coal seam, considering natural gas content and size pore distribution, the maximum volume of gas emission from a given section can be estimated, which will help develop preventive measures and thus increase the safety during the underground development of hard coal deposits.

Today, the issue of the impact of hazardous production factors remains one of the most relevant at the global level, as their consequences may cause illnesses, injuries, and a negative impact on the environment. The construction worker protection measures developed earlier basically related to the impacts of electromagnetic fields indoors, whereas these were considered less harmful at outdoor construction sites (0,2µT). The nature of occurrence, the negative impact, the risk analysis, and the measures to reduce the impact of low-frequency electromagnetic fields on construction workers have been considered. The impact of a low-frequency electromagnetic field on a welder’s workplace in real conditions has been conducted with the VЕ-metr device. The electromagnetic field strength has been measured in each working area at a height of 1.5 m from the equipment maintenance area surface and at a distance of 0,5 m from the equipment. The measurements have been conducted at the highest operating voltage and the maximum operating current of the electric equipment. A dependence of various systems of the human body on the frequency and intensity of external electromagnetic radiation has been identified. The impact of a low-frequency electromagnetic field at 1 kV/m has negatively affected the workers’ health status. Comprehensive measures to prevent occupational illnesses of enterprise workers have been recommended.

Every year, the number of fires caused by cables and wires is growing. Burning of cables is accompanied by active emission of heat and toxic products. The analysis of scientific papers and tests has shown that the conductor's shape, the number of cable cores, the insulation material, the number of conductors, and their packing density affect this process. The study considers the impact of burning cable lines in cable ducts on the temperature of enclosing structures of a building in a standard temperature mode. For these purposes, fire tests and modeling have been conducted in the ANSYS software package. Experimental units involved in tests have different structures, which helped estimate the heating of adjacent building structures in various conditions of the tests. The goal of the calculation has been to model the thermal impact on enclosing structures when a heat source is located immediately inside the duct. The results of modeling have shown a significant thermal impact on enclosing structures where the temperature of the partition surface exceeded 600 °С. The obtained results can be used, inter alia, for studies aimed at the assessment of the efficiency of fire-protective coatings of various mechanisms of action.

The dust content in the working area during the production of crushed stone remains a key problem for the prevention of occupational illnesses to which 2 % to 12 % of employees are exposed, even when a plant is equipped with modern dust suppression units. The issue of increasing the efficiency of dust suppression with wetting agents has not been addressed yet and requires a comprehensive study of properties and the search for additional factors determining their efficiency. The study aims to select efficient surfactants as wetting agents to suppress dust at a crusher plant. To determine the key factor characterizing the efficiency of dust suppression with wetting agents, comprehensive studies of properties of efficient surfactants have been conducted, including measuring the surface tension at the «solution–air» boundary, the wetting ability, the time of wetting, dust dispersibility, and sprayed solutions. As studies have shown, the surface tension of water solutions plays the key role in the determination of wetting ability, increasing from 70 % to 95 % when the surface tension is reduced from 72.86 mN/m to 26.07 mN/m. Measuring the time of submersion of dust particles into a water solution has detected an exponential dependence on the surface tension; however, the wetting time is reduced by 167–720 times when the surface tension is reduced. The surface tension impacts the interaction between dust particles and the solution of surfactants and the formation of drops during the dispersion, whose dispersibility increases by more than twice. Based on the comprehensive analysis at the crusher plant, wetting agents based on sodium sulfate (C8–C10) or zinc cocosulfate have been recommended for use. The approximation of the obtained data helps to forecast the basic characteristics of wetting agents outlining the efficiency of dust suppression of silica dust. The study results can be used when selecting an efficient wetting agent for dust suppression during production, as well as for manufacturers involved in the development of wetting agent compositions.

It is required to establish the advisability of determining real coal density using empirical dependences obtained based on statistical processing of technical analysis indices and their compliance with results obtained by the standard method. The methodology is based on the comparative analysis of design values’ compliance with real coal density for each mine seam, in accordance with empirical equations, with their values obtained by the standard method. The reliable determination of actual coal density values is required to identify mine seam tendency to spontaneous coal and gas outbursts during mining operations and to forecast and control gas emissions during coal production at coal mines. A significant mean square deviation from average curve, exceeding up to ten times the accuracy of the determination of actual coal density by the standard method has been established, which excludes a practical possibility of using design values by empirical equations to forecast mine seam tendency to spontaneous coal and gas outbursts and to control gas emissions during mining operations. Real coal density is a strictly individual property of a specific mine seam. It can be reliably determined only by the standard method. Average empirical dependences provide only a tendency of change of real coal density under metamorphic transformations of mine seams. For the first time, based on statistical processing of coal density experimental data and indices of technical analysis for 590 mine seams of the Donbass and Lviv-Volyn basins, the unacceptability of the use of design values in accordance with empirical equations to forecast mine seam tendency to spontaneous coal and gas outbursts has been proved. The results of the studies help develop proposals for the improvement of the regulatory framework for the forecast of coal seam outburst hazard.

Due to its unique properties, gold has always played a significant role in the global economy as a valuable financial asset and is still considered a highly demanded metal in the contemporary industry. Specialized affinity companies are involved in the production of pure high-grade gold (999.9). Gold production is a complex process with its specific features, among them expensive chemicals and equipment, harmful microclimate in premises, labor-intensive workflows, loss of precious metals with waste, and the use of toxic substances. Despite the numerous accident risk assessment methods applied, a method that could consider all features of gold production is required. Therefore, today, the development of the accident assessment method considering the aspects of gold production is a relevant scientific problem. The main stages of the production process have been considered as follows: smelt intake, Miller process, electrolysis in «aqua regia», smelting of finished products, and pouring of measured ingots. For each stage of the gold production process chain, specific hazards and accidents (incidents) that might be caused by them have been detected. Some hazards, such as complete or partial blackout, the use of lift-loading facilities and technical devices, load falls, destruction of the lining of the induction furnace, and discharge of melt, are the most common and specific to several production areas. Handling hydrochloric and sulphuric acids and gaseous chlorine requires specific storage and use conditions in order to avoid emergencies. Groups of criteria that consider the specifics of gold production, i.e., natural, technological, structural, unintentional human factor, intentional human factor, and others, have been developed. Among the most distinguishable features of gold production facilities are the limited access to facilities, a high level of secrecy, and increased safety measures, which may hamper personnel’s evacuation in case of an accident. This must be considered when assessing accident risk. The criteria provided in the study help to detect hazards for each stage of the gold production process, thus helping to predict emergencies and develop necessary protective measures for both a specific workflow and the production as a whole.

The information on legislative documents of the Russian Federation regulating companies’ activities in the sphere of industrial safety has been provided. The relevance and advisability of using a systemic-structured process approach at the stage of the development and implementation of the industrial safety management system, considering the provisions of GOST R ISO 45001—2020 (safety and occupational protection management), have been substantiated. A methodological substantiation of the use of the process approach to the development of an industrial safety management system based on the systemic approach using the well-known cycle of Deming (Plan, Do, Check, and Act) has been provided; basic problems of its applicability have been considered. A matrix of processes and subprocesses in accordance with the sections of the Order of Rostechnadzor № 103 considering GOST R ISO 45001—2020 and process typology according to ISO/TC 176/SC 2/N 544R3 has been elaborated; processes of company management, measurement, analysis and improvement, key processes, and resource management processes have been considered; process ranking by level has been completed. A model of industrial safety management system has been developed based on the process approach, structural analysis technology, and Structured Analysis and Design Technique (SADT), as well as the functional modeling methodology IDEF0 (Integration Definition for Function Modeling). The main context diagram of the industrial safety management system in the IDEF0 notation has been developed. The decomposition of processes and subprocesses of the second and third levels is presented, and all their functional connections are described. The provided methodology of process modeling enables a positive effect in the minimization of expenses and the development period of a systemic model of the industrial safety management system. It has been demonstrated that the process approach used for the design of a systemic model of the industrial safety management system considering the provisions of GOST R ISO 45001—2020 helps structure the process composition, precisely determine input and output process parameters, process participants, resources, ensure control and adjustment of processes, increase the safety level, improve working conditions, and ensure compliance with legislative requirements.

Processing titanium alloys such as VT23 in the superplasticity forming mode is a key technology in the aerospace industry. At the same time, it is associated with high risks for personnel. The processing temperature reaches 900 °C, which requires using heat-resistant equipment, powerful ventilation systems, and protection against toxic emissions. These factors hamper experiments, especially in conditions of educational labs with limited resources. The solution for the problem is the use of low-temperature model alloys such as POS61 (tin-lead alloy) and Wood’s alloy that imitate the titanium behavior during the superplastic formation, but in safe conditions. The goal of the research has been to evaluate the efficiency of these materials in order to reduce occupational risks and streamline modeling processes. POS61 alloy that demonstrate superplasticity at 100–150 °C, and Wood’s alloy with excessive plasticity, have been used as modeling materials. For the comparison, VT23 titanium alloy processed at 700–900 °C has been used. Research methods have included mathematical modeling of formation processes of a box body via the finite element method and stretch tests at deformation rates of 0.001–0.004 s–¹. The modeling results have shown that forming a 1 mm thick part of POS61 and a 2 mm thick part of titanium ВТ23 causes a similar distribution of deformations. The smallest thickness upon processing has been 0.38 mm for POS61 and 0.34 mm for VT23, which confirms the adequacy of the modeling material. Stretch tests have detected that under temperatures within 100–150 °C, POS61 obtains strength properties similar to titanium, whereas Wood’s alloy, despite its high plasticity, proved to be inapplicable for precise modeling due to its low strength. Using POS61 opens up new opportunities to optimize technologies in aerospace mechanical engineering, reducing the dependence on expensive equipment and increasing occupational safety. Implementing these solutions not only facilitates the protection of employees’ health but also accelerates the implementation of innovative methods of material processing.

To ensure the safety of employees, protective helmets that have been proven as reliable personal head protective equipment against mechanical impacts are widely used. However, these have one significant flaw, which is a low electric conductivity of the material they are made from, which conditions a potential generation and accumulation of electric charges on their surface during a contact electrification «protective helmet – scalp hair». Electric charges accumulated on the surface of a protective helmet can cause, as a result of electrostatic discharge, the ignition of many combustible substances and volatile liquids considered explosive and fire-hazardous that are used in production premises. The study addresses the problem of selecting a method to prevent electric charge accumulation resulting from contact of scalp hair with elements of protective helmets. A calculation method determines a minimum metallized (grounded) area of internal surface of a protective helmet that, in case of grounding, will ensure the flow of charges to the grounded poles. The first condition under which no electric charge generated due to the electrification of the employee's scalp hair when contacting the integral harness of the helmet can become an inflammation source, has been obtained for a specific combustible substance with minimum ignition energy and a specific ungrounded surface of a protective helmet. The dynamics of electrostatic potential of preliminarily charged elements of the internal harness of a protective helmet in relation to the ground from the moments of their connection to a grounding device, with registration of the time of charge flow to the one-tenth of initial values, has been studied by a non-contact method, and its results have been provided. As a result, the dependence of the rate of charge flow on the area of grounded conducting coating on the internal surface of a protective helmet has been determined. The results of the study refer to the necessity to develop a methodology for protective helmet tests during their production and to introduce amendments into their test programs.