Introduction. The results of a standard study on the explosion hazard of polyethylene air suspensions (PES) can contribute to the theory of turbulent combustion. For example, analysis of polydispersity data and values of the PES lean combustion limit in a 1 m³ chamber helped to identify the maximum size of explosive particles d^*_m,t ≈ 100 µm (Poletaev, 2014). In this work, a relationship was obtained between the dynamics of PES combustion in a 1 m³ chamber and the average particle size of the suspension, which is understood as the average particle size of its explosive fraction d^*₅₀.

Initial data. Well-known findings of a study on the explosion of 28 polyethylene specimens in a 1 m³ chamber were used. Continuous functions of specimen particles distribution by size, necessary for calculating d^*₅₀, were represented using the Rosin-Rammler distribution.

Combustion dynamics. The dynamics of PES turbulent combustion in a 1 m³ chamber is described by the maximum rate of air suspension burnout U_b. U_b was calculated according to the formula (Kumar, 1992) intended for gas-air mixtures by substituting PES explosion parameters into this formula.

Results and its discussion. The graph, describing the dependence of the complex d^*₅₀U_b on d^*₅₀, is provided. The averaged value of the complex (≈ 45 µm · (m/s)) is constant in the range 40 µm < d^*₅₀ < 90 µm. The latter is typical for the product of the particle size and the normal velocity of laminar flame in liquid aerosols (Myers, 1986), which indicates similarity between the effect of particle dispersion and dynamics of turbulent and laminar combustion of the aforementioned heterogeneous mixtures.

Conclusions. The dispersive capacity of an explosive polydisperse polyethylene specimen is determined by the average particle size of the explosive fraction of the specimen d^*₅₀. The similarity of combustion patterns indicates the proximity of propagation mechanisms typical for turbulent flame, typical for PES, and laminar flame, typical for liquid aerosols.

Introduction. The application of PROZASK fire-retardant panels demonstrates an option for and the expediency of a comprehensive study of fire proofing characteristics.

Goals and objectives. The mission of this research project is to (1) obtain the results of experimental studies of fireproofing panels, containing the cement binder, (2) determine their fire proofing efficiency, using the radiant heating test bench that reproduces pre-set modes of high-temperature exposure, and (2) analyze the testing results using the method of mathematical modelling of temperature fields inside fireproof structures.

Methods. Standardized laboratory techniques were used to clarify the thermal-physical characteristics of boards at relatively low temperatures. Their fire proofing efficiency was evaluated in the course of additional testing of specimens using the radiant heating test bench. A reliable and relatively uncomplicated method and programme for calculating unsteady temperature fields in fireproof structures were used to conduct the thermal analysis and generalization of experimental results. The authors summarized the results of standardized tests, conducted in a fire furnace, to determine the flame-retardant efficiency of PROZASK Firepanel boards and the fire-resistance of the full-size structures they protect.

Results. Values of specific heat capacity and the thermal conductivity coefficient of boards, tested using  laboratory benches at relatively low temperatures, were verified. The results of thermocouple measurements, taken during the testing of specimens with the help of the radiant heating bench in standard and hydrocarbon temperature modes, were obtained. The processing of these results, using thermal engineering analysis, allowed determining the values of the thermal conductivity coefficient in the range of operating temperatures. The influence of moisture, contained in the boards, on their fire protection efficiency was evaluated. Comparison between the results of calculations and tests, conducted in the fire furnaces, showed the practical usability of the obtained characteristics of boards and the thermo-engineering analysis used to (1) clarify the fire-proofing efficiency and the design developed using PROZASK Firepanels and (2) evaluate the fire-resistance of the constructions they protect.

Conclusions. The presented integrated studies generated a considerable amount of important information, required to prognosticate the fire proofing properties and the fire-resistance of constructions that contain PROZASK Firepanels. The role of additional testing of specimens using a radiant heating test bench and the effectiveness of thermal-engineering calculations as a tool for assessing the parameters of fire proofing  and the fire resistance of structures are demonstrated.

Introduction. High temperatures cause deformation of steel structures which also lose stability and the bearing capacity, resulting in the collapse of structures with the subsequent collapse of the building. It is understood that intumescent paints are often used to increase the fire-resistance limits of steel structures up to R 90 and R 120. However the fire protection effectiveness of intumescent paints has not been sufficiently studied for the case of the long-term operation, and the application of this type of fire protection treatment of bearing steel structures requires justification. To ensure the building stability, coupled with the required fire resistance limit of structures, one should study the engineering factors affecting the fire resistance of steel structures that have intumescent paint coatings.

Purpose of the research work. Development of approaches to simulation of nomograms demonstrating the heating of steel structures with flame retardant coatings of different thicknesses. The research work solved the following tasks:

• block diagrams of the research undertaking were developed to find the fundamental relationships between the dynamics of change in the structure of fire protection materials under thermal effects and the fire resistance limit of a building structure based on the choice of the functional criterion;
• mathematical models demonstrating dependence between the thickness of the dry layer of fire-retardant material were developed; the required fire resistance limit and thermo-physical characteristics of fire-resistant materials based on the experimental studies of the properties and effectiveness of fire-resistant materials were identified;
• nomograms showing dependences between the thickness of the dry layer of flame retardant materials and the flame retardant efficiency of flame retardants were made.

Research methods. Hot Disk TPS 1500 thermal constant analyzer was used to analyze the thermo-physical characteristics of flame retardant materials. Thermal analysis was used to study the properties of flame retardants, as well as physical and chemical transformations occurring inside them under the programmed exposure to temperature effects and with the use of specialized thermal analysis equipment. The study of the fire protection efficiency for steel structures was conducted in accordance with GOST R (Russian State Standard) 53295–2009 “Fire protection means for steel structures. General requirements. The method of fire protection efficiency determination”.

Results and their discussion. As a result of the research, an approach to prediction of the fire resistance of building structures was developed in the form of a research flowchart, used to choose the functional criteria. Experimental studies were conducted to identify mathematical dependences between the fire resistance and the indicators, which serve as functional criteria. In particular, when assessing the fire resistance of steel structures, a prediction is made on the basis of thermos-physical indicators. The authors were first to propose the introduction of the function of fire protection materials into the standard pattern of fire resistance analysis in the course of solving static and thermo-physical problems. The obtained data were used to make equations of dependence between the thickness of a dry layer of a fire-retardant material, the required fire-resistance limit of a structure, and the nomogram showing the heating of protected steel structures with fire-retardant coatings of various thicknesses.

Conclusions. The results of the studies allowed identifying fundamental relationships between the dynamics of change in the structure of fire-retardant materials under the thermal effect and the fire resistance limit of a building structure on the basis of the choice of a functional criterion. Experimental studies of the properties and effectiveness of fire-resistant materials were conducted to develop a mathematical model showing dependence between the thickness of the dry layer of fire-resistant materials, the required fire-resistance limit and thermal-physical characteristics of fire-resistant materials.

Introduction. The article presents a comprehensive security system created at the enterprises of the oil and gas complex of Russia, which requires constant improvement and development. The transition of the system under consideration to a new qualitative level is possible with the development of an integrated intersectoral approach based not only on the use of scientific and technical achievements in the field of reliability of the functioning of physical objects, but also in the development of new scientific results for the implementation of organizational and technical measures in the complex security of enterprises.

Goals and objectives. The main purpose of the presented article is to improve the state of the integrated safety system at the enterprises of the oil and gas complex of Russia, by solving the tasks of rational and targeted development of subsystems (industrial and fire safety, labor protection), their transition to a new qualitative level of development.

To achieve the goal, 4 tasks requiring solutions are formulated.

Results of solving problems.

When solving problem No. 1, conclusions are drawn:

• the average proportion of all joint events summing up by years causing damage (accidents and fires) is about 20 % per year;
• the average economic damage from joint hazards (accidents and fires) is about 40 % of the total damage per year, i.e. about 1.5 billion rubles;
• the average level of sanitary and irretrievable losses of personnel at the enterprises of the NGK of Russia is about 38 %, about 300 people per year.

In solving problem No. 2, the formulated concepts for integrated security, integrated security systems, rational and targeted development of the integrated security system at the enterprises of the oil and gas complex of Russia are presented.

When solving problem No. 3, a model is presented that allows comparing the qualitative indicators of the functioning of existing and developing integrated security systems at the enterprises of the oil and gas complex of Russia.

When solving problem No. 4, the use of a new rational-target model of the development of the CB system at the enterprises of the NGK of Russia is justified and demonstrated, and an example is presented that proves the adequacy of its use.

Conclusions. The application of the developed rational-target model for the development of the CB system at the enterprises of the NGK of Russia, allows in practice to solve the problem of reducing damage from accidents and fires in the system under consideration, i.e. to solve a problem of important socio-economic importance for Russia.

Introduction. Intumescent coatings are used as a means of protection from heat flows, and their mission is to preserve the operability of wires and cables under fire conditions coupled with simultaneous current loading. However, the effect of insulation destruction on the operability of cables has not been studied for the case of a real fire regime.

Goals and objectives. The purpose of the article is to evaluate the experimental operability of electrical wires and cables subjected to simultaneous effects of fire and current loadings.

To achieve this purpose, an experimental testing unit was applied to conduct the experimental testing of wires and cables manufactured by various producers. At the same time, the temperature effect of the heated environment on electrical parameters of wires and cables, such as resistivity, inductance and capacitance, was evaluated.

Theoretical background. In real fire conditions, dependence of indoor temperature, affecting the heating of cable insulation, differs essentially from the same dependencies in cases of various standard fire conditions. Therefore, the insulation destruction process may occur before the coating intumescence starts.

Results and discussion. An experimental testing unit has been developed. This unit allows for the gradual cable heating with a pre-set temperature measurement interval and cable electrical characteristics. Dependencies of resistivity, inductance and capacitance of standard electrical cables on the temperature of the air surrounding the cable are obtained. It’s been discovered that the gradual heating of an electrical conductor or cable eventually leads to a short circuit between its conductive cores and further electric current transmission in electrical wires and cables. It is shown that phases and amplitudes of an input electrical signal can drastically change before the short circuit.

Сonclusions. The simultaneous effect of fire and current loadings on standard electrical wires and cables causes a short circuit in the temperature range, in which no intumescence of flame retardant coatings is initiated on the insulation surface. Therefore, these coatings can ineffectively maintain the operability of electrical wires and cables.

Introduction. The article contains a theoretical study on the influence of climatic conditions in various regions of the Russian Federation on the heating of a side wall of a liquified hydrocarbon gas (LHG) tank if the firе runs through the whole vehicle, located at a gas station. Objectives of the study:

• analysis of the fire safety legislative framework applicable to gas station design;
• analysis of sources of domestic and foreign experimental studies on the fire impact of flames on an LHG tank;
• numerical simulation of the vehicle combustion in cold and warm seasons, taking into account the highest wind velocity in the Russian Federation;
• numerical simulations, conducted for a warm season to identify the critical surface temperature of a side wall of an LHG tank, and the design wind velocity corresponding to the air temperature in a Russian region.

Materials and methods. The method of mathematical statistics is used to process maximum values of the air temperature and wind velocity for each Russian region and obtain the empirical values of the wind velocity and air temperature in the Russian regions. Calculations were made using the method of mathematical modelling of fire in warm periods to identify the critical surface temperature of a side wall of an LHG tank and the design wind velocity corresponding to the air temperature in the regions of Russia.

Results. A dependence between the wind velocity and the air temperature in the Russian regions, as well as a dependence between the critical surface temperature of a side wall of an LHG tank and climatic conditions of the Russian regions was identified.

Conclusions. The results, obtained by the researches, can be used to design the fire separation distance between the site designated for a fuel tanker truck (the parking lot for a vehicle before its fueling), an LHG tank and a gas station. 

Introduction. The authors present the results of testing single and double glazing, used as explosion relief structures (ERS) to ensure the explosion resistance of buildings and structures in case of indoor explosions caused by accidents. The criterion of comparative effectiveness of ERS is the value of maximum pressure inside the premises caused by an emergency deflagration explosion and the response of an explosion relief structure. The lower the maximum pressure under otherwise equal conditions (the volume of the room, the area of the relief opening, the type of the explosive mixture), the higher the ERS effectiveness.

Goal and objectives. The purpose of this study is to experimentally determine the effectiveness of glazing used as an explosion relief structure in case of emergency deflagration explosions inside buildings. It is necessary to solve the following tasks to attain the pre-set goal:

• experimentally determine the relief pressure of ERS, or single and double glazing during an indoor deflagration explosion;
• determine the maximum pressure inside the explosion chamber using glazing as ERS;
• conduct the comparative (also numerical) analysis of the results of experimental studies to confirm the accuracy of the ERS relief pressure value;
• compare the results of experimental studies with the calculated values of the ERS relief pressure obtained using the methods recommended in the regulatory documents.

Research methods. In the course of ERS testing, an explosion chamber, having the operating volume of 8 m³ and the relief opening area of 1.3 m² was used. Hence, the specific area of the ERS was 0.16 m² per 1 m³, which is 3.2 times higher than that recommended in the regulatory documents. Therefore, any pressure, exceeding the threshold values (5–7 kPa) inside the explosion chamber, unambiguously shows the ERS inefficiency. Results and their discussion. The results of testing the 4 mm single glazing and the area of 1 m² (meeting the requirements of paragraph 6.2.30 of SP (Construction Regulations) 56.13330.2021) show that such glazing is ineffective as the ERS. Excessive relief pressure and maximum pressure in a room with an extra area of the relief opening have high values: P_rel = 11 kPa; P_max = 12 kPa. Such loadings are destructive for industrial buildings and structures.

High values of relief and maximum pressures (14.7 and 17.7 kPa) in a chamber (17.7 and 20.5 kPa) allow drawing a conclusion about the inefficiency of double glazing as ERS.

In the course of testing both single and double glazing, considerable glass fragment dispersion (up to 30 m deep and up to 13 m wide) was observed, which could result in the injury of people near the building during  an accident.

Conclusions. Experiments have shown that the assumed (calculated) glazing deflagration pressures, recommended by a number of regulatory documents and research publications, may differ significantly from the actual values, which may cause building collapses as a result of indoor explosions.

Introduction. The number of accidents at gas stations has increased lately. Gas stations provide maintenance and fueling services. Gas stations are dangerous because they store fire hazardous automobile fuel, as well as equipment under pressure that may contain explosive gases. For safety reasons, it is necessary to analyze the causes of these accidents. The purpose of the work is to conduct a statistical analysis of accidents at gas stations to identify patterns of accidents.

Analysis. The article presents the statistics of accidents at service gas stations in the Russian Federation for 10 years from 2012 to 2021. The data is provided by the National Crisis Management Centre of the Ministry of the Russian Federation for Civil Defense, Emergencies and Elimination of Consequences of Natural Disasters (Emercom of Russia). The analysis of accidents at gas stations is broken down by the constituent entities of the Russian Federation. Causes of fires are indicated; ignition sources are considered, locations of fires and facilities are listed. Fires at gas stations were considered taking into account the categorization of objects in accordance with government decree “On Application of a Risk-Oriented Approach to Organization of Certain Types of State Control (Supervision)”.

Conclusion. The statistics, provided and analyzed in the article, can serve as the basis for a scientific research project on the fire safety of gas stations.