Fire Safety

FACTORS INFLUENCING THE BURNING RATE OF COMPOUNDS FROM WHICH FIRE EXTINGUISHING AEROSOLS ARE FORMED

V. M. Balanyuk — 2024-12-30

The article deals with the topical issue of the influence of various factors on the combustion rate of fire extinguishing aerosol compounds (AFC). Aerosol fire extinguishing agents are becoming increasingly popular due to their efficiency, low fire extinguishing concentrations and environmental safety. However, for their effective use, it is necessary to understand and control the factors that affect the burning rate of AFC and the formation of fire extinguishing aerosol. To identify and analyse the factors affecting the burning rate of AUS in order to optimise their composition and increase the efficiency of fire extinguishing. The method of scientific analysis and synthesis, as well as the experimental method of research were used in the work. The main factors influencing the burning rate of AFC were determined. The chemical composition and ratio of the components of the AFC (fuel, oxidant, catalysts, additives). Geometric parameters of the AFC charge (presence of channels, holes). Physical properties of the components (melting point, molecular weight). The presence of internally bound oxygen in the molecular structure of the fuel. It has been established that to increase the combustion rate of AFC, it is necessary to use thermally unstable combustibles (rubbers, iditol, sucrose, epoxy resin), the optimal ratio of oxidants (potassium nitrate, potassium chlorate, potassium perchlorate) and catalytic additives. It is shown that ensuring the maximum combustion area of the AFC and the use of a complex geometric charge design contribute to an increase in the rate of fire extinguishing aerosol formation. The combustion rate of AFC is a key factor determining the effectiveness of fire extinguishing. To achieve a high combustion rate, it is necessary to optimise the composition of the AFC, taking into account the chemical and physical properties of the components, as well as the geometric parameters of the charge. Further research should be aimed at a detailed study of the influence of each of the factors on the burning rate of the AFC and the development of new effective compositions of aerosol-forming compounds.

RESEARCH OF THE INTENSITY AND MULTIPLICITY OF COMPRESSION FOAM WHEN SUPPLIED IN A “SUB-LAYER” WAY

V. V. Kovalyshyn — 2024-12-30

Introduction. Improving the efficiency of various firefighting methods is a pressing task for both Ukrainian fire and rescue services and the international community. In their daily operations, fire and rescue units use various types of equipment to extinguish fires, save lives, and mitigate the consequences of emergencies. However, modern challenges require enhancements in firefighting techniques and methods. In particular, the war in Ukraine has significantly altered the approach to firefighting and rescue strategies, emphasizing the need to modernize fire equipment and technology. The improvement of firefighting equipment is especially crucial in the oil industry, which is becoming increasingly vulnerable to emergencies. Special attention should be given to safe firefighting methods, specifically the use of the “subsurface” method with compressed air foam. To properly utilize this method, it is essential to study the properties of compressed air foam and its potential application in “subsurface” firefighting for storage tanks containing petroleum products. The aim of this work is to determine the impact of varying foam delivery intensity and expansion ratio using the “subsurface” method. For theoretical research, the SolidWorks Flow Simulation software was used, and analytical methods were applied to study the use of foam in firefighting. Methods for determining foam quality, expansion ratio, and delivery intensity were also examined. These studies established that delivering compressed air foam with an expansion ratio of 10 (K10) using the “subsurface” method is more advantageous than using foam with an expansion ratio of 5 (K5). Additionally, the required reserve volume of the tank was determined in the case of a 30-minute burn duration before the start of foam delivery. Extinguishing a tank with petroleum products using K5 foam consumed 4019 kg and 4319 kg of foam concentrate at pressures of 3 atm and 4 atm, respectively, which is three times more than when using K10 foam (1377 kg and 1389 kg at the same pressures). The extinguishing time also differed: with K5 foam, the extinguishing time was 598 s and 482 s at pressures of 3 atm and 4 atm, respectively, which is 188 s and 172 s longer than when using K10 foam (410 s and 310 s at the same pressures). Therefore, the use of K5 foam is economically inefficient and takes more time. Using foam with an expansion ratio of 10 for “subsurface” firefighting is significantly more effective than foam with an expansion ratio of 5. The higher the expansion ratio and foam delivery rate, the greater the firefighting efficiency. The required reserve volume of the tank, assuming a 30-minute burn duration before the start of K10 foam delivery and a delivery rate of 56 kg/s, is approximately 13%.

EXPERIMENTAL STUDY OF FIRE PROTECTION EFFICIENCY INDICATORS OF WOODEN BUILDING STRUCTURES WHEN REPLACING FIRE RETARDANT

А. F. Havryliuk — 2024-12-30

Fire protection treatment is one of the effective ways to ensure the proper level of fire safety. The requirements for this process are regulated by the Fire Protection Rules, state standards, regulations and still valid standards of the category. The most common is fire protection treatment of wooden structures, since wood is an affordable, effective and environmentally friendly material, but with high rates of combustibility, flammability, flame spread and smoke generation. Fire protection agents for impregnation are most often used for fire protection of wood. Analysis of the process of checking the effectiveness of fire protection created the prerequisites to state that fire protection agents may not be compatible with each other, which leads to a decrease in fire protection efficiency. Considering the fact described above, taking into account current and newly adopted standards, the study of fire protection efficiency indicators of wooden building structures after repeated fire protection treatment with replacement of the fire protection agent is an urgent task. The purpose of the work is to study the fire protection efficiency indicators of wooden building structures after repeated fire protection treatment with replacement of the fire protection agent. To determine the fire protection efficiency indicators of wooden building structures when replacing a fire retardant, current methods and methods that will come into force from March 2025 were used in parallel. For experimental research, the following methods were used: “Method for determining the fire protection efficiency group of wooden structures”, “Method of controlling by ignition temperature” and “Method of controlling by the sign of spontaneous combustion”. For experimental research, samples were made of pine that were impregnated with fire retardants DSA- 1, Bioflame, Ecosept 450-1, Fire-of separately with each agent and subsequently re-impregnated in various combinations of replacing the fire retardant. Tests to determine the mass loss of wood showed that the mass loss indicators for samples with the replacement of the fire retardant in relation to the mass loss indicators of samples treated with one fire retardant increased in the range from 0.5% to 4.6%, which led to a decrease in the fire retardant efficiency group from I to II and indicates the negative impact of replacing the fire retardant. According to the results of tests according to the “Method of control by the sign of spontaneous combustion”, a number of samples are considered unsuitable for further operation, since the percentage of sections that were tested supported spontaneous flame combustion and (or) smoldering in the range from 20% to 50%. A comparison of the determined ignition temperature indicators with the ignition temperature of pine that was not treated with fire retardants revealed that the ignition temperature increased for all samples. The increase occurred in the range from 5 to 85 °C. Experimental studies of the fire protection efficiency of wooden building structures when replacing the fire retardant have shown that replacing the fire retardant affects the mass loss indicators (increase in loss from 0.5 to 4.6%), signs of spontaneous combustion (maintenance of combustion of more than 20%), and ignition temperature. With the used combinations of fire retardants, a decrease in fire protection efficiency indicators mainly occurred. In some cases, the indicators remained at the same level or improved. The conducted studies give grounds to argue that fire retardants may not be compatible when performing repeated fire retardant treatment, since they lead to a decrease in fire protection efficiency. Further research should be directed to the development of a fire retardant for wood that will be suitable for replacement and will not lead to a decrease in fire protection efficiency indicators.

ASSESSMENT OF THE FIRE RISKS OF ELECTRIC VEHICLES

L. F. Dzyuba — 2024-12-30

Statistics on electric vehicle fires and relevant research in this direction indicate that the frequency of electric vehicle fires worldwide is much lower compared to the statistics of fires in cars running on internal combustion engines. In the USA, 284,130 internal combustion engine fires account for 55 cases of electric vehicle fires. In addition, studies show that the probability of an electric vehicle battery catching fire in a traffic accident is much lower than that of a conventional car catching fire. The purpose of the work is to assess the risk of ignition of the lithium-ion battery of an electric vehicle. To achieve the set goal, the following tasks were carried out: risk factors for the occurrence of fires in the lithiumion battery of an electric car were identified, statistical data and cases of electric cars catching fire due to the failure of the lithium-ion battery were analysed, and a matrix of risks of fires in an electric car was constructed. To achieve the goal of the work, a comparative analysis of statistical indicators was used, followed by analytical processing of the obtained results and their generalization and identification of relevant patterns. According to the carried out assessment of the risk of electric cars catching fire, the following main reasons for electric cars catching fire were determined, namely: human negligence/negligence in production (10%), spontaneous combustion for unknown reasons (22%), malfunction of the battery during charging or after (28%), road accident (30%), drowning (5%), fire action (5%). Taking into account the conducted analysis and existing approaches to the procedure for conducting risk assessment, a matrix for assessing the risks of ignition of electric vehicles was formed. The resulting matrix of risks of electric cars catching fire demonstrated and confirmed the following: the risk of catching fire of electric cars and other similar vehicles in the overwhelming majority can be attributed to three degrees of probability (very low, low and high; the lack of filling in a significant number of cells of the matrix indicates the urgent need for a detailed analysis of each case of fire electric cars with the most clear definition of the cause of ignition. The specified research results, respectively, are a prerequisite for further research and improvement of the resulting risk matrix of electric vehicles.

ANALYSIS OF RESEARCH ON THE NEGATIVE INFLUENCE OF HEAT FLOW FROM THE FIRE CENTER ON THE SURROUNDING OBJECTS

A. M. Dominik — 2024-12-30

The development of the technical process creates new fire hazards. Along with this, much rescuers’ attention is focused on the processes of development and spread of combustion. But the issue of the thermal effect of fire requires no less attention. The phenomenon of thermal irradiation of the environment promotes the acceleration of the process of combustion spread. This creates a hazard factor for people around, because when such radiation is exposed to unprotected parts of the human body with a certain value, skin lesions, burns, etc. can occur. The purpose of the study is studying the process of heat propagation from a fire plume depending on various circumstances and factors. The method of analysis is based on well-known scientific studies of the negative impact and methods of protection against heat flows. Theoretical aspects were used to conduct the research, including the analysis of known publications and experimental results. It has been found that the issue of the negative impact of thermal effects has been considered and studied in many works by different authors. The present work analyzes and presents the research of scientists on the propagation of heat fluxes, the damage caused by thermal load, as well as mathematical modeling of thermal processes. Moreover, the protective properties of the water curtain created by the sprayed jet of a fire hose are studied. Despite a significant amount of research on the heat transfer process, the issue of protecting or reducing the heat load remains open and has not been fully explored. Thus, researchers have paid much attention to the process of damage to buildings and structures from the negative effects of heat. Less attention has been paid to the study of heat load and reduction of heat flow power. However, the protection of fire and rescue equipment used directly in the vicinity of the fire remains forgotten. All this causes damage to the vehicle and possible further ignition. The research has shown that scientists have done a lot of work to study the dependence of changes and negative effects of thermal radiation. However, the issue of protecting firefighting equipment during emergency response from this hazard remains unaddressed, which sometimes creates a hidden and additional danger to personnel. That is why, based on the analysis of research, the need for research and implementation of appropriate innovative protection technologies has been established.

SYNTHESIS OF A TWO-MASS SYSTEM OF SUBORDINATE REGULATION OF THE FIRE LIFT WORKING PLATFORM BY ROTATION BASED ON FRACTIONAL CONTROLLERS

A. P. Kushnir — 2024-12-30

The design of the boom of the lifting mechanism of the fire lifts is not absolutely rigid. As a result, elastic vibrations of the working platform occur. These oscillations negatively affect the operation of the automatic control system for moving the working platform, thus complicating the work of rescuers. For the safe and effective performance of rescue operations and extinguishing fires at height, the system of automatic control of the rotation of the working platform must damp elastic oscillations, ensure high speed, smooth acceleration and braking of the engine, static and dynamic accuracy of reproduction of given trajectories, absence of overregulation in transitional modes, etc. In this article, it is proposed to synthesize a positional system of subordinate regulation by rotation the working platform, taking into account the elastic properties of the boom. The synthesis of the system control is carried out by the modernized method of the generalized characteristic polynomial by applying a certain desired form of the fractional order. This will allow ensuring the simplicity of expression and the necessary dynamic and static characteristics of the movement of the working platform under the conditions of controlling and disturbing influences acting on it. This will make the work of rescuers safer and more efficient. A comprehensive method was used to conduct the research, which includes: theoretical mechanics and the theory of automatic control, namely, the synthesis of automatic control systems. To study the effectiveness of the proposed system of subordinate regulation, digital simulation in the Simulink package of the MATLAB software environment was used. To carry out the synthesis of the system of subordinate regulation, it is necessary to have a mathematical model of the control object. Since the boom of the fire lifts is not completely rigid, it can be represented by a two-mass system based on the Lagrange equation. The work presents a three-loop two-mass system of subordinate regulation of the rotation of the working platform. On the basis of the modernized method of synthesis of the generalized characteristic polynomial, a structural-parametric synthesis of this system of subordinate regulation was carried out. For this purpose, controllers of the angular speed of the motor, working platform and position were synthesized based on the proposed desired fractional form. In the Simulink package of the MATLAB software environment, a study of a synthesized three-loop two-mass system of subordinate regulation of the rotation of the working platform was carried out on a digital model. The application of the modernized method of synthesis of the generalized characteristic polynomial for the positional three-contour two-mass system of subordinate regulation of the rotation of the working platform by applying the given compact desired form of the fractional order is extended. The desired form of the fractional order provides a wide range of specified dynamic characteristics. This made it possible to carry out a structural and parametric synthesis of this system. As a result, the controllers of the angular speed of the motor, the working platform and the position for the entire three-loop system of subordinate regulation were synthesized on the basis of the proposed desired fractional form. As a result, the transient process of the initial position coordinate with the synthesized position controller provided a rise time of t0.95 = 4.273 s without overregulation, and the integer complex automatic position control system provided a rise time of t0.95 = 4.423 s, respectively. Thus, with the new controller, a gain in speed of approximately 5% was obtained.

WAYS TO IMPROVE THE EFFICIENCY OF EXTINGUISHING FIRES IN ATTIC ROOMS

V. I. Lushch — 2024-12-30

Due to current trends in construction, we can observe an increase in the number of residential buildings without full floors, which are equipped with attics. Attics can have different sizes and designs, ranging from small corners under the roof to large, spacious rooms. They are equipped with windows or hatches for lighting and ventilation, as well as have different heating and air conditioning systems, depending on local conditions and the purpose of the room. Fires in attic rooms can be especially dangerous due to limited access and difficult conditions for extinguishing. Such fires are often difficult to spot, and fire can spread rapidly through wooden roof structures and other combustible materials that may be in the attic. Thus, the design features of buildings with attic rooms require new approaches and tactics to effectively extinguish fires that may occur in them. To achieve this goal, an analysis of domestic and international sources was carried out, determining the procedure for extinguishing fires in attic rooms. The necessary fire-technical and rescue equipment, and methods of extinguishing fires in buildings with attic rooms were also considered. To achieve this goal, an analysis of domestic and international sources was carried out, determining the procedure for extinguishing fires in attic rooms. The necessary fire-technical and rescue equipment, and methods of extinguishing fires in buildings with attic rooms were also considered. As a result of the work carried out, it is established that domestic governing documents and scientific works regulating the need and procedure for extinguishing fires in the residential sector do not fully (superficially) reveal the essence of extinguishing fires in buildings with attic rooms. On the basis of the carried out analysis of methods of extinguishing fires in such premises, as well as types and ways of gas exchange during a fire in the fence, one of the alternative methods of extinguishing trunks with punches was determined, which provide effective containment and elimination of fire in attic rooms. The article analyzes domestic and foreign sources regulating the procedure for organizing fire extinguishing in attic rooms in the residential sector, analyzes the necessary fire-technical, rescue equipment and methods of extinguishing fires in attic rooms. A methodology has been developed that would regulate the procedure for extinguishing attic rooms under the most difficult conditions, a graphical designation of the punch barrel with nozzles for extinguishing and protection has been proposed.

INFLUENCE OF ORGANOMETALLIC COMPLEXES ON THE COMBUSTIBILITY AND SMOKE-FORMING ABILITY OF POLYMERIC MATERIALS BASED ON EPOXY RESINS

P. V. Pastuhov — 2024-12-30

One of the characteristic features of combustion and smoldering of polymeric materials, including materials based on epoxy resins, is the high intensity of smoke formation and the release of a large number of toxic products. This has a negative impact not only on the environment but also on the human body. According to statistics, almost 70% of fatalities in fires are caused by poisoning from toxic products of thermal decomposition and combustion of combustible materials. Therefore, research aimed at finding new effective substances to reduce the combustibility and smoke-forming ability of polymeric materials that would meet modern requirements is extremely relevant. To obtain new organometallic complexes and to reveal the regularities of their influence on the combustibility and smoke-forming ability of epoxy polymers during flame combustion and smoldering. Organometallic complexes and metal-coordinated epoxy-amine composites were obtained by direct interaction of the corresponding components. The combustibility of the epoxy-amine composites was evaluated according to DSTU 8829:2019 (p. 7.3), and the smoke-forming ability – according to DSTU 8829:2019 (p. 7.19). A technology for the preparation of organometallic complexes and metal-coordinated epoxy-amine composites has been developed. The influence of the synthesized organometallic complexes on the combustibility group indices, the intensity of smoke emission during flame combustion and smoldering of epoxy-amine composites was investigated. It has been established that in terms of reducing the combustibility and smoke-forming ability of epoxy-amine composites, [Cu(eda)2(H2O)(Cl)]Cl is less effective than [Cu(eda)2(H2O)(F)]F. It was found that the introduction of [Cu(eda)2(H2O)(F)]F into the epoxy-amine composite leads to a decrease in the maximum temperature increase, a decrease in the mass loss of the composite samples due to combustion, and an increase in the time to reach the maximum temperature of gaseous combustion products, and makes it possible to obtain diffical-to-combustible polymeric materials. It was proved that [Cu(eda)2(H2O)(F)]F proved to be an effective smoke suppressant additive and provided a decrease in the smoke formation coefficient in the flame combustion mode by 38–52%, and in the smoldering mode by 45–63%. It has been established that materials based on modified [Cu(eda)2(H2O)(F)]F epoxy-amine composites according to DSTU 8829:2019 meet the requirements of group D2, i.e., are materials with moderate smoke-forming ability. The prospects of using organometallic complexes to reduce the combustibility and smoke-forming ability of polymeric materials based on epoxy-amine composites have been proved. This can be explained by an increase in the yield of carbonized residue, intensification of the combustion process of non-volatile decomposition products, as well as a change in the features of the thermo-oxidative degradation process in the direction of increasing the concentration of non-combustible gaseous products.

IMPROVEMENT OF THE CALCULATION METHOD FOR DETERMINING FIRE DISTANCES FOR WIND POWER PLANTS

D. V. Seredа — 2024-12-30

Existing building regulations determine the requirements for minimum fire distances between buildings and structures, taking into account the distance between external walls and other adjacent structures. For external energy installations, such as wind turbines, these requirements are set partly in industry regulations, but to a greater extent they are aimed at compliance with sanitary requirements. For example, they should be located at least 1 km from residential buildings and at a distance of at least three diameters of the rotor blades from neighboring objects. However, the existing regulations do not fully take into account the potential risks of the occurrence and development of fires at wind power plants, especially in case of destruction of their structure. Thus, there is a task regarding the need to improve the method of determining fire protection distances, taking into account the design parameters of wind power plants and possible fire development scenarios. The purpose of the work is to determine ways to improve the method of establishing fire-fighting distances from wind turbines to adjacent objects, taking into account their potential fire hazards. The work used the methods of generalization of previous studies on the analysis of the method of determining fire protection distances between objects, the method of analytical research, as well as the methods of comparison and analogy. An analysis of potential fire-hazardous and emergency situations accompanied by the destruction of wind power plants was carried out; the factors affecting the accuracy of determining fire protection distances depending on the types (power) of wind power plants are determined; the methodology of determining safe fire distances was investigated and ways of its improvement were identified; criteria are defined that can characterize the conditions of compliance with fire safety in terms of fire protection distances. The most unfavorable conditions for the spread of fire to adjacent objects from wind power plants have been determined, which consist in the possibility of mechanical destruction of such power plants, which, as a result, can lead to a decrease in the established fire protection distances and cause the fire to spread to the adjacent object. The technical parameters of wind power plants are systematized, taking into account the dependence on the proportional increase in their height, power and the amount of fire load in the middle of their housing, which can significantly affect the accuracy of determining fire protection distances. It is proposed to increase the accuracy of forecasting the limitation of the spread of fire between adjacent objects in the event of emergency situations caused by mechanical damage to wind power installations, which is accompanied by the occurrence of fire, to take into account the value of the height of the support of the wind power installation, the area of oil spillage, which is formed as a result of the destruction of oil-filled assemblies and units.

DETERMINATION OF FIRE POINT BINARY LIQUID SOLUTION

O. S. Chernenko — 2024-12-30

Very little attention is paid to the study of fire point. One approach used to find the analytical condition forfire point is to fit between the saturated vapor pressure and the stoichiometric value of the pressure. However, different authors for different classes of individual organic compounds identified “characteristic” values of this ratio from 0.6 to 1.5. Similar studies were not conducted for binary solutions. The purpose of this work is to investigate the influence of the stoichiometric ratio between steam and oxygen and changes in the composition of binary mixtures on their fire point. In this work, analytical dependences of fire point binary solution from his properties are proposed, which are based on the physicochemical properties of the solution components (heat of vaporization, its temperature dependence, critical temperature and boiling point). An aqueous solution of a flammable liquid and a solution of two flammable liquids are considered separately. The basis of the analytical formula is the assumption that at the moment of liquid ignition near its surface, mass fractions vapor of the light summer liquid and the oxygen of the air is stoichiometrically. The decrease in vapor concentration near the surface of an aqueous solution is taken into account by Raoult’s law. When evaluating fire point of binary solutions there are two cases: fire points of the solution components 1) is significantly different or 2) close. In the first case, it can be assumed that a one component difficult evaporates. And therefore it can be called an inert component. However, this assumption is worse when his part is more than 50%. In the more general case, simultaneous participation of both pairs in droplets ignition is assumed and stoichiometry is assumed to be allowed for each vapor. The agreement of the obtained dependence with the available experimental data on aqueous solutions of acetone, methanol, ethanol, and propanol, as well as solutions of n-octane/n-decane and ethanol/butanol is observed. This allows us to state that the assumption of achieving stoichiometry for a vapor of each mixture component is acceptable.

INFORMATION ABOUT THE AUTHORS

M. Sorochych — 2024-12-30