Fire Protection Efficiency Research Articles

Increasing the Fire Protection Efficiency of Metal Building Structures

Проаналізовано вітчизняні та зарубіжні вогнегасні покриття та особливості їх використання як елементів пасивного та активного вогнезахисту з матеріалами, що спучуються, а також оцінено доцільність їх застосування для будівельних конструкцій з металевими елементами для підвищення вогнестійкості будівлі та споруди промислового сектору. Отримано залежності, які дають змогу прогнозувати безпечний час перебування людей всередині об’єкта до обвалення будівельних конструкцій у разі виникнення пожежі. Розглядалися можливості виробництва з використанням ряду недорогих композицій, які набухають і підвищують вогнестійкість будівель з металевими елементами за рахунок набухання та адгезії до горючих поверхонь металоконструкцій. Були проведені експерименти для отримання даних про можливість безпечного перебування людей всередині будівлі або споруди до їх руйнування. Встановлено, що набухання та зчеплення з поверхнями металевих конструкцій дозволяють підвищити пожежну безпеку особового складу пожежно-рятувальних та інших служб, залучених до ліквідації таких надзвичайних ситуацій.

Impact of Jet Fires on Steel Structures: Application of Passive Fire Protection Materials

Jet fires are the second most common fire scenario after spill fires. This type of fire is characteristic of gas and gas–oil fires occurring on oil platforms and gas production and processing plants. The consequences of such fires are characterized by high material damage; this is associated with extensive networks of technological communications, since there is a high density of technological facilities and installations in the territory where these fires occur. At such facilities, there is a large number of steel structures, which under the action of high temperature quickly lose their strength and deform. To protect steel structures in the oil and gas industry, fire protection is used, which consists of different types: boards in the form of flat plates, plasters, and epoxy paints. This paper compares three types of fire protection materials for steel structures under jet fire: board fireproofing, plaster composition, and epoxy coating. When comparing the efficiency in jet fire, cement boards were found to be the best. However, despite the better fire protection efficiency, their low application is expected due to their massiveness and the high cost of such protection and the difficulty of installation. Nevertheless, the development of fire depends on the place of its origin, the size of the initial fire zone, and the stability and massiveness of the metal elements of the vessel structure or the structure of the boards on which the equipment can be placed. Therefore, it is necessary to take these factors into account when selecting fire protection and to apply it depending on the required fire resistance limits of structures, which should be determined depending on the fire development scenarios.

FEATURES OF FIRE PROTECTION TREATMENT OF LOAD-BEARING BUILDING STRUCTURES

The article emphasizes that wood is a flammable material, flames spread quickly, which poses a threat to building structures. Therefore, it must be protected by effective means of fire protection. Regulatory and technical documentation is presented, which establishes requirements for the quality of fire protection of wooden structures. Using the example of state reserve enterprises, it is shown that there are many methods of fire-resistant treatment of wooden structures with flame retardants. Among them are the impregnation of wood with inorganic salts and the application of coatings on an organic basis. These include impregnation of wood with inorganic salts and application of coatings on an organic basis. It is shown that the specified methods of processing have disadvantages during application and operation, which include the moistening of wood under the influence of external natural factors, which leads to the dissolution and leaching of salts, increased smoke formation, and the formation of toxic combustion products. The constituent parts of the intumescent coating are proposed and their effectiveness in relation to fire protection of wood is determined. Depending on the content of PVA-dispersion, a change in the coefficient of swelling was determined, which is in the range from 14.3 to 25.1. Thus, it was determined that when mineral fillers are added to the composition of the organo-mineral composition in the amount of 10%, it helps to increase the coefficient of swelling from 30 to 36.7, which is 1.5...1.84 times greater than the value of the coefficient of swelling of the optimal composition of the organo-mineral composition without fillers. The article presents research on the creation of fire-resistant intumescent coatings capable of providing a wide range of fire-resistant and operational properties. After testing samples treated with an intumescent coating, under the action of a burner flame, a sample weight loss of no more than 6% was obtained, and the temperature of flue gases did not exceed 184ºС, which refers the treated wood to the group of non-combustible materials. Thus, the intumescent coating provides the first group of fire protection efficiency. Keywords: building structures, fire-resistant treatment, state reserve enterprises, intumescent coatings, fire-resistant properties, efficiency.

PROBLEMATIC ASPECTS OF DETERMINING FIRE PROTECTION OF WOOD

Annually, fires inflict huge losses to both business entities of various forms of ownership and the state overall. According to analytical data for nine months of 2023, 2212 fires occurred in Ukraine at objects of different forms of ownership subject to state supervision (control) in technogenic and fire safety. Many researchers confirm that fire protection of wood is an effective prophylactic measure. However, there are significant factors influencing the reduction of its efficiency directly and also factors that do not affect the efficiency of fire protection directly but provide an objective determination of the quality of fire protection. One of the factors in objectively determining the quality of fire protection is verifying the fire protection compliance. This study aims to determine the causes and patterns of improper fire protection of wooden building structures with fire-retardant solutions (lower than stated in the manufacturer’s regulations). The analysis of recent research and publications shows that the issue of verifying the compliance of fire protection of wooden structures directly after the works in Ukraine has not been studied. Many modern fire protection solutions on the Ukrainian market require improved quality control methods. The existent system of verification of the compliance of fire protection has substantial defects and does not give a possibility to define objectively the quality of fire protection. Precise terminology is absent in normative acts, the methods described for verifying fire protection are not up-to-date, and the regulatory documents for fireproof solutions, in most cases, do not contain the necessary information for quality control. Improvement of verification of the compliance of fire protection of the exploited wood is a necessity at all stages, beginning from determining correct terminology and actualisation of the Rules of fire protection to developing effective methods of verification taking into account the features of modern fireproof solutions. Keywords: fire protection of wood, fire protection compliance verification, fire protection rules, wood impregnation.

Development of test methods for fire-retardant coatings of steel engineering structures during operation

Introduction. Prediction of the durability of flame-retardant coatings of steel engineering structures and preservation of their performance during operation remain important research directions. There is a lack of normative documents in the field of fire protection, regulating the process of testing of flame-retardant coatings during operation, as well as determination of their durability (service life).Aim. To develop test methods for determining the resistance of flame-retardant coatings of steel engineering structures exposed to climatic factors, preservation of their fireproof and anti-corrosion properties during operation.Materials and methods. Test specimens included 600 x 600 x 5 mm plates made of 08kp and 08ps sheet steel according to State Standard 16523-97 and State Standard 9045-93 with a flame-retardant agent applied on the front side.Results. Methods for testing thin-layer intumescent and structural flame-retardant coatings during operation are proposed. The methodology of accelerated climatic testing of specimens coated with thin-layer intumescent flame-retardant coatings (flame-retardant paints) corresponds to State Standard 9.401-2018. These coatings are inherently high-solid paint materials. A new methodology, sequence, and modes of testing are developed for structural flame-retardant coatings. The subsequent assessment of fireproof properties of coatings and their preservation is carried out by the methods of fire protection efficiency according to State Standard R 53295-99 and the methods of thermal analysis. These methods imply comparison of the characteristics of the initial flame-retardant coating and those obtained after sample aging. The preservation of fireproof properties by thin-layer intumescent and structural coatings is additionally evaluated by the intumescence coefficient and the change in thermal conductivity, respectively.Conclusions. Test methods for flame-retardant coatings of steel engineering structures during operation are developed. Threshold levels of changes in their properties are established. After accelerated climatic tests, fire protection efficiency should not decrease by no more than 20 %. For structural fire protection, an increase in thermal conductivity by no more than 5 % is permitted. For thin-layer coatings, the arithmetic mean value of the intumescence coefficient should not decrease by no more than 30 % of the initial value.Implications. The developed methods were used in the preparation of a draft national standard of the Russian Federation “Steel engineering structures with fireproof coatings. Test methods for anticorrosion properties and resistance to climatic factors during operation” to ensure regulatory fire safety requirements for these structures.

Thermal Characteristics of Epoxy Fire-Retardant Coatings under Different Fire Regimes

Different systems of fire protection coatings are used to protect the metal structures of stories and trestles at oil and gas facilities from low (when filling cryogenic liquids) and high temperatures (in case of the possible development of a hydrocarbon fire regime). This paper presents the results of experiments of fireproof coatings on an epoxy binder after the simulation of a liquefied hydrocarbons spill and subsequent development of a hydrocarbon fire regime at the object of protection and exposure of structures to a standard fire regime. According to the experimental results, the temperatures on the samples at the end of the cryogenic exposure were determined and the time from the beginning of the thermal exposure to the limit state of the samples at a hydrocarbon and standard temperature fire regime was determined. As a result, temperature–time curves in the hydrocarbon and standard fire regimes were obtained, showing good convergence with the simulation results. The solution of the inverse task of heat conduction using finite element modeling made it possible to determine the thermophysical properties of the formed foam coke at the end of the fire tests of steel structures with intumescent coatings. It was determined that an average of 12 mm of intumescent coating thickness is required to achieve a fire protection efficiency of 120 min and for the expected impact of the hydrocarbon fire regime, the coating consumption should be increased by 1.5–2 times compared to the coating consumption for the standard regime.

A novel IoT-based framework with Prognostics and Health Management and short term fire risk assessment in smart firefighting system

In recent years, “smart firefighting” becomes a popular research topic which aims at improving the efficiency of fire protection and safety. However, in existing smart firefighting systems: (1) state and analog firefighting IoT data is not fully utilized; (2) fire risk assessment requires a long time to update; (3) few existing works can recognize faults and forecast potential risks with both temporal and spatial information from multiple IoT sensors. Therefore, a novel framework is proposed to solve the above problems as follows: (1) Short-term Fire Risk Assessment (SFRA) is proposed by considering the working status, maintenance and rectification performance of firefighting facilities based on IoT state data; (2) Prognostics and Health Management (PHM) algorithms are applied in the fire safety field for the first time to detect faults and forecast potential risks with temporal and spatial information with IoT analog data from single or multiple sensors. A case study is carried out in a building in Shanghai and a smart firefighting system is deployed with the edge computing gateway. The experimental results of the SFRA and PHM are presented and analyzed in details. The performance evaluation and comparison results are presented with multiple metrics. The reliability of the proposed framework is discussed. The case study concluded that the proposed framework extends the utilization of IoT data, improves the efficiency of fire risk assessment and enhances the accuracy of faults detection and potential risk forecast. Moreover, the deployed firefighting system improves the data privacy and computational efficiency.

Improving the fire resistance of wooden structures by a combined method

The flammability of wood largely limits the use of wooden structures in modern construction. Therefore, there is a need to protect the wooden structures of buildings and structures from fire danger. Ammophos-A, ammonium sulfate, expanded perliteб and epoxy were used to develop the fire-retardant surface coating. The experiments were carried out by changing the amount of one of these components in the composition, leaving the others constant. At the same time, fire hazard indicators were controlled parameters. In this way, the optimal ratios of the components of the flame-retardant composition were established, which were: 15:15:10:50 (wt.%), respectively, ammophos-A, ammonium sulfate, expanded perlite, epoxy resin, further designated flame retardant AS-143. The test parameters of structural samples treated with this flame retardant at a consumption of 400–500 g/m2 were: weight loss 4.0–5.0 %, flame burning time 11–18 s, flameless 19–23 s. The effectiveness of the flame retardant AS-143 was established in comparison with flame retardant No. 13, which, according to the weight loss of the samples, was 43.2 %. The essence of the results is explained by the correct selection of chemical compounds and their component ratio in the fire-retardant composition, which exhibit a synergistic character during the combustion of wooden structures. At the next stage, in addition to surface treatment of wooden structures, they were faced with fire-resistant plasterboard sheets. Fire tests were carried out under field conditions for 30 minutes, the results of which were: the length of flame propagation over the surface of the samples was 456–678 mm; flame propagation speed 0.015–0.023 m/min. The data indicate that wooden structures treated in a combined way belong to group I of fire protection efficiency. These structures can be safely used in buildings and structures, especially with enclosing, attic, or attic types

Fire protection of wooden building structures

The paper covers the issues of fire protection of cellulose-containing materials, in particular wood. It is shown that despite a number of valuable properties that wood possesses, it is a rather flammable material by its composition. It is known from the literature that one of the most important steps in protecting wood from fire is fire protection treatment. It is carried out in two main ways: surface treatment (applying special compounds to the wood surface to form a fireproof layer) and deep impregnation of wood with flame retardants. For the fire protection of OSB samples, a water-based intumescent paint consisting of a system of flame retardants in combination with fillers, pigment, and functional additives was developed. The research was conducted using analytical and experimental methods, which consist of analyzing and studying the provisions of national standards that describe the method for determining the flammability group of substances and materials and the method for determining the fire protection efficiency of fire retardants. The experimental part of the study involved the manufacture of test samples, application of fire retardants to them, recording the temperature of gaseous combustion products, the maximum temperature increase, the time interval for reaching the maximum temperature, the weight of the samples, and the weight loss of the samples. The research methodology states that the wood samples were tested in accordance with DSTU 8829 at the OTM installation. It also provides means for measuring the flue gas temperature, test time, and determining the mass loss of samples before and after testing. The test results showed that the developed fire retardant based on intumescent paint provides a group of refractory materials in accordance with DSTU 8829, i.e., the wood protected by this method belongs to refractory materials, namely: the flue gas temperature does not exceed 260˚C, the mass loss of samples after testing is not more than 60%.

Исследование влияния температурного режима пожара на эффективность вспучивающегося огнезащитного покрытия, предназначенного для огнезащиты стальных конструкций

Introduction. The usage of intumescent coating (hereinafter referred to as IC) is justified by the development of a fire protection project, taking into account the data on its fire protection efficiency, estimated under the influence of standard temperature conditions, the usage of which can lead to overestimating the fire resistance margin in the project or underestimating the thermal impact on the steel building structures with IC fire protection in conditions of a real fire. Aims and purposes. The purpose of the study is to evaluate the effect of fire temperature conditions on the effectiveness of IC. To achieve this goal, the following tasks were carried out: a temperature mode of fire in a building under different fire loads by the example of a warehouse building was estimated; experiments to estimate the influence of different heat fluxes, reduced thickness of metal and IC thickness on its effectiveness by the full factor experiment of the type 2 were conducted. Methods. To mathematically simulate real temperature fires, the Fire Dynamics Simulator (FDS) software package, which implements a field (differential) mathematical model, was used. To study the effect of the obtained fire temperature regimes on the effectiveness of IC, experiments were carried out according to the plan of a complete factor experiment type 2. The test specimens were carbon steel metal plates with dimensions of 100 × 100 mm with reduced thickness of 3 and 4.5 mm and painted with 0.25 and 0.5 mm organic-based single-component IC. A radiant heat flux panel with a radiant heat flux density of 10 to 50 kW/m2 was used to assess the effects of heat flux. Results and discussion. In the course of numerical experiments in the FDS software package, it was found that the thermal impact on steel building structures during a fire can differ significantly from the standard temperature regime, both upwards and downwards. The results of the experiment showed that the heating time of the test samples had the greatest influence of the actors under consideration (the value of the heat flux, the reduced thickness of the metal, the thickness of IC) had the value of the heat flux, as the largest absolute value of the regression equation was obtained. Conclusion. The assumption of possible underestimation of the thermal effect under “standard” temperature conditions on the fire resistance of steel building structures with IC fire protection was confirmed by the tests.

Studying the thermal characteristics and effectiveness of structural fire proofing made of PROSASK Firepanel cement boards by means of reproducing the high-temperature effect

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.

Simulation of nomograms showing the heating of steel structures with flame retardant coatings of different thicknesses (in the water)

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.

МЕХАНІЗМ СТРУКТУРОУТВОРЕННЯ СПУЧЕНОГО ШАРУ ПІНОКОКСУ ПРИ ВПЛИВІ МІНЕРАЛЬНИХ РЕЧОВИН

The studies have established the effect of fillers on the performance of the fireproof coating, the parameters of its swelling under the influence of temperature and inhibition, which makes it possible to influence this process. The effect of fillers on the coefficient of swelling of coatings based on inorganic and organic substances during thermal exposure was investigated. It isproved that it consists in the creation of a layer on the surface of the material that prevents heating to a critical temperature and decomposition of the material. Experimental studies have confirmed that the introduction of titanium oxide and aluminum hydroxide in the amount of 5% contributes to the achievement of the highest value of the coefficient of swelling - up to 47, which is 1.11 times higher than the value of the coefficient of swelling when aluminum hydroxide is introduced, titanium oxide and talc in the amount of 3.3%, 1.12 times higher than the value of the coefficient of swelling when titanium oxide and talc in the amount of 5% were added, and 1.08 times higher than the value of the coefficient of swelling when aluminum hydroxide and talc in the amount of 5% were added. The influence of fillers under the action of high-temperature heat flow on the change in the process of swelling of the fireproof coating was established and the mechanism of the kinetics of the fillers' action, characterized by a decrease in speed and mass loss, was determined. Thus, at 700 °C, the introduction of fillers leads to theformation of refractory compositions that prevent the burnout of the resulting foam coke, which increases the efficiency of fire protection of building structures. On the basis of physicochemical research methods, it is shown that the introduction of a mixture of titanium dioxide and aluminum hydroxide in the amount of 5% each into the composition of the organic-inorganic composition leads to an increase in the coefficient of swelling, orderliness of the structure of the foam coke layer, and an increase in its heat resistance due to the dehydration of mixed titanium-aluminum phosphates.

The Efficiency of Various Fire Protectants for Wooden Structures

The article deals with the scientific problem of the development and application of various fire protective compositions for wooden structures. Based on the results of theoretical and experimental studies, the authors for the first time attempted to state the influence of the chemical nature and mechanism of flame retardant action on the effectiveness of fire protection means. When assessing the effectiveness of fire protection, the authors paid special attention to the key parameters that determine the fire resistance of wooden structures. The possibility of developing effective fire protection systems, capable not only to provide a certain group of fire protection efficiency but also to influence the parameters of the charring process and the intensity of wood heating temperature is shown. Complex mechanisms of bloating (intumescence) and carbonization in combination with the mechanism of regulating the process of carbonization and wood carbonization, are able to provide the protected material with effective resistance to high temperatures (fire). The use of such types of fire protection allows forming an independent scientific direction associated with the development and use of fire protection systems contributing not only to the effective reduction of fire danger of wood and materials based on it but also to increasing the fire resistance of wooden structures.

Flame Protection Technologies for Wood: Developing and Testing for Fire of Timbers with a Flame-retardant Coating Based on the Epoxy-amine Composite Modified by Copper(II) Hexafluorosilicate

A new type of fire-retardant coating for wood based on epoxy-amine composites modified with copper(II) hexafluorosilicate has been developed. To optimize the composition of the fire-retardant coating, the values of ignition and self-ignition temperatures, the combustibility group indices and the smoke generation coefficient of the developed epoxy-amine composites were used. It was found that the values of the ignition and self-ignition temperatures of epoxy-amine composites containing a flame retardant are higher than those of composites without it, by 15–34 °C and 25–58 °C, respectively. Compared to unmodified epoxy-amine composites, CuSiF6-modified epoxy-amine composites have 204–327 °C lower values of the maximum temperature of combustion gases and 7.8–10.4% less mass loss during combustion. It is shown that modified epoxy-amine composites with an optimized composition are classified as hardly combustible materials with moderate smoke-forming ability. Based on the results of experimental studies, the technological mode of coating the wood was chosen. The developed epoxy-amine composite with reduced combustibility has been used as a fire-retardant coating for wooden structures. Testing for fire showed that developed coating belongs the first group of fire protection efficiency, which ensures reliable fire protection of wood. In contrast, the coatings based on epoxy-amine composites without a flame retardant do not provide fire protection of wood at all.

ПОРІВНЯННЯ ПОЛІОЛІВ ЯК КАРБОНІЗУЮЧИХ АГЕНТІВ ВОГНЕЗАХИСНИХ КОМПОЗИЦІЙ ІНТУМЕСЦЕНТНОГО ТИПУ

Purpose. To study the influence of the carbonizing agent structure on the formation of thermal insulating char layer of intumescent system acid donor/polyol and on the fire protection efficiency of the system at high temperatures. Methodology. A fire retardant mixture of an acid donor (phosphates ammonium, urea, melamine)/ polyol was chosen as a model intumescent system. Dispersion of vinyl acetate copolymer with ethylene was used as a polymeric component. The study applied the characteristics of the char layer of the intumescent composition at a certain temperature. The volumetric intumescent coefficient (K, cm3/g), mass of char residue (m, %), structure and density of the char layer are proposed as the main estimated parameters of flame retardant effect. IR spectroscopy was used to identify products of thermolysis of intumescent systems. Determination of fire protection efficiency of intumescent coatings was carried out in a mini-oven under standard fire conditions. Findings. The influence of polyol structure on the formation of thermal insulating char layer of intumescent acid donor/polyol system and the prediction of fire protection efficiency of this system under high temperature conditions has been investigated. It has been shown that under conditions of thermal shock the fire protection efficiency is more dependent on the nucleophilic reactivity of the polyol towards the unsaturated phosphorus atom of the acid donor than on its thermal stability. It has been found that pentaerythritol, dipentaerythritol, starch, dextrin, xylitol and sorbitol are the most effective carbonizing agents, regardless of the structure of the acid donor. It has been proved by infrared spectroscopy that at high temperatures as a result of the decomposition of pentaerythritol one of the reaction products is the aldehydes interacting with pentaerythritol with the formation of oligomeric compounds with a simple ether bond C-O-C. At the same time, pentaerythritol can be considered as a universal source of carbon framework for intumescent flame retardants regardless of the phosphate structure used. Originality. It has been shown that an important factor to increase the fire protection efficiency of intumescent systems is the use of polyols with an increased nucleophilicity in the esterification between polyol and phosphoric acid.Practical value. The optimal polyols as carbonizing agents for formulation of intumescent coatings with enhanced fire protection properties have been determined.

ПОРІВНЯННЯ АМІНІВ ЯК ГАЗОУТВОРЮВАЧІВ ВОГНЕЗАХИСНИХ КОМПОЗИЦІЙ ІНТУМЕСЦЕНТНОГО ТИПУ

Purpose. Study of influence of blowing agents amines structure on the construction processes of thermal insulating char layer of intumescent system ammonium polyphosphate/pentaerythritol/amine and fire protection efficiency of this system at high temperatures. Methodology. A fire retardant mixture of ammonium polyphosphate/pentaerythritol/amine was chosen as a model intumescent system. Dispersion of vinyl acetate copolymer with vinyl ether of versatic acid was used as a polymeric component. A step-by-step study of the characteristics of the char layer of the intumescent composition was applied in the study, consisting in the analysis of the characteristics of the char formed after keeping the intumescent composition samples at a certain temperature between 100 and 800 °C, char residue mass (m, %), structure and density of the formed char layer. The method of infrared spectroscopy was used for identification of products of thermolysis of intumescent systems. Determination of fire protection efficiency of intumescent coatings was carried out in a mini-oven under standard fire conditions. Findings. The influence of the structure of amines blowing agents on the formation of char layer of intumescent system ammonium polyphosphate/pentaerythritol/amine was studied. Physico-chemical parameters of char layer formed during high temperature swelling of intumescent system components with varying amine: urea, melamine, dicyandiamide, guanidine, thiocarbamide, formylthiosemicarbazide, thiosemicarbazide, phenylethylcarbamide have been determined. In the temperature range 200–400 oC for systems with linear amines (urea, thiocarbamide, thiosemicarbazide), there is a rapid formation of insulating layer with intense outgassing (high intumescent coefficients K) and the same rapid its destruction with significant losses of char residue mass (Δm). The presence of melamine, dicyandiamide and guanidine in intumescent system provides constancy of intumescent coefficient at minimal mass loss. Chemical transformations of intumescent systems were studied by the method of infrared spectroscopy when the investigated amines were varied. It was found that linear diamines do not form stable spatially branched phosphamide compounds with phosphates as the basis of a thermostable heat-insulating frame. At the same time in IR spectra of char residue systems with melamine, dicyandiamide and guanidine the absorption bands of P-N-C bonds (1070–1050 cm-1) and P-N (980–950 cm-1) up to 600–700 oC are observed. Fire tests proved that melamine, dicyandiamide and guanidine are blowing agents providing maximum protection of metal against fire and can be used for composition of fire retardants for steel constructions.Originality. It has been proved that amines in intumescent polyphosphate system perform at least two functions: blowing agents by means of thermal destruction to incombustible gases and nucleophilic compound that takes part in char layer formation by aminolysis of electrophilic substrates.Practical value. The optimum amine blowing agents for developing formulations of intumescent coatings with enhanced flame retardant properties have been established.

ПІДВИЩЕННЯ ВОГНЕЗАХИСНОЇ ЕФЕКТИВНОСТІ ІНТУМЕСЦЕНТНИХ ЕПОКСИДНИХ ПОКРИТТІВ СПОЛУКАМИ ІНТЕРКАЛЬОВАНОГО ГРАФІТУ

Investigation of the effect of nitrate oxide graphite on the parameters of char layer, obtained from the system of ammonium polyphosphate / melamine / pentaerythritol / epoxy resin under the influence of temperatures of 200–800 °С. Methodology. A fire retardant mixture was chosen as a model intumescent system ammonium polyphosphate / melamine / pentaerythritol. As a polymer component was used bisphenols A / F epoxy resin together with a polyamidoamine hardener. Nitrate oxide graphite was obtained by oxidation of natural scaly graphite with fuming nitrogen acid. The effect of impurities of nitrate oxide graphite was determined by thermogravimetry on the intumescence coefficient of intumescent compositions and the mass of the char residue intumescent compositions in temperature range of 200–800 °С. Findings. The influence of nitrate oxide graphite on the characteristics was studied of char layer of epoxy intumescent system ammonium polyphosphate / melamine / pentaerythritol / epoxy resin. The study of thermal oxidative degradation was carried out intumescent compositions in the temperature range 200–800 °С. It was shown that intercalated graphite compounds increase the thermal stability of the formed char layer at temperatures > 600 °С. Determined intumescence coefficients and thermogravimetric analysis of modified intumescent systems was performed nitrate oxide graphite with different degrees of intercalation, in the conditions of 200–800 °С. It was established that the optimal parameters of the char layer are in terms of volume intumescence coefficient and mass of the char residue are provided by graphites, which contain 15–25% of intercalant in its composition. But the results obtained allow us to determine nitrate oxide graphite as a promising modifier of epoxy intumescent systems to increase its fire protection efficiency. Originality. The influence of degree of intercalation of nitrate oxide graphite was studied on the characteristics of char layer of epoxy intumescent system for the first time. Practical value. The optimal content of intercalant in nitrate oxide graphite was established for the development of formulations of intumescent epoxy coatings with increased fire retardant properties.

Design of copper salt@graphene nanohybrids to accomplish excellent resilience and superior fire safety for flexible polyurethane foam

Flexible polyurethane foam (FPUF) is the most commonly used polyurethane, but its highly flammable characteristics makes it ignite easily and release a lot of heat and toxic gases. Here, the effect of different forms of copper salt modified graphene (rGO@CuO, rGO@Cu2O and rGO@CSOH) on improving the fire protection efficiency and mechanical property of FPUF is explored. Hybrid FPUF is characterized by thermogravimetric analysis (TGA), cone calorimeter, thermogravimetric analysis/Fourier transform infrared spectroscopy (TG-IR), tension, compression, and falling ball rebound testing. Compared with pure FPUF, the FPUF/rGO@CSOH show a significant decreasement in reducing the heat release of FPUF, the PHRR and THR are reduced by 36.9% and 29.4%, respectively. While the FPUF/rGO@Cu2O demonstrate excellent smoke and toxic gases suppression in FPUF, the PSPR and TSR are reduced by 24.6% and 51.9%, and the COP and COY are also reduced by 51.9% and 55.3%, respectively. After adding the copper salt hybrid, the buffering performance of FPUF did not change. Fortunately, the tensile and compressive strength increase obviously. The flame retardant and smoke suppression mechanism of hybrid FPUF has also been studied. This article gives a effective strategy for the preparation of FPUF with outstanding mechanical property, flame retardant and smoke suppression properties.

Обеспечение пожарной безопасности упаковок и тары из древесины

The possibility of developing a methodology for conducting tests to assess flame retardness of packages for storing hazardous substances, materials, or products, as well as the use of the efficient integrated means of modifying wood for their manufacture is considered. The analysis of the basic principles of the methodology of testing the building structures and products of the current standards showed the fundamental possibility of assessing the level of protection of explosive substances, materials or products contained in the package from the effects of fire hazards in the time from the beginning of tests under standard temperature conditions to the occurrence of the standardized limit states. To carry out studies on the assessment of flame retardness of the wooden packages, the means were selected that ensure not only their fire protection, but also weather resistance and moisture resistance, as well as strength. Comparative experimental studies of flame retardness allowed to assess behavior of the wooden packages during complex processing, and to show the advantages of their use to ensure integrity, thermal insulation capacity and the possibility of long-term storage while maintaining the main operational properties. As a result, the principal possibility of using standard equipment and measuring instruments in accordance with GOST 30247.0—94 was established, the main criteria for the assessment of flame retardness were developed, the efficiency of fire protection, as well as the strength characteristics of a complex tool for its possible use in the manufacture of structural elements and wood products, were studied.