AFFF foam fire extinguishing by gas-permeated spreading and flame barrier with different foaming gases

Fundamental inefficiency of existing foam fire systems extinguishing tanks with oil and petroleum products having a volume of 5000 m3 or more is shown by methods of mathematical modeling. The required foam supply intensity and foam supply rate allowing effective fire suppression in large tanks with a volume of up to 20000 m3 are theoretically predicted. On this basis of theoretical conclusions, a new method of foam fire extinguishing in large fuel tanks has been developed. To obtain the required intensities and supply rates, fire extinguishing foam is formed in a special container with the use of solid-fuel gas generators. The theoretical predictions were confirmed in 21 full-scale successful experiments, in which fire suppresion system based on the new method was able to extinguish a fully developed gasoline fire in tanks with a volume of 5000 m3 and 20 000 m3 just for 30-90 seconds. The required amount of the foaming agent to extinguish a fire in a 20 000 m3 tank is only 450 liters, which is at least 100 times less than for traditional foam fire fighting Contribution of the authors: the authors contributed equally to this article. The authors declare no conflicts of interests.

Foam fire extinguishing is an effective and practical method of extinguishing oil fires. However, commonly used aqueous film-forming foams pose significant environmental challenges. To address this issue, this study focused on developing a nano-modified silicone foam (NMSF) by integrating environmentally friendly silicone surfactants with nanoparticles, hydrocarbon surfactants and foam stabilizers. Subsequently, experiments were conducted to evaluate its performance. The results showed that the ratio-optimized NMSF had a foam expansion ratio of 11.2 and a 25% drainage time of 281.8 s. The introduction of modified nano-silica effectively improved the foam, resulting in an average bubble diameter of 1.837 mm. The homogeneous distribution of bubble size contributes to improve the mechanical properties of the liquid film walls. The presence of modified nano-silica also significantly improves the stability of the foam at elevated temperatures. In thermogravimetric tests, the mass loss of NMSF is less than 30%, which is better than the comparison samples. The NMSF demonstrates exceptional fire extinguishing and burn-resistant effects by preventing rapid liquid drainage during fire suppression. Moreover, the primary by-product of NMSF is carbon dioxide, which does not decompose into toxic or hazardous substances. This confirms NMSF’s environmental friendliness and emphasizes its positive fire suppression capabilities.

Introduction. The destruction of foam films occurs when they reach critical thickness and lose the liquid phase as a result of syneresis and evaporation, which are rather difficult to slow down. We have proposed a method for increasing the stability of the fire extinguishing foam by means of replenishing the liquid phase through sprinkling.Methods. Foam stability was measured by the time of destruction of 25 % of the initial foam volume. The concentration of the foaming agent in the sprinkled solution varied from 0.5 to 6 %. Carboxymethylcellulose sodium salt (Na CMC) was used as a stabilizing additive. Field studies were carried out by feeding foam and solution from two AT-3,2-40 (43253)001-MS tank cars.Results and discussion. It has been established that the foam stability is influenced by the sprinkling intensity and the foaming agent concentration. Foam sprinkling with the solutions having low concentration of thefoaming agent leads to the washout of surfactants from the films that reduces the foam stability. The sprinkling intensity reduction boosts the foam stability due to the replenishment of the moisture lost through evaporation. The foam stability was maximal in case of sprinkling with a 2 % solution of the foaming agent, while the sprinkling intensity had no influence. An increase in the concentration of the foaming agent in the sprinkled solution led to a decrease in the foam stability. It is found that a smaller amount of the foaming agent is consumed to maintain the amount of foam through sprinkling than to replenish the destroyed amount through additional foam generation. It is shown that various stabilizing additives can be added to the foam in the process of sprinkling. If Na CMC is added to the solution exposed to sprinkling, the time of foam destruction goes up 3–5 times even in case of a non-recurrent sprinkling session. Field tests have confirmed the feasibility of adding stabilizing additives to the foam by means of sprinkling.Conclusions. The results of the research have shown the feasibility of co-feeding the foam and surfactant solutions, containing various stabilizing additives, in order to extinguish fires and generate stable foams.

Рассматриваются процессы, происходящие у борта резервуара во время тушения горючей жидкости пеной после того, как бóльшая часть зеркала жидкости покроется огнетушащим слоем пены. Приведен анализ двух случаев, необходимых для тушения оставшихся очагов горения у борта резервуара: охлаждения свободного борта резервуара до температуры, при которой нагретый пламенем борт перестает служить источником зажигания паров топлива, и понижения температуры горючей жидкости до температуры, при которой уже не происходит воспламенения горючей смеси. Для первого случая разработана математическая модель, описывающая изменение температуры при охлаждении борта резервуара в зависимости от времени, и получены с определенными допущениями аналитические решения. Предложено выражение, определяющее время тушения горючей жидкости, по которому с учетом имеющихся экспериментальных данных представлены расчетные значения коэффициента теплоотдачи. Для второго случая получено уравнение изменения температуры борта резервуара при охлаждении во время тушения горючей жидкости пеной.

PURPOSE. Increasing attention has been paid recently to applying high-expansion foam as means of localizing and eliminating liquefied natural gas spills flaming combustion. Scientific sources widely discuss the issues of foam expansion rate and elasticity, critical intensity of its supply and application rate. However, critical foam layer thickness is underestimated. At the same time one of the reasons for fire-fighting foam low efficiency is precisely the difficulty in providing required foam layer thickness. The purpose of this publication is to assess relationship between critical foam layer thickness and main parameters of localizing and eliminating liquefied natural gas flaming combustion. METHODS. Review of scientific works covering the issue of flammable liquids and liquefied natural gas foam fire extinguishment has been carried out. Methods for providing required foam layer thickness and determining foam fire extinguishing efficiency are analyzed. Results of researchers’ own experiments have been discussed, taking into account international and domestic experience in conducting similar studies. FINDINGS. Based on researchers’ own experimental data analysis, taking into account information from scientific sources, critical foam layer thickness assessment has been made for foams of various expansions used to localize and eliminate liquefied natural gas spills flaming combustion. Approximate foam layer thickness in centimeters should be at least a quarter of high-expansion foam expansion value. RESEARCH APPLICATION FIELD. The results obtained provide general understanding that to ensure efficiency of liquefied natural gas flaming combustion localization and elimination, it is necessary to ensure not only appropriate foam expansion and application rate, but also required foam layer thickness. The results can be used in scientific research and educational process, as well as by fire services and emergency rescue units in elimination of accidents accompanied by liquefied natural gas spills flaming combustion. CONCLUSIONS. Foam layer thickness is the key parameter for liquefied natural gas spills foam fire extinguishment and providing controlled burning technology. Depending on foam supply intensity the necessary condition for providing liquefied natural gas flaming combustion localization and elimination is to achieve or exceed critical foam layer thickness. Critical foam layer thickness depends on foam expansion ratio. As foam expansion ratio increases, critical foam layer thickness rises, its value can exceed two or more meters.

자동차의 엔진룸의 내부를 살펴보면 여러 가지의 장치 및 장비가 복잡하게 설치되어 있고 각종 오일 등의 인화물질을 포함하고 있어 재발화 가능성이 매우 높다. 또한, 폭발가능성도 높기 때문에 운전자나 탑승자가 보닛을 열고 엔진룸에 직접 분말 소화기를 분사하는 방식으로는 한계가 있다. 따라서 엔진룸 내부에서 화재를 감지하여 소화약제를 분사한 뒤, 화재를 진화하는 소화시스템과 엔진룸 내부의 고열에 견딜 수 있고, HFC-227ea를 포함하는 충분한 점성을 가진 폼 형태의 소화약제를 개발 및 시험하였다. 그리고 포소화약제가 가지고 있는 소화원리인 질식 및 냉각효과와 HFC-227ea가 가진 부촉매효과를 동시에 이끌어 내고, 소화 후에도 분말 소화기처럼 잔존물에 의한 2차 피해가 없는 맞춤형 소화약제를 개발하였으며, 차량을 이용한 충돌실험을 통하여 방출이 완료된 후에도 이물질 없이 소화약제를 제거할 수 있는 장점이 존재하는 실험결과를 획득하였다. Several complex devices and equipments are installed in the car's engine room, including various kind of oils or other flammable materials. So re-ignition is very likely to take place in it. In addition, it is restrictive for the driver or the occupant to open the bonnet and to spray the fire extinguisher in the engine room due to the high possibility of explosion. Therefore, a fire extinguishing system, which can detect a fire and inject the fire extinguishing agent to extinguish it, and fire extinguishing agents including HFC-227ea, which can stand the high temperature within the engine room and hold the viscosity sufficient to keep it in the kind of foam, were developed and tested. And the suffocation effect and the cooling effect come from the fire extinguishing principle of the foam fire extinguishing agent and the inhibiter catalyst effect come from the one of HFC-227ea was led simultaneously, and fire extinguishing agents without the secondary damage caused by residuals after the fire extinguishment like a case of the powder fire extinguishing agent, were developed. And experiments using a vehicle collision after the discharge is complete, foreign material can be removed without extinguishing the advantage that experimental results obtained.

Foam extinguishing agents are the most effective extinguishing agents for liquid fires. The search of relevant domestic and foreign commercial foam fire extinguishing agent patents found that most commercial foam fire extinguishing agent formulations contain urea. In order to understand the mechanism of urea’s influence and clarify the application parameters of urea-added aqueous foam in the fire extinguishing process, this research investigated the surface tension, foaming ability, foam stability, and fire extinguishing performance for alkyl polyglucoside and alkyl polyglucoside/urea foams. It is found that the addition of urea promotes the formation of surfactant micelles, resulting in a decrease in critical micelle concentration, while the surface tension and foaming ability of the alkyl polyglucoside solution are only moderately affected by the urea. Besides, urea significantly improves the fire extinguishing performance of alkyl polyglucoside foam and the influence of urea concentration on fire extinguishing time is remarkable. On the one hand, the enhanced extinguishing performance can be explained by the increase of foam stability. On the other hand, urea produces incombustible gases such as NH3 and CO2 under the action of the high temperature of the fire, which may improve the fire extinguishing performance by cooling effect and asphyxiation effect. The increase in expansion ratio and the foam flow rate are beneficial to shorten the extinguishing time. The research results can guide the design of foam extinguishing agents.

The cold spray test of water spray fire extinguishing system, compressed air foam cannon fire extinguishing system and combined fire extinguishing test were carried out based on a scaled platform. The cold spray test results show that most of the water spray will be directly incorporated into the compressed air foam, and the defoaming effect of the water spray on the compressed air foam is limited. The combined fire extinguishing test shows that the water spray fire extinguishing system and the compressed air foam fire extinguishing system can achieve effective fire extinguishing under different fire extinguishing sequence conditions, and the two fire extinguishing systems can be used simultaneously in dealing with transformer oil fire. The comprehensive cooling effect of the dual system is better than that of a single system. Combining the actual characteristics and requirements of the converter station, a combination strategy of fire extinguishing system that suitable for the converter station is further proposed.

Introduction. The results of a series of experiments on the interaction of fire extinguishing foam with various hydrocarbons are described, which make it possible to understand the processes that affect the extinguishing efficiency. Goals and objectives. The purpose of this work was to explain self-emulsification during mass transfer as a possible dominant factor in the process of contact destruction of fire-extinguishing foam by hydrocarbons. For this, the following tasks were set: - to experimentally establish the possibility of self-emulsification during mass transfer in contact of foaming agent solutions with hydrocarbons; - to show the relationship between the stability of the foam and the stability of the emulsion formed in the foam films; - to establish the effect of foam parameters (multiplicity) on the possibility of stabilization (or destruction) of foams under the action of the resulting emulsion. Research methods. The main research method in this work was to observe the stability of the foam on the surface of hydrocarbons at different temperatures. Results and discussion. The paper presents the results of experimental studies showing that the contact of solutions of the investigated foaming agents with hydrocarbons leads to the spontaneous appearance of an emulsion. In the case of using aromatic hydrocarbons, this process is more intensive than for saturated ones. For solutions of a foaming agent in the form of a thin film, the process of self-emulsification during mass transfer is significantly accelerated and can take place at room temperature. A stable emulsion, introduced into the foam, stabilizes it, and an unstable one destroys it. Low expansion foam is usually stabilized in contact with hydrocarbon. Medium expansion foam is destroyed even under the condition of thermodynamic stability of foam films. Conclusion. The experimental data obtained made it possible to propose a mechanism for the contact interaction of foam with a hydrocarbon, according to which a more stable foam on the surface of a hydrocarbon can be obtained by a foaming agent, which, in addition to foaming properties, is a good emulsifier. Keywords: fire extinguishing foam, hydrocarbon, oil product, contact destruction, self-emulsification during mass transfer.

The main goal of this research is the fabrication of halogen free, environmentally friendly fire-extinguishing powders using local mineral raw materials and the development of technological processes for producing highly efficient fire-extinguishing foam-suspensions on the basis of the produced powders. Fire-extinguishing powders are made by mechanical treatment and mixing of raw materials: zeolite, clay shale, perlite and ammophos. The process does not need introduction of expensive, halogen-containing, hydrophobizators and ensures the cost-effective production of fire-extinguishing powders. The obtained fire-extinguishing powders are characterized by high performance properties, high fire-extinguishing capacity and coefficient of atomic oxygen recombination. Thus, they are characterized both by homogeneous and heterogeneous inhibition of combustion processes. The efficiency of the produced powders is not inferior to that of standard powders of common production. In addition, in contrast to their traditional analogs they are halogen free, environmentally friendly and cheaper (1.2-2 times cheaper). The obtained powders, unlike the ones of conventional production, have good compatibility with water and foam. Our foam-suspensions are prepared just by mechanical mixing of fire-extinguishing powders with water and surface-active substances – foamers. The process does not require chemical treatment of materials. Thus, the developed technology is simple and cost-effective. The foam-suspensions produced on the basis of the obtained powders have higher heat capacity, permeability, wetting effect like water and foam and unlike them, they allow for homogeneous as well as heterogeneous inhibition of the burning process. Thus, the so produced foam-suspensions will have higher extinguishing effect than water, foams or powders, taken separately. Based on the above, it can be suggested that the produced powders can be used for extinguishing all types of fires, including large-scale ones in a combination with water and foams.
 Chemical Engineering Research Bulletin 21(2019) 58-64

In order to improve the fire extinguishing performance of foam fire extinguishing agents in nonpolar liquid fires, the application of alkyl amidopropyl betaine with different chain lengths in aqueous film-forming foam fire extinguishing agents was studied. The relationship between the structure of alkylamidopropyl betaine and surface tension, foaming property and foam stability was analyzed. On this basis, different foam fire extinguishing agent formulations were formed, and then the surface tension, foam performance and fire extinguishing performance of each formulation were tested. The results show that the alkyl chain of alkylamidopropyl betaine is directly proportional to the foaming property. The shorter the alkyl chain, the less oily the foam is and the better the foam’s anti-burning performance. The combination of alkylamidopropyl betaine with different chain lengths is conducive to comprehensive product foam performance and oleophobic performance to achieve the best fire extinguishing effect.

Combining the three-phase foam and simulated sea mud particle (SM-P: simulated sea mud particle) containing inert substances (SMTP: simulated sea mud three-phase foam) to engineer a new three-phase foam fire extinguishing material was a viable strategy to solve the problem of coal mine spontaneous combustion prevention and insufficient stability of mine fire extinguishing materials. Herein, based on constant temperature heating table and simulated coal spontaneous combustion fire extinguishing device, the experiments were conducted to evaluate the material properties. As expected, the SMTP-20 exhibited excellent stability (73.00 mins at 40 °C), which was 2.19 times that of ordinary three-phase foam (34.33 mins at 40 °C). The introduction of SM-P can also effectively reduce the thermal decomposition of powdered coal, the corresponding temperature of thermal decomposition peak value of raw coal was delayed 17.78 °C. The SMTP-20 could construct a thin fibrous-like foam layer with SM-P to cover the surface of burning coal and effectively seal cracks in the coal from oxygen contact, thereby preventing coal further oxidation. This work not only offers a new three-phase foam with outstanding performance, but also unravels a strategy for preparing three-phase foam with high stability and good fire extinguishing effect.

Military units and civil defense units have unused reserves of disinfectant, decontaminating, and decontaminating aqueous solutions. Previous experiments have shown that these solutions may be useful for firefighting purposes. This article describes experiments confirming the potential of using disinfecting, degassing, and decontaminating aqueous solutions as fire extinguishing agents. Fire tests were conducted to determine the fire extinguishing properties of an aqueous sulfonol solution using a Class A fire as an example. A method for assessing the electrical conductivity of a sulfonol solution to determine the critical micelle concentration is presented. The results of an experimenton producing fire-extinguishing foam filled with exhaust gases from an internal combustion engine are presented. The fire-extinguishing effect of this foam is compared to standard (air-filled) foam.

Design of fluorine-free foam extinguishing agent with high surface activity, foam stability and pool fire suppression by optimization of surfactant composition and foam system

The purpose of the study is offshore oil terminals, which are objects of increased fire danger in terms of fire safety. In this regard, the main requirements of fire safety include the implementation of a set of measures to create modern and efficient systems of port fire extinguishing of offshore oil terminals. The article investigates and analyzes the technological features of the modern complex of a block-modular system of foam fire extinguishing and water cooling of offshore berthing complexes of oil terminals. Unlike the traditional ones, the feature of the foaming agent of the intended purpose is the high efficiency of foams of low multiplicities based on the foaming agent of the intended purpose of the AFFF model. The content of a mixture of hydrocarbon and fluorocarbon film-forming surfactants ensures its effective use in fresh and marine aquatic environments.The use of a complex block-modular system of foam fire extinguishing and water cooling of offshore oil terminals allows you to implement a wide range of operations for extinguishing fires with effective isolation of combustible substances from oxidants and cooling of combustion centers of objects with a significant reduction in water consumption gorenje