Extinguishing Powder Research Articles

Preparation and characterization of NaAl(OH)2CO3 dry powder extinguishing agent with environmentally friendly and extinguishing efficiency

Preparation and characterization of NaAl(OH)2CO3 dry powder extinguishing agent with environmentally friendly and extinguishing efficiency

Modification and Application Performance Study of Ultra-Fine Dry Powder Extinguishing Agent.

Ultra-fine dry powder extinguishing agent (UDPEA) is a promising alternative to Halon agents in aviation firefighting. The formulation of UDPEAs should balance environmental friendliness and practical engineering requirements, including high extinguishing efficiency, excellent flowability, and prolonged anti-reignition. This study investigates the effects of three modification methods (single perfluorooctyl triethoxysilane (FOTS), single N-(3-Triethoxysilylpropyl)perfluoro(2,5-dimethyl-3,6-dioxanonanoyl)amide (PFPE), and a combination of FOTS and PFPE at various mass ratios (2.0:0.4, 1.6:0.8, 1.2:1.2, 0.8:1.6, 0.4:2.0) (g)) on the performance of sodium bicarbonate-based UDPEA. The results indicate that using FOTS or PFPE alone improves the water and oil contact angles, but still fails to meet the required hydrophobicity and oleophobicity standards, and it also reduces the flowability and fire-extinguishing capability. A combination of FOTS and PFPE at the 1:2 ratio yields the best performance, with the water and oil contact angles of 145.169° and 143.542°, respectively, the lowest flowability index (0.224), minimal extinguishing concentration and time (14.183 g/m3 and 1.976 s, respectively), which is only 52.7% and 68.3% of those of the unmodified UDPEA's (26.927 g/m3 and 2.893 s), and the longest anti-reignition time (68.5 s). In addition, the fire-extinguishing mechanisms (chemical inhibition and physical heat absorption) and anti-reignition mechanisms of the modified UDPEA (with the FOTS to PFPE ratio of 1:2) were revealed. This research aims to design an eco-friendly, high-performance UDPEA as an effective substitute for Halon extinguishing agents. These findings can provide valuable insights for evaluating and selecting aviation fire-extinguishing agents.

Experimental study on the inhibition of hydrogen deflagration by flame-retardant compounded ultrafine dry powder fire extinguishing media containing zinc hydroxystannate

With the rapid development of global hydrogen energy industry, the issue of hydrogen energy safety has emerged, it is prone to cause a serious explosion accident once hydrogen leaks. Therefore, it is urgent to develop efficient suppression media to reduce the severity of hydrogen explosion accidents. In this paper, a new compounded powder composed of ordinary ultra-fine dry powder extinguishing agent (ODPEA) and zinc hydroxystannate (ZHS) is prepared. On the basis of material preparation, an experimental system of hydrogen explosive suppression is established to explore the inhibitory effect of ODPEA-ZHS. In terms of explosion overpressure, the results show that the peak overpressure suppression rates of ODPEA-ZHS are 90.12 %, 92.31 %, and 93.04 % for hydrogen release pressures of 2.0, 4.0, and 6.0 MPa, respectively. Besides, the flame front propagation velocity under the action of ODPEA-ZHS reaches a suppression rate of 40.55 %. Furthermore, the overpressure suppression efficiency of ODPEA-ZHS exceeds 90 % when ignites 1.0 m axially from leak port. Ultimately, the physicochemical synergistic inhibition mechanism of ODPEA-ZHS is revealed by combining material characterization and pyrolysis results. This study can provide effective countermeasures for accident prevention in hydrogen energy industry, and also contribute to the establishment of hydrogen energy safety standards and norms.

КОМПЛЕКСНЫЙ ПОДХОД В ИССЛЕДОВАНИИ ОГНЕТУШАЩИХ ПОРОШКОВЫХ СРЕДСТВ ПРИ ЭКСПЕРТИЗЕ ПОЖАРОВ

The article discusses the possibility of using a set of instrumental methods, such as morphological analysis, elemental analysis, X-ray phase analysis, infrared spectroscopy, ion chromatography or capillary electrophoresis to study the chemical composition of fire extinguishing powders during fire-technical examinations. Examples of the use of these methods in the investigation of real fires are given. It is described in detail how studies of fire extinguishing agents are carried out to answer questions related to establishing their composition, as well as identifying the compliance of the fire extinguishing powder submitted for study with technical documentation. It is shown that in order to obtain complete information about the chemical composition of the fire extinguishing agent, it is necessary to use a set of methods, since each of the considered methods provides additional information during the study.

Preparation of NaHCO3 fire extinguishing agent with perfluoropolyether groups to inhibit rapid re-ignition of Class B fires

To enhance the fire suppression effectiveness of dry powder extinguishing agents against Class B fires, the environmentally friendly surface modification of dry powder fire extinguishing agents using long-chain perfluoropolyether silanes (LCPS) was designed to modify the extinguishant. LCPS was synthesized by combining perfluoropolyether methyl ester (PME, Mw=4000 g/mol) and N-(β-aminoethyl)-γ-aminopropyltriethoxysilane (AAPS). A novel hydrophobic and oleophobic ultrafine dry powder fire extinguishing agent (LCPS-Na) was obtained by the introduction of LCPS into tetraethyl orthosilicate (TEOS)-modified ultrafine NaHCO3 powder (Na-UDP). The contact angles of water (WCA) and oil (OCA) on LCPS-Na are 151.4° and 145.8°, respectively. The hydrophobicity and oleophobicity of LCPS-Na are determined to be 94.2% and 85.6%, respectively. Moreover, the required concentrations of LCPS-Na powder to extinguish n-heptane and aviation kerosene fires are found to be 38.3 g/m3 and 39.7 g/m3, respectively, with a reduction of 31.6% and 31.0% compared to that of Na-UDP. The rekindling time for aviation kerosene after fire suppression was significantly prolonged to 40.6 s compared to Na-UDP (0.20 s), owing to the superior floating capability of LCPS-Na.

Synthesis of magnesium hydroxide powder and dry powders for application in extinguishing petroleum fires

AbstractFire extinguishing agents are an important factor in the fight against fires. In this study, a new composite powder (CSPMS) was synthesized and used to extinguish fires caused by petroleum products. SiO2 nanoparticles, Mg(OH)2 nanoparticles, and nanocomposites of NH4H2PO4/chitosan (CSP) were combined to generate CSPMS powder. The structure and morphology of the material were characterized using methods such as XRD, SEM, FTIR, etc. The results showed that the synthesized Mg(OH)2 nanoparticle size ranged from 20 to 30 nm, and the NH4H2PO4 nanoparticle size ranged from 800 to 900 nm on the chitosan surface. The CSPMS material had particle sizes ranging from 2 to 3 µm, with a uniform distribution of SiO2 nanoparticles (50–100 nm) and Mg(OH)2 nanoparticles on the surface. The powdered materials were applied to extinguish gasoline and oil fires. CSPMS sample demonstrated the best fire extinguishing time and powder consumption (5.8 s and 12.2 g, respectively) and CO emission below the threshold of 400 ppm. Small‐scale fire extinguishing tests showed that CSPMS powder had better fire extinguishing capability, cooling time, and CO gas adsorption ability compared to commercial fire extinguishing powder.

УЧЕТ ЭФФЕКТИВНОСТИ ОГНЕТУШАЩИХ ВЕЩЕСТВ ПРИ ОСНАЩЕНИИ ПЕРЕНОСНЫМИ ПОРОШКОВЫМИ ОГНЕТУШИТЕЛЯМИ

In the article, the normative extinguishing capacity of substances is compared with the results of experiments on extinguishing class B fires. It is shown that the normative, real and laboratory effectiveness of powder extinguishing compositions are in good agreement.
 The presented studies confirm that the effectiveness of class B flame suppression can be improved by a factor of two by adding a small amount of inhibitor to the inert substance. The issue of equipping the object of protection with powder fire extinguishers is discussed from the point of view of taking into account their effectiveness. It is shown that due to the low requirements for the quantity and quality of fire extinguishers, a fire safety specialist must carefully pay attention to the weight, installation location and actual effectiveness of the fire extinguisher to improve the quality of the fire prevention system at the protection facility.

Numerical Study of the Effect of Primary Nozzle Geometry on Supersonic Gas-Solid Jet of Bypass Injected Dry Powder Fire Extinguishing Device

A two-way coupled model between polydisperse particle phases with compressible gases and a density-based coupling implicit solution method, combining the third-order MUSCL with QUICK spatial discretization scheme and the second-order temporal discretization scheme, are constructed based on the discrete-phase model (DPM) and the stochastic wander model (DRWM) in the Eulerian–Lagrangian framework in conjunction with a unitary particulate source (PSIC) approach and the SST k-ω turbulence model. The accuracy of the numerical prediction method is verified using previous supersonic nozzle gas-solid two-phase flow experiments. Numerical simulation of a two-phase jet of dry powder extinguishing agent gas with pilot-type supersonic nozzle was performed to analyze the influence of geometrical parameters, such as the length ratio rL and the area ratio rA of the main nozzle on the two-phase flow field, as well as on the jet performance indexes, such as the particle mean velocity vp,a, velocity inhomogeneity Φvp, particle dispersion Ψp, particle mean acceleration ap,a, etc. By analyzing the parameters, we indicate the requirements for the combination of jet performance metrics for different flame types such as penetrating, spreading, and dispersing.

The effectiveness of mechanisms of heterogeneous and homogeneous inhibition of flame particles taking by extinguishing powder particles, into account the rate of their formation

The relevance of the work is due to the need to improve the technology of extinguishing fire with extinguishing powders based on the study of the laws of the physicochemical processes of interrupting chain combustion reactions, in particular, heterogeneous and homogeneous mechanisms of inhibition of active flame centers by powder particles. The aim of the work is to evaluate the effectiveness of non-stationary mechanisms of heterogeneous and homogeneous inhibition of active flame particles by fire extinguishing powder particles taking into account the rate of their birth, as well as to compare the contributions of each of the mechanisms to the result of fire extinguishing. Mathematical modeling of the mechanisms of heterogeneous and homogeneous inhibition of active flame particles by fire extinguishing powder particles is carried out, taking into account the rate of birth of active particles of in flame. The theoretical dependences of the rates of reactions of heterogeneous and homogeneous inhibition of active flame particles on the dispersed characteristics of powder particles, their residence time in the zone of flame and the characteristic durations of inhibition reactions are obtained. It is established that the condition for the effective recovery inhibition of active particles of flame by the mechanisms under consideration is exceeding the time of interaction of powder particles with active flame particles over the duration of inhibition processes, as well as an excess of the rate of inhibition of active flame particles over the rate of their birth. The rate of inhibition of active particles of flame depends on the particle size of the extinguishing powder, namely, the smaller the particle size of the powder, the greater the rate of inhibition. This dependence is observed explicitly for the mechanism of heterogeneous inhibition of active particles of flame and implicitly for the mechanism of homogeneous inhibition through the dependence of the rate of thermal production of metal oxide radicals of the extinguishing powder involved in this process on the size of the powder particles. The presence of two stages in the implementation of the mechanism of homogeneous inhibition of active flame particles (thermal production of metal oxide radicals of the powder substances used and the inhibition process itself) allows us to consider this mechanism of extraction of active particles longer than the mechanism of heterogeneous reduction, and, therefore, it does not significantly contribute to the chemical process of extinguishing a fire.

Correction: High-Temperature Oxidation and Hot Corrosion Behaviors and Mechanism of One Typical Aero-Engine Material 0Cr18Ni9 by One Novel Superhydrophobic and Oleophobic Ultrafine Dry Powder Extinguishing Agent

Correction: High-Temperature Oxidation and Hot Corrosion Behaviors and Mechanism of One Typical Aero-Engine Material 0Cr18Ni9 by One Novel Superhydrophobic and Oleophobic Ultrafine Dry Powder Extinguishing Agent

Влияние кристаллогидратов солей в огнетушащем порошковом составе на его удельную эффективность тушения легковоспламеняющейся жидкости

The article presents the comparative evaluation of specific fire extinguishing efficiency of powder compositions containing crystalline hydrate salts as a gas-generating component. Thermodynamic calculations and experimental tests have shown a reduction in the consumption of powder compositions for extinguishing highly flammable liquids by at least 30% when hexahydrate of magnesium-ammonium phosphate MgNH4PO4∙6H2O is used as a component of fire extinguishing powders. The research has shown the advantage of implementing fine particles of crystalline hydrates (d<10 μm) obtained during the controlled precipitation process compared to analogs manufactured by mechanical grinding (d < 100 μm).

High-Temperature Oxidation and Hot Corrosion Behaviors and Mechanism of One Typical Aero-Engine Material 0Cr18Ni9 by One Novel Superhydrophobic and Oleophobic Ultrafine Dry Powder Extinguishing Agent

High-Temperature Oxidation and Hot Corrosion Behaviors and Mechanism of One Typical Aero-Engine Material 0Cr18Ni9 by One Novel Superhydrophobic and Oleophobic Ultrafine Dry Powder Extinguishing Agent

A novel approach for enhancing fire suppression efficiency of dry powder extinguishant: From the synergistic effect of dawsonite

A novel superfine dry powder extinguishing agent (DW-SDE) was developed by combining dawsonite (NaAl(OH)2CO3, DW) with superfine ABC dry powder fire extinguishing agent (SDE). The micro-morphology of DW transforms into a near-spherical shape (D90 = 8.33 μm) under optimal conditions including a mass ratio of 1:10 for citric acid (ZS) to aluminum hydroxide, a reaction time of 8 h, and a reaction temperature of 150 °C. The D90 of DW-SDE is 11.20 μm which is less than that of SDE (D90 = 14.46 μm). The activation energy (E) of DW-SDE is lower (E = 102.0 kJ/mol) and the thermal decomposition of DW-SDE can absorb more heat (388.7 J/mg). Moreover, the flowability of DW-SDE is superior to that of SDE and commercial ABC dry powder extinguishing agent (CDE). Furthermore, the DW-SDE can completely extinguish a fire in 8.7 s at 0.6 MPa, which is 47.4% and 27.1% faster than that of CDE and SDE.

Analysis of combustion characteristics of wood stack and absolute ethanol in fire extinguishing experiment

For the purpose of researching the rules of combustion heat release, ammonium phosphate dry powder extinguishing agent and water-based fire extinguishing agent were utilized before and after the class A fire common wood stack ignition fuel and class B fire anhydrous ethanol ignition fuel fire extinguishing. For wood stack fire, 0.5A wood stack was used for blank combustion test, and the pan fire ignition method for the same type and scale of wood stack fire extinguishing experiment. For absolute ethanol fire, fire suppression was studied using a 13B scale. The change characteristics of the combustion field before and after action of the dry powder extinguishing agent and water system extinguishing agent were measured by thermocouple, heat flow meter and digital camera. The findings of the experiment demonstrated that in the combustion experiment of wood stack, the temperature of 0.5A wood stack of the blank group could reach 800 °C, and the temperature reduction rate of free combustion was 2.62 °C/s. It took an average of 36.5s and 2.25 kg of ammonium phosphate dry powder to put out the fire，and the temperature reduction rate was 4.18 °C/s. The average amount of water-based extinguishing agent used to extinguish a fire was 1.21 kg, yet the average time to do so was just 12.5 s, and the average rate of temperature drop was 10.14 °C/s. In the experiment where an ethanol pool fire was being burned, the typical amount of water-based fire extinguishing chemical used was 3.44 kg, and the typical extinguishing time was 18 s, the maximum temperature drop rate could reach 35.6 °C/s in the initial stage of fire extinguishing, despite the fact that the dry powder fire extinguisher containing ammonium phosphate was used, the fire was not properly controlled.

In Ukrainian

Efficient and environmentally friendly means for fire extinguishing can reduce extreme economic losses from fires and protect people's lives and property. A separate problem is extinguishing oil products on the water surface. Dry water is a new type of environmentally friendly fire extinguishing agent. It is a powder with a water content of more than 90 %, so it has excellent fire extinguishing properties. The purpose of this work was to obtain dry water fire extinguishing powders based on pyrogenic hydrophobic methyl silica with bentonite and to study their fire extinguishing properties in case of extinguishing gasoline on water surface. To obtain dry water fire extinguishing powders, there were used distilled water, Dashukovsky bentonite (Ukraine), and pyrogenic methyl silica (AM-300 brand, Ssp = 300 m2/g, particle size 5–7 nm) (Kalush, Ukraine). Dry water fire extinguishing powder was prepared by mixing the components at a speed of 15000 rpm for 10 s. Were made samples containing 10 wt. % methyl silica, 3, 6, 10, and 15 wt. % bentonite and the corresponding amount of water. The bulk density was 0.423, 0.453, 0.459, and 0.464 g/cm3 for samples of 3, 6, 10, and 15 wt. % bentonite, respectively. Optical microscopy has shown that the particles of the dry water powder have a clearly visible core-shell structure. Dry water fire extinguishing powder is a polydisperse system - most of the particles are single fine particles with a size of 1 micron or less, and there are also agglomerates with a size of more than 5 microns. As a result of the mechanical destruction of individual bentonite particles during high-speed mixing of components, bentonite particles are destroyed, therefore, individual bentonite particles are surrounded by a hydrophobic-hydrophilic mixture of hydrophobic silica nanoparticles and bentonite nanoparticles formed during exfoliation. The study of the fire-extinguishing properties of the dry water powder was carried out by spraying it onto a layer of burning gasoline A92 on water surface. The time to complete extinguishing of the fire and the consumption of the substance per unit area of burning were determined. It has been determined that the time for extinguishing gasoline and the consumption of dry water fire extinguishing powder for extinguishing it depend on the concentration of bentonite and are for 3, 6, 10, and 15 wt. % 9, 7, 6, and 9 s and 0.333, 0.309, 0.284, and 0.260 g/cm3, respectively. The developed dry water fire extinguishing powders are environmentally friendly, have good fire extinguishing properties, and can be used to extinguish oil products on the surface of water bodies.

JUSTIFICATION OF THE TECHNOLOGY OF FIRE EXTINGUISHING MATERIALS BASED ON AMMONIUM PHOSPHATE

In this paper, the justification of the technology of fire extinguishing materials based on ammonium phosphate is carried out, a justification for the production of fire extinguishing powder using MOSS technology with incoherent grinding of impurities has been developed and, accordingly, a block diagram is given. A technological scheme for the production of fire extinguishing powder materials crushed using the technology of isolated base mixtures has been developed, and information is provided on the technological calculations used in the scheme of basic and auxiliary means, as well as on the required material balance of 1 ton of fire suppressing powder according to this technology.

Justification of the technology of fire extinguishing materials based on ammonium phosphate

In this paper, the justification of the technology of fire extinguishing materials based on ammonium phosphate is carried out, a justification for the production of fire extinguishing powder using MOSS technology with incoherent grinding of impurities has been developed and, accordingly, a block diagram is given. A technological scheme for the production of fire extinguishing powder materials crushed using the technology of isolated base mixtures has been developed, and information is provided on the technological calculations used in the scheme of basic and auxiliary means, as well as on the required material balance of 1 ton of fire suppressing powder according to this technology.

Study on Modification Technology of Superfine Dry Powder Fire Extinguishing Agent

The superfine dry powder fire extinguishing agent has the characteristics of high fire extinguishing efficiency and low cost and has been widely used in the field of fire extinguishing. This paper briefly describes the classification and current problems of dry powder and analyzes the current technology of micronization and surface modification. The superfine dry powder fire extinguishing agent is greatly improved in water resistance by surface grafting modification, the water repellency meets the standard requirements, and the D90 particle size of the dry powder extinguishing agent after modification is ≤15μm.

Alkaline potassium aluminum carbonate: A novel high-efficiency dry powder extinguishing agent with high heat-resistant

Alkaline potassium aluminum carbonate (KAl(OH)2CO3) has potential application as an active medium for dry powder fire extinguishing due to its special molecular structure. In this paper, the application of KAl(OH)2CO3 as a high-temperature resistant dry powder extinguishing agent is first discussed. Firstly, the pyrolysis kinetics of KAl(OH)2CO3 was explored using thermal analysis techniques, including model-free and model-fitting methods. The pyrolysis of KAl(OH)2CO3 can be divided into three stages, with E values of 357.7 and 244.8 kJ/mol for stage 1 and stage 3, respectively. Higher activation energy of KAl(OH)2CO3 (T5 wt%=550 K, Tmax=648 K) means that it will not be deactivated prematurely in the high-temperature region. Moreover, the fire-extinguishing performance of KAl(OH)2CO3 is much better than that of BC dry powder fire extinguishing agent, which can suppress n-heptane and aviation kerosene pool fires within 6.00 s and 7.21 s. The possible fire-extinguishing mechanism of KAl(OH)2CO3 is also proposed. Therefore, KAl(OH)2CO3 is expected to be a high-temperature resistant dry powder extinguishing agent, which solves the application of existing dry powder fire extinguishing agents in high-temperature areas such as aircraft engine compartments.

Analysis of the chosen thermal and flammability parameters of dried sewage dust

The hazardous sludge disposal process in the form of landfills requires the determination inter alia of the flammable and explosion properties of dried sewage sludge dust, which has the ability to ignite and spontaneously combust when stored in silos. At a constant furnace surface temperature, the minimum ignition temperature of the sludge dust layer with a layer thickness of 5 mm is 270 °C, and for a layer thickness of 12.5 mm it is 250 °C. Two selected fire extinguishing powders for Class A, B, C and D fires were used in the study to determine the possibility of reducing the susceptibility of dried wastewater to ignition from heated surface, self-ignition and explosion parameters. The most effective extinguishing powder was ABC Favorit, which increased the value of the minimum ignition temperature of the layer (5 mm thick) to 360 °C and the spontaneous ignition temperature of the sludge with this powder increased by 22 °C at 169.6 cm3 in comparison to the sludge without extinguishing powder, respectively. The lowest self-ignition temperature of 136 °C was recorded for the largest tested volume (169.6 cm3) for dried sewage dust without any fire extinguishing powders. The biggest values of pmax and (dp/dt)max dried sewage dust were recorded 4.8 bar and 113 bar/s respectively. By analysing the obtained test results, it can be assumed that dried sewage dust is a combustible material with properties similar to biomass.