Mist Suppression Research Articles

Impact of the novel chlorinated polyfluorinated ether sulfonate, F-53B, on gill structure and reproductive toxicity in zebrafish

6:2 Chlorinated polyfluorinated ether sulfonate, commonly known as F-53B, is widely used as a mist suppressant in various industries and is frequently detected in the environment. Despite its prevalent presence, the adverse effects of F-53B are not well understood and require future investigation. This study utilized zebrafish embryos and adults to examine the toxic effects of F-53B. Our findings revealed that F-53B impaired gill structure and increased erythrocyte numbers in adult zebrafish. Notably, F-53B demonstrated a higher sensitivity for inducing mortality (LC50 at 96 h) in adult zebrafish compared to embryos. Additionally, F-53B disrupted the expression of critical steroidogenic genes and hindered sex hormone production, which negatively affecting egg production. In conclusion, this study underscores the detrimental impact of F-53B on gill structure and reproductive toxicity in zebrafish, providing valuable insights into its overall toxicity.

Fire prevention and mitigation technologies in high-rise buildings: A bibliometric analysis from 2010 to 2023

PurposeThis study provides a comprehensive bibliometric analysis for research in the area of fire prevention and mitigation in high-rise buildings, an emerging crucial subject. The analysis covers the period between 2010 and 2023, with the main goal of classifying and evaluating the efficacy of fire prevention and mitigation technologies. MethodsThe current study contributes a methodological approach for analyzing fire safety measures and highlighting the critical necessity for multidisciplinary approaches in enhancing fire safety protocols, with a special focus on the integration of advanced fire detection, suppression, and evacuation technologies. The investigation indicates a steady 10 % growth rate in scholarly production on this topic. ResultsResearch on active fire prevention technologies has focused on the technologies including; 1) water mist suppression, 2) unmanned aerial vehicles, 3) Artificial Intelligence (AI) algorithms, and 4) Internet of Things (IoT) frameworks, while research on passive technologies has trended toward fire compartmentation and fire-resistant materials. The study identifies 6 passive technologies and 14 active technologies, with active technologies focusing on water mist suppression, AI algorithms, and IoT frameworks. On the other hand, passive technologies focus on risk assessment, fire protection, and management. ConclusionsThe current study analyzes the role of risk assessment, fire protection, and management in the development of the field of fire mitigation and prevention. The study highlights research collaboration toward reducing risk and fatalities by fire prevention and mitigation solutions. The US and China have the highest collaboration in these technologies, while the UK and the US have the highest publications. Research implicationsThe provided analysis ultimately serves as guidance for stakeholders involved in the design, policy-making, and implementation of fire safety measures in urban high-rise environments, and can give insight on future research direction toward effective strategies and technologies for fire mitigation and prevention in high-rise buildings.

Joint OH-PLIF and Mie scattering imaging of enhanced water mist suppression of buoyant fires

This study presents the first near-field measurements of interactions between reaction layers and water mist droplets suppressing a buoyant turbulent diffusion flame that is representative of a fire. Joint Mie scattering and OH-PLIF are employed at a high repetition rate of 400 Hz to image the droplet field and OH structure, which are deemed here to approximate the high-temperature reaction zone. Compressed natural gas (CNG) buoyant diffusion flames are stabilised on the Sydney Turbulent Buoyant Fire Burner, which is surrounded by a low-velocity air co-flow that is seeded with fine water mist droplets (d32 ∼ 50 µm). The water mist is doped with varying concentrations of metal alkali salts (NaHCO3, KHCO3) that release radical scavenging molecules, providing enhanced suppression capabilities through chemical inhibition in addition to the quenching effect from the water droplets. The spray boundary condition across the wind tunnel exit plane is quantified using Phase Doppler Interferometry. Flame extinction limits are measured by defining the critical condition at which the flame destabilises and lifts off the burner exit plane. A stability map is developed to quantify suppression efficacy in terms of the water mist flow rate and inhibitor concentration. Joint Mie-OH images of selected cases at varying extinction levels show that the addition of inhibitor introduces frequent breakages in the OH layers, marking regions of local extinction and reignition. Large mass fractions of inhibitor in the water, which, once evaporated, produces excess salt crystals in the local extinction zones that causes streaks of salt clouds that line both the lean and rich side of the flame. The chemical scavenging effects of the OH radical by NaHCO3 and KHCO3 is quantified by evaluating the reduction of the mean OH fluorescence signal in the flame at varying locations. Probability density functions for the OH area characterise local extinction in the flame due to the radical scavengers. The order of OH radical depletion and localised extinction in the flame due to the water mist follows: KHCO3 > NaHCO3 > H2O.

Effective Adsorption of Chlorinated Polyfluoroalkyl Ether Sulfonates from Wastewater by Nano-Activated Carbon: Performance and Mechanisms

Chlorinated polyfluoroalkyl ether sulfonates (F-53B) were often used as mist suppressants in the chrome plating industry, resulting in the large discharge of F-53B-containing electroplating wastewater into the aquatic environment. Due to the high toxicity of F-53B, increasing attention has been paid to its efficient removal from wastewater. In this study, three nano-activated carbons were successfully prepared from coconut shell carbons by a simple one-step KOH activation method. The nitrogen adsorption/desorption experiments showed that the synthesized coconut shell activated carbons possessed a well-developed nano-pore structure, which was favorable for the adsorption of F-53B. The results suggested that the adsorption of F-53B on the coconut shell activated carbons followed pseudo-second-order kinetics and was better fitted in the Langmuir isotherm, indicating that the adsorption of F-53B was mainly controlled by chemical adsorption and was mainly monolayer adsorption. Theoretical calculation results revealed that the faster adsorption rate of F-53B on CSAC_800 than on CSAC_600 and CSAC_700 could be contributed to the lower adsorption energy of F-53B on CSAC_800 and the higher self-diffusion coefficients of F-53B in CSAC_800. The higher adsorption capacity of CSAC_800 (qm = 537.6 mg·g−1) for F-53B than that of CSAC_600 (qm = 396.83 mg·g−1) and CSAC_700 (qm = 476.19 mg·g−1) could be attributed to the higher specific surface area and larger number of adsorption sites of CSAC_800. The results of this study demonstrate that coconut shell activated carbons with a well-developed nano-pore structure are an effective adsorbent for F-53B removal and have a good application prospect.

HBM4EU chromates study – PFAS exposure in electroplaters and bystanders

The study aims to reveal the exposure to perfluoroalkyl substances (PFAS) in workers in different industry sectors with exposures to hexavalent chromium (Cr(VI)). The PFAS exposure of in total 172 individuals from 4 countries was assessed by the determination of 8 perfluoroalkyl carboxylic acids and 4 perfluoroalkyl sulfonic acids in plasma samples. The participants were 52 chrome plating workers, 43 welders, 3 surface treating workers and 74 workers without any occupational Cr exposure as controls. Significant differences between workers with Cr exposure and controls were found for the perfluoroalkyl sulfonic acids, particularly for perfluorooctane sulfonic acid (PFOS). The median and maximum levels were, respectively, 4.83 and 789 μg/l for chrome plating workers, 4.97 and 1513 μg/l for welders, and 3.65 and 13.9 μg/l for controls. The considerably high PFOS exposure in Cr platers and welders can be explained by the former application of PFOS as mist suppressants in electroplating baths, which resulted in an exposure of the directly involved operators, but also of welders performing maintenance and repair service at these workplaces.

Numerical Simulation on Methane Coal Dust Composite Explosion in Restricted Space by Ultrafine Water Mist Suppression

The purpose of this experimental investigation was to examine the effects of ultrafine water mist on explosions caused by methane and coal dust hybrids that occurred inside of a closed vessel. In this study, we built a small-scale semi-closed visualization experimental platform and ran simulations to study the effects of four factors on the explosion of methane coal mixtures: the amount of ultra-fine water mist sprayed, the volume fraction of methane, the position of the methane inlet, and the amount of time it took to premix. This allowed us to gain a deeper understanding of the repressive effect of this water mist on methane explosion. The findings demonstrate that ultrafine water mist is capable of suppressing methane explosions, with a notable inhibitory effect on 10% methane. This inhibitory effect becomes stronger with increasing amounts of sprayed ultrafine water mist. The effect of methane volume fraction on the maximum explosion overpressure Δ

ANALYSIS OF HEAT RELEASE RATE IN ENGINE ROOM FIRES OF 300 GT FERRY RO-RO PASSENGER BY USING WATER MIST SYSTEM AND CO2 SYSTEM

Based on statistical data in recent years, there are still quite a number of ship accidents due to fires, including on passenger ships. The water mist system is a fire suppression system that allows it to be used in the engine room with the advantage that it can keep the heat production rate low during the extinguishing process and can be operated earlier than the CO2 system. The research is conducted by using fire dynamic simulator in the engine room of a 300 GT ferry ro-ro passenger to compare the heat release rate of fire without an extinguishing system, an existing CO2 system, and a water mist system. The result shows that the CO2 fire suppression system reduces the heat release rate more rapidly to the decay phase at 375 seconds while the water mist takes more than 900 seconds. However, the fully developed phase of the water mist suppression system occurs more quickly than CO2 because the sprinklers are activated shortly after a fire occurs. Unlike water mist, the CO2 system is activated at 60 seconds so that the pre-combustion, growth, flashover, and fully developed phases are at the same HRR and time as the natural one.

Water Mist Fire Suppression Systems for Building and Industrial Applications: Issues and Challenges

Interest in water mist fire suppression has increased within the fire protection industry due to its ability to control the spread and development of fire without using environmentally damaging agents. Water mist fire suppression has been used for many years in various applications such as machinery spaces, combustion turbine enclosures, and onboard passenger sea vessels. Now there is a demand to use this firefighting method to protect other fire risks such as cooking areas, commercial buildings, residential buildings, electrical equipment, road tunnels, bushfire (wildland fire) protection, and nuclear power generation facilities. To support this industry demand, this review covers the fundamentals of water mist, its suppression mechanisms, areas of application, existing research and development, and the codes and standards related to design. This comprehensive review provides a clear history of water mist suppression. It is able to identify the issues and challenges related to the technology to help pave the way for future research and development that will improve these systems to a level so that they are suitable for these new applications and meet the industry demand for nontoxic fire suppression systems.

The investigation of the water mist suppression pool fire process's flame expansion characteristics

Flame expansion is a typical fire suppression phenomenon that happens during the water mist suppression of liquid fuel fires, particularly heavy oil fires, and poses a risk to process safety. A series of transformer oil fire expansion experiments were carried out to study the mechanism of flame expansion in the process of water mist suppression pool fires. A theoretical model of the interaction of water mist with flame and hot fuel was developed after a quantitative investigation of flame structure changes during expansion. According to the results of the study, the presence of a fuel-rich vapor layer on the oil pool's surface is a prerequisite for flame intensification, and the thickness of this layer is proportional to the height of the transformer oil flame, Lc=0.195Lf. Furthermore, the impact of water mist on the fuel-rich vapor layer is found to be the principal cause of flame expansion, and the transformer oil flame expansion rate is determined using a combination of theoretical and experimental methods, φv=13.9−41.8. Finally, one of the factors that aggravates flame expansion is the overpressure on the fuel surface caused by the water-oil mixture. Droplet size reduces as water mist pressure rises, and flame expansion shifts from the parallel effect of jet impact and water-oil mixing to the serial effect, lowering the flame expansion rate. As a result, reducing droplet size causes flame expansion to weaken.

6:2 Chlorinated polyfluoroalkyl ether sulfonate as perfluorooctanesulfonate alternative in the electroplating industry and the receiving environment.

Electroplating industry is an important application field of per- and polyfluoroalkyl substances (PFASs) as the chromium mist suppressants. 6:2 chlorinated polyfluoroalkyl ether sulfonate (6:2 Cl-PFAES) and perfluorooctanesulfonate (PFOS) have been the two widely used mist suppressants, and after the ban of PFOS, 6:2 Cl-PFAES will become the dominant suppressant. The behavior and mechanisms of 6:2 Cl-PFAES in the electroplating industry and the receiving environment were studied and compared with PFOS. 6:2 Cl-PFAES behaved similarly with PFOS due to their similar chemical structure. However, some difference exists for the relatively stronger hydrophobicity of 6:2 Cl-PFAES. Up to 35.7mg/L of PFOS and 13.4mg/L of 6:2 Cl-PFAES were found in the industrial wastewater influents, and were effectively reduced to 0.3-0.8mg/L by the interaction with chromium hydroxide through hydrophobic interaction and ligand exchange. The stronger hydrophobicity of 6:2 Cl-PFAES than PFOS resulted in its accumulation in the surface of foams and comparable or less removal during the industrial and municipal wastewater treatment. 6:2 Cl-PFAES exhibited higher bioaccumulation potential than PFOS in the surface water. 6:2 Cl-PFAES emitted by both mists and water may pose health risks to humans. More attentions towards 6:2 Cl-PFAES are needed after the replacement of PFOS by it in the electroplating industry as a global contaminant of emerging concerns.

Influence of Water Mist Temperature Approach on Fire Extinguishing Effect of Different Pool Fires

The aim of this paper was to study the suppression influence of water mist on oil pool fires, taking diesel fires and n-heptane fires as experimental objects. The effects of spray pressure and temperature on water mist suppression were examined, and an experimental platform for the suppression of water mist in a small space was set up. Their fire prevention performance and fire extinguishing mechanisms were analyzed by comparing the flame temperature and extinguishing time of diesel and n-heptane pool fire. Three types of spray pressure were set. Water mist was designed at different temperatures and design experiments were carried out for this purpose. The change process of smoke concentration, thermocouple temperature, and flame combustion under different working conditions were analyzed, and the factors affecting the fire extinguishing effect of water mist on oil pool fire were discussed. The results show that 20 °C water mist is more effective at medium and high pressure than at low pressure. Moreover, 80 °C water mist at 9 MPa is more effective in extinguishing n-heptane fire. The flame extinction time is about 10 s, which is more than 40 s higher than that of cold water.

Human exposure to F-53B in China and the evaluation of its potential toxicity: An overview.

Chlorinated polyfluoroalkyl ether sulfonic acid (Cl-PFESAs, trade name F-53B), an alternative to perfluorooctane sulfonate (PFOS), has been widely used as a mist suppressant in the Chinese electroplating industry since the 1970s. Due to greater restrictions on PFOS globally in recent years, the production and use of F-53B correspondingly increased, consequently causing more emissions into the environment. In China, an increasing number of studies report frequent detection and broad exposure to F-53B in the natural environment, various wildlife and the human body. In human blood, the detection rate of F-53B is almost 80%, accounting for 8.69 to 28% of ∑per- and polyfluoroalkyl substances (PFASs). F-53B is the most biopersistent PFAS in humans to date, with a half-life of 15.3years. In addition, F-53B displays protein binding affinity and high human placental permeability. Recently, some epidemiological studies have reported the health risks associated with F-53B in humans, including abnormal serum lipid metabolism, vascular dysfunction, endocrine disorders and even adverse birth outcomes. Various in vivo and in vitro studies have demonstrated the toxicity of F-53B, such as hepatotoxicity, interference effects on the endocrine system, as well as reproductive and developmental toxicity. Our aims are to review studies on human F-53B exposure levels, trends and associated health effects; evaluate the potential toxicity; and predict directions for future research.

Stacking polymer microspheres matrix: a facile, practical, and energy-saving strategy for suppression of acid mist

ABSTRACT The electroplating, electrolysis, and pickling industrial processes would generate numerous gas pollutes, acid mist, which could not be essentially diminished due to its synthesis mechanism and cause gaseous environmental pollution, equipment corrosion, and endanger workers’ health. In this study, a facile, practical, and energy-saving acid mist suppression system was constructed by introducing a stacking microsphere matrix as a floating porous phase on the acid solution and not causing secondary pollution. The mechanism of this green acid mist suppression strategy mainly focused on size-selective blocking of acid mist droplets by dense stacking microsphere layer and dissipation of floating kinetic energy of bubbles in the acid mist. The factors relating to the matrix's microstructure, the particle size of microspheres, the combination of the complex particles with a wide range of particle sizes, and the thickness of the matrix on the acid mist suppression were explored. It found that the matrix constituted of a medium-sized polymer sphere (1.075 ± 0.175 mm) presents a better appearance in the acid mist suppression. When the thickness of this matrix reached 15 mm, its acid mist efficiency also came up to 100%, totally blocking the acid mist. Meanwhile, complex particles with different particle sizes and PMMA porous blocks are beneficial for suppressing acid mist. Herein, this research opened up a green and effective strategy for regulating this hazardous gas pollute, acid mist.

Energy distribution analysis on suppressing a shielded fire with water mist in a tunnel rescue station

In real tunnel fire scenarios, water mist has little opportunities to directly apply to train fires shielded by a carriage body. However, most models for heat transfer analysis assume direct contact between fire source and mist droplets. It is of interest to find a method to evaluate the energy exchange between water mist and a shielded fire. To investigate the water mist suppression performance on a shielded fire, a full-scale experimental and theoretical study was performed by varying the activation time of water mist system, working pressure, and the diameter of mist droplets. The suppression performance is found to be dependent on the working pressure for the small mist droplets, and sensitive to the size of mist droplets at high working pressure. Moreover, the suppression performance is also influenced by the water mist activation time due to the competition of fuel cooling and the inhibition effect of the smoke layer. A theoretical model was developed to predict the energy exchange among smoke, water mist, and surroundings. It was found that in comparison to the indirectly restricted effect of cooling the carriage and fire, the direct heat loss between water mist and smoke is the main controlling mechanism. This study provides an important reference for the design of fire water system in the tunnel rescue station and is beneficial to the environmental protection of fire extinguishing sites.

Developing potency factors for thyroid hormone disruption by PFASs using TTR-TRβ CALUX® bioassay and assessment of PFASs mixtures in technical products.

Over the last decade, per- and polyfluoroalkyl substances (PFASs) have become one of the most heavily investigated persistent organohalogen compound class of environmental concern. However, knowledge about their toxicology is still scarce, although PFASs as individual compounds and their industrial mixtures were shown to exert effects on the thyroid hormone system. In vitro toxicity potency factors were established for thyroid hormone transport disruption potential using the novel TTR-TRβ CALUX® bioassay for major PFASs. We assessed technical PFASs mixtures, including aqueous film-forming foam (AFFF) surfactants and chromium mist suppressants (CMS) applications with and without total oxidizable precursor (TOP) by TTR-TRβ CALUX® assay for their thyroid hormone transport disrupting potential. All PFASs listed in the German guideline for drinking water (German Environment Agency, 2017) affected the T4 binding to TTR, an important plasma thyroid hormone transport protein. For all tested PFASs, potency factors based on PC80 values relative to PFOA could be obtained and ranged between PFBA (0.0018) and PFOS (2.0). Applying in vitro potency factors obtained from the present in vitro TTR-TRβ CALUX® assay study and recently reported in vivo potency factors (Zeilmaker et al., 2018; Bil et al., 2021) on the above-mentioned German guideline for PFAS in drinking water, showed that the cumulative effect-based trigger values (in vivo and in vitro) are comparable (3.0 vs. 2.9 to 4.6μg PFOA-EQ/l). Additionally, AFFF surfactants and CMS with and without TOP assay were tested. Highest activities were found in the older AFFF surfactants (2013/2014) due to higher PFOS/PFOA levels, which were already substituted with 6:2 FTS in 2019, resulting in much lower PFOA-EQ levels. As expected also the PFOA-EQ levels increased in the samples with TOP treatment compared to the original AFFF surfactants and CMS as confirmed here by biological and chemical PFOA-equivalents (PFOA-EQ) analysis. Additionally, CMS (which have been used in the electroplating chromium industry since the 1950s) as well as PFOS-free, but not PFAS-free fume suppressants (such as Fumetrol® 21) have been tested in the TTR-TRβ CALUX® assay and showed much lower activity levels then the AFFFs, confirmed by the similar potency determination based on chemical PFASs analysis followed by transformation to PFOA-EQ for comparison. The potency factor of 6:2 FTS, which is the main substitute for PFOS in CMS, indicates that it is approximately 100-times less potent as a thyroid hormone disruptor as compared to PFOS. Potency factors based on PC80 values from TTR-TRβ CALUX® relative to PFOA have been developed for major PFASs. In AFFF surfactants and CMS a trend of higher activities with higher amounts of PFOS and PFOA have been found. PFOA and PFOS showed high responses in the TTR-TRβ CALUX® assay and had the largest contributions to the PFOA-EQs in the AFFF surfactants and CMS applications. Using potency factors as determined in the TTR-TRβ CALUX® to convert PFASs assessed by chemical analysis to PFOA-EQ led to comparable results as compared to the results from PFASs measured directly by the TTR-TRβ CALUX® assay. This study supports the claim that semiquantitative effect- and group-based in vitro CALUX bioanalysis tools can be applied effectively to assess industrial products containing complex mixtures with PFAS compounds for which no instrumental analysis are established, and for many compounds where in vitro toxicity data are not yet available.

Performance Test and Application Research of New Gemini Wetting Dust Suppressant

In order to solve the problem of low efficiency of dust-catching by water mist to the hard-to-wetting and respirable dust, a new wetting type dust suppressant of Gemini was proposed based on the analysis of the wetting effect of water mist. Based on the evaluation indexes of surface tension, contact Angle, wetting and settling rate of dust spray, the performance of polyquaternary ammonium salt AG-101, dodecanol polyoxyethylene etheryl dimethyl ammonium chloride, octyl alcohol polyoxyethylene etheryl dimethyl decyl ammonium chloride and macromolecular cationic PCD Gemini surfactants were optimized, and had carried on the dust-suppression performance in a certain open-pit iron mine field experiment research. The results show that the comprehensive dust suppression performance of mass concentration of 2.0% of quaternary ammonium salt polymer AG-101 is the best, indoor experimental tests showed the dust rate is 4.2 times the speed of water, the field test showed that the initial wetting speed is 4.4 times the speed of water, and the action time of dust and water mist suppression is shortened obviously. The field application proves that the total dust removal efficiency is 82.3% (water is 56.6%), which is 45.4% higher than that of water. The dust removal efficiency of respirable dust is 92.1%, which is 16.5% higher than that of water. The research results provide a new dust suppressing agent for optimization of mine spray dust removal.

Research on explosion suppression technology of low-concentration gas transmission pipeline

In order to effectively control the explosion accident disasters of low-concentration gas transmission pipelines and improve the safety of low-concentration gas transmission and utilization process, the paper has summarized and analyzed the current three types of low-concentration gas transmission pipeline explosion suppression technologies and devices used in the field, including powder suppression, inert gas suppression and fine water mist suppression, and put forward the problems of coal mine gas transmission pipeline explosion suppression technologies. It is of great practical significance to pipeline transmission and utilization of low-concentration gas.

Role of hydrogenated moiety in redox treatability of 6:2 fluorotelomer sulfonic acid in chrome mist suppressant solution

6:2 Fluorotelomer sulfonic acid (6:2 FTS) is used as alternative to perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) for different purposes such as chrome mist suppressant (CMS) and active ingredient in fire-fighting foams. In this study, degradability of 6:2 FTS under ultraviolet/persulfate (UV/PS) and ultraviolet/sulfite (UV/SF), which are typical technologies for advanced oxidation and reduction, were investigated respectively. Due to the hydrogenated moiety, 6:2 FTS was decomposed completely by UV/PS within 10 min, forming a mixture of short-chain perfluoroalkyl carboxylic acids with variable chain length (2-7 carbon atoms). Such oxidation products account for > 50% organofluorine of 6:2 FTS unmineralized portion. 6:2 FTS degradability under reductive UV/SF system was dramatically slowed down by the hydrogenated moiety, which lowered electron affinity and, consequently, reactivity with aqueous electron (eaq‾) produced by UV/SF. Fluorine mass balance showed that degradation intermediates were almost negligible: most of decomposed 6:2 FTS fluorine was converted to fluoride. A real 6:2 FTS-based CMS solution prepared from a commercial product was also tested. Both types of treatment were effective and in good agreement with the trends observed for tests with sole 6:2 FTS. Moreover, experimental results highlighted a remarkable amount of identifiable (like 4:2 FTS, 8:2 FTS and other per-/polyfluoroalkyl substances) and unidentifiable components in the CMS mixture. Indeed, fluoride concentration under UV/SF (73.8 mg/L) and UV/PS (44.9 mg/L) treatment were both higher than the estimated total concentration (<23 mg/L, according to 6:2 FTS concentration). Results strongly suggest that an oxidation pretreatment followed by reduction might be a better way to degrade and defluorinate 6:2 FTS and other precursors with non-fluorinated moieties, rather than employing single reduction or oxidation technology.

Analysis of the Impact of Water Flow Rate on the Temperature Variability in a Closed Room during the Extinguishing of A-Group Fire Using a Hybrid Water Mist Suppression System

The advantage of hybrid fire suppression systems is that they combine the advantages of both water mist and clean agent systems. Currently, this innovative technology is increasingly used in fixed firefighting systems. Available literature both in Polish and around the world describes this issue in a fragmentary way. Extinguishing system tests were carried out at the Main School of Fire Service in Warsaw. The impact of water mist flow rate on the temperature variability in a closed room during the extinguishing of group A fires using a hybrid water mist system was analyzed. Four different flow rates 0.5, 1.0, 1.5 and 3.0 dm3/min were applied. The temperature variability of selected points of a closed test chamber during extinguishing process are presented. The extinguishing efficiency, taking into account extinguishing time, average speed of temperature drop and other parameters, was estimated on the basis of proposed original criterion. The results obtained showed that water flow rate has a significant impact on temperature variability and included the determination of optimal water flow rate at which the extinguishing efficiency is the highest. The conducted research proved that the hybrid system is more effective than classic mist and gas systems when extinguishing group A fires.

A Review of Lithium-Ion Battery Fire Suppression

Lithium-ion batteries (LiBs) are a proven technology for energy storage systems, mobile electronics, power tools, aerospace, automotive and maritime applications. LiBs have attracted interest from academia and industry due to their high power and energy densities compared to other battery technologies. Despite the extensive usage of LiBs, there is a substantial fire risk associated with their use which is a concern, especially when utilised in electric vehicles, aeroplanes, and submarines. This review presents LiB hazards, techniques for mitigating risks, the suppression of LiB fires and identification of shortcomings for future improvement. Water is identified as an efficient cooling and suppressing agent and water mist is considered the most promising technique to extinguish LiB fires. In the initial stages, the present review covers some relevant information regarding the material constitution and configuration of the cell assemblies, and phenomenological evolution of the thermal runaway reactions, which in turn can potentially lead to flaming combustion of cells and battery assemblies. This is followed by short descriptions of various active fire control agents to suppress fires involving LiBs in general, and water as a superior extinguishing medium in particular. In the latter parts of the review, the phenomena associated with water mist suppression of LiB fires are comprehensively reviewed.