Remote extinguishing of large fires with powder aerosols

A new method for distant extinguishing of fire spreading in an extended closed volume such as a mine working, storehouse, subway tunnel, electric cable channels, etc. is proposed. A novel extinguishing agent based on a stable mixture of superfine ammonium phosphate [NH₄H₂PO₄] and modified fumed silica [SiO₂–CH₃] is supplied to the fire by a powerful ventilator. The properties of the extinguishing agent (average particle size, airborne residence time, distance of transfer by the air stream) have been studied in an experimental chamber (100 m³). A test extinguishing of a large‐scale fire has been performed in an experimental tunnel 180 m in length. Extinguishing agent consumption, dynamics of temperature change over the tunnel length and composition of fire gases were recorded in this test. The influence of foam concentration, addition of nitrogen and halons to aerosol, were also studied. Copyright © 2006 John Wiley & Sons, Ltd.     

D类干粉灭火系统在烷基铝类化学品消防中的应用

对烷基铝类火灾的特点与灭火剂种类选择等进行了分析,结合异戊橡胶装置中烷基铝类催化剂配制区固定干粉灭火系统的消防保护工程设计实例,从D类干粉灭火系统原理、系统设计、系统组成等几个方面进行了较为详细的阐述,期望为今后类似工程的消防设计提供经验和指导。     

Study on the relationship between the particle size distribution and the effectiveness of the K‐powder fire extinguishing agent

The relationship between the particle size distribution and the extinguishing effectiveness of the new K‐powder fire extinguishing agent has been studied experimentally, to explore the reason of the great extinguishing efficiency exhibited by the new K‐powder fire extinguishing agent on Class B fire (liquid fuel fire). The results of the experiment showed that the extinguishing effectiveness increased along with the decrease of the particle size distribution. In addition, a sharp discontinuity appeared around the limiting size, about 40 μm. The powder with the particle size below 40 μm exhibited highly effective extinguishing with the minimum effective extinguishing concentration C_xr = 23 g·m^?3, while the powder with the particle size above 40 μm exhibited little fire extinguishing efficiency. Compared with other fire extinguishing agents produced by different substances, the new K‐powder fire extinguishing has the bigger limiting size. That means, in the same particle size distribution, the new K‐powder fire extinguishing agent contains more highly effective powder than others contain, and is more effective.     

Investigation of flame retardancy and physical–mechanical properties of zinc borate/boric acid polyester composites

The glass fiber reinforced polyester composite materials were prepared with varying contents of boric acid, zinc borate, and magnesium hydroxide as flame retardants to improve the flame retardancy of the composites. Experimental results showed that boric acid exhibited a good flame retardant effect on the polyester composite. When boric acid content is used as 15 wt %, the Limiting Oxygen Index (LOI) value of the composite reached upto 25.3. The increase in boric acid content from 15 to 30 wt %, the LOI values of composite were enhanced from 25.3 to 34.5 by 9.2 units. The LOI values of the composite samples increased with increasing boric acid content. The smoke density results showed that the addition of glass fiber and flame retardants decreased the smoke density of the unreinforced polyester resin. The mechanical properties of the composites have decreased by the addition of flame retardants. The scanning electron micrographs taken from fracture surfaces were examined. The flame retardants, such as boric acid, were well dispersed in the glass fiber reinforced polyester composites and obviously improved the interfacial interaction between glass fibers and polyester composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

化学组分对干水灭火剂流动性与保水性的影响

干水（dry water）是微水滴颗粒被纳米级疏水性二氧化硅颗粒包覆层封装形成的、整体呈固体粉末状的粉体材料,其颗粒内含水量可高达98%,内部水分可以通过高温蒸发和外力挤压作用释放出来,是很有潜力的特种灭火新型材料。干水灭火剂的核心是功能性化学灭火组分,本文设计并制备了包覆不同功能性化学灭火组分的系列干水灭火剂,并测定表征了所制备干水灭火剂的粒径分布、流动性与保水性,研究了不同功能性化学灭火组分对干水灭火剂储运性能的影响。结果表明,不同功能性化学灭火组分的加入能够在一定程度上提高干水材料颗粒的流动性和保水性,其中磷酸二氢铵干水的流动性最优,氯化钠干水的保水效果最好。研究对干水灭火剂的制备、储运与使用具有重要意义。     

Experimental assessment on LPG fire extinguishing properties of three chemical powders before and after milling action

The extinguishing performance of three dry chemical powders (DCPs) was investigated through a lab-scale suppression system for liquefied petroleum gas (LPG) fire. The magnesium hydroxide (Mg(OH)₂ ), sodium bicarbonate (NaHCO3 ), and commercial ABC − MAP powders are used to prepare two groups of samples: raw samples and milled samples. The effect of milling action on the properties of DCPs, such as the bulk density, microstructure, particle size, thermal decomposition, and the extinguishing performance, is analyzed. The density test revealed that the bulk density increased after milling, and the Mg(OH)₂ had a lower density than the other powders. The microstructure analysis showed that the milled powders had a smaller particle size and more regular shapes than raw powders. The thermal analysis demonstrated that the powder decomposition process was somewhat similar with a slight difference in initial decomposition temperature and degradation rate. The fire tests proved that the extinguishing efficacy greatly improved after the samples were milled. Moreover, the experiments indicated that the milled Mg(OH)₂ was superior in fire extinguishing to the other samples with shorter extinction time and less agent quantity consumed. Based on the results, it can be inferred that the milling action has a significant influence in enhancing the extinguishing mechanisms' efficiency of DCPs.     

蛭石粉末及离子溶液改性后膨胀率和灭火有效性分析

为了研发高效干粉灭火剂粉体,提升干粉灭火剂的灭火效果,本文以蛭石粉为研究对象,采用NaCl、NaHCO₃、MgCl₂和KCl四类离子溶液对不同粒径的蛭石粉进行改性处理,并分析了原始蛭石粉末以及改性后的蛭石粉的膨胀率和表面微观结构。随后开展了ABC干粉灭火剂、未改性蛭石粉、MgCl₂改性蛭石粉、NaCl改性蛭石粉、KCl改性蛭石粉、NaHCO₃改性蛭石粉扑灭油池火实验,分析了灭火时间、灭火剂用量以及复燃情况。研究结果表明：粒径150 μm的蛭石粉末膨胀率最大,且经过改性的蛭石粉末的膨胀率要明显大于原始蛭石粉末,其中MgCl₂改性后的蛭石粉膨胀率最大,接近2.4左右;从灭火时间来看,灭火效果从低到高依次为ABC干粉灭火剂、未改性蛭石粉、MgCl₂改性蛭石粉、NaCl改性蛭石粉、KCl改性蛭石粉、NaHCO₃改性蛭石粉;从灭火剂用量角度可得出：改性蛭石粉灭火用量要明显小于未改性蛭石粉。其中,NaHCO₃改性蛭石粉用量与ABC干粉灭火剂用量相对接近。从复燃角度来看,膨胀蛭石粉末的密度较小,可长时间悬浮在油品表面,有效阻止复燃,效果明显优于传统的ABC类干粉灭火剂。     

Improving the flame retardancy of polypropylene by nano metal–organic frameworks and bioethanol coproduct

In this work, a novel flame retardant system based on nano zeolitic imidazolate framework‐8 (ZIF‐8) and the distiller's dried grains with solubles (DDGS) without traditional flame retardants has been designed and blended with polypropylene (PP) to prepare the green flame retarded composites. The influences of nano ZIF‐8 and DDGS on mechanical properties and flame retardancy of PP are studied. The results indicate that combination of nano ZIF‐8 and DDGS improves the mechanical properties of PP, and the tensile strength of the composites containing 29 wt% of DDGS and 1 wt% of nano ZIF‐8 reaches 34.0 MPa compared with 24.7 MPa of pure PP. The limiting oxygen index (LOI) of the composites containing 27 wt% DDGS and 3 wt% of nano ZIF‐8 is about 25.0% compared with 17.5% of pure PP. Besides, its horizontal burning velocity also decreases significantly. The char residues after burning of the PP composites are analyzed, and the mechanism is discussed in detail.     

Increase in flame retardance of glass‐epoxy laminates without halogen or phosphorous compounds by simultaneous use of incombustible‐gas generator and charring promoter

Highly flame‐resistant glass‐epoxy laminates without flame‐retarding additives such as halogen and phosphorous compounds have been developed to overcome environmental problems caused by these additives. The laminates consist mainly of a self‐extinguishing epoxy‐resin compound (phenol aralkyl), an incombustible‐gas generator (amino‐triazine‐novolac hardener: ATN hardener), and inorganic materials such as a charring promoter (zinc molybdate on talc: ZMT) and a limited amount of harmless metal hydroxide (aluminum trihydroxide: ATH). They are highly flame‐resistant and have other beneficial characteristics, including soldering‐heat resistance, humidity resistance, electronic properties, and processing advantages. These qualities make them applicable enough to replace the FR‐4 type printed wiring boards (PWBs) that are widely used today. Simultaneously using the ATN hardener and ZMT in the laminates, including the epoxy‐resin compound and ATH, greatly improved their flame retardance. We then reduced the amount of ATH to obtain even better flame retardance in the laminates. This reduction of the ATH, consequently, improved other practical characteristics such as soldering‐heat resistance, humidity resistance, and electronic properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3367–3375, 2006     

低碳醇改性无氟泡沫的性能分析与扑灭油池火的实验研究

针对现有氟碳类泡沫灭火剂关键组分PFOS因国际环境公约出于环保和健康而限用,以及现有泡沫灭火剂还存在析液速度快而影响灭火能效等问题,在前人及团队探究无氟泡沫复配方案基础上,基于火灾化学理论与表面活性剂技术,遴选碳氢/有机硅表面活性剂(LS-99/SDS)为基剂,通过引入可改善气泡聚并的低碳醇(乙醇、正丙醇和异丁醇)调控泡沫的发泡倍数和25%析液时间等性能,开展含醇泡沫和无醇泡沫的灭火对比实验,考察低碳醇引入后的泡沫灭火能效。结果表明,引入适量浓度低碳醇可显著影响LS-99/SDS复配体系的发泡倍数和25%析液时间。相比乙醇和正丙醇,当异丁醇质量分数为0.1%时,可有效延缓含醇泡沫的析液进程和降低析液速率。通过灭火过程的火焰温度测定,发现含醇泡沫作用下10 cm和20 cm高度处的火焰最大降温速率为20.1℃·s^-1和11.2℃·s^-1,相较于无醇泡沫体系降温效果显著,降温增幅分别为39.58%和14.29%。含醇泡沫灭火剂相对于无醇泡沫灭火时间缩短了3.6 s,缩短幅度为37.5%。适量浓度的异丁醇引入到无氟泡沫体系中,可有效延缓泡沫析液进程,提高泡沫体系的发泡倍数及稳泡性能,为无氟泡沫的优化设计提供了一条新路径。建立了基于25%析液时间、平均析液速度、最大降温速率和灭火时间等综合指标的灭火效果考察方法,为泡沫灭火效能的实验室评价提供了参考依据。     

低碳醇改性无氟泡沫的性能分析与扑灭油池火的实验研究

针对现有氟碳类泡沫灭火剂关键组分PFOS因国际环境公约出于环保和健康而限用,以及现有泡沫灭火剂还存在析液速度快而影响灭火能效等问题,在前人及团队探究无氟泡沫复配方案基础上,基于火灾化学理论与表面活性剂技术,遴选碳氢/有机硅表面活性剂(LS-99/SDS)为基剂,通过引入可改善气泡聚并的低碳醇(乙醇、正丙醇和异丁醇)调控泡沫的发泡倍数和25%析液时间等性能,开展含醇泡沫和无醇泡沫的灭火对比实验,考察低碳醇引入后的泡沫灭火能效。结果表明,引入适量浓度低碳醇可显著影响LS-99/SDS复配体系的发泡倍数和25%析液时间。相比乙醇和正丙醇,当异丁醇质量分数为0.1%时,可有效延缓含醇泡沫的析液进程和降低析液速率。通过灭火过程的火焰温度测定,发现含醇泡沫作用下10 cm和20 cm高度处的火焰最大降温速率为20.1℃·s^-1和11.2℃·s^-1,相较于无醇泡沫体系降温效果显著,降温增幅分别为39.58%和14.29%。含醇泡沫灭火剂相对于无醇泡沫灭火时间缩短了3.6 s,缩短幅度为37.5%。适量浓度的异丁醇引入到无氟泡沫体系中,可有效延缓泡沫析液进程,提高泡沫体系的发泡倍数及稳泡性能,为无氟泡沫的优化设计提供了一条新路径。建立了基于25%析液时间、平均析液速度、最大降温速率和灭火时间等综合指标的灭火效果考察方法,为泡沫灭火效能的实验室评价提供了参考依据。     

Pilot‐scale treatment of waste‐water from carbon production by a combined physical–chemical process

BACKGROUND: Due to its strong colour, high concentrations of fluorides and chemical oxygen demand (COD_Cr) and large amount of suspended solids (SS), the waste‐water from carbon production (WCP) seriously affects the stability of the circulating system of Guizhou Branch, Aluminium Corporation of China. In this paper, the performance of a pilot‐scale (24 m³ d^?1) combined treatment plant, consisting of chemical precipitation, coagulation, and Fenton oxidation, for the treatment of WCP was investigated. RESULTS: Lime precipitation and hydrated ferrous sulphate (HFS) coagulation, with polyacrylamide (PAM) as a coagulation aid, proved to be effective in the removal of colour (>70%), suspended solids (SS) (>90%) and fluoride (>80%) from the WCP. Subsequent Fenton oxidation combined with coagulation as a final treatment efficiently removed SS, F^?, COD_Cr, dissolved organic carbon (DOC) and colour. The average total removal efficiencies of these parameters in the pilot‐scale combined technology were as follows: SS = 98.8%, F^? = 95.7%, COD_Cr = 94.8%, DOC = 91.8% and colour = 98.3%, giving an average effluent quality: colour 24 (multiple), COD_Cr 168 mg L^?1, DOC 80 mg L^?1, F^? 38 mg L^?1 and SS 44 mg L^?1, consistent with the reusable water limits for the process. CONCLUSIONS: The current experimental results and the economic evaluation suggest that the combined process could be advantageous and feasible for the treatment of WCP. Copyright © 2009 Society of Chemical Industry     

Effect of nanofillers on the flame retardant properties of a polyethylene–calcium carbonate–silicone elastomer system

This study shows the effects of three different nanofillers on the viscosity properties and fire behavior of a halogen‐free flame retardant system. The original system, based on ethylene‐acrylate copolymer, calcium carbonate, and a silicone elastomer, shows good flame retardant properties. One of the nanofillers, montmorillonite (MMT), significantly increases the viscosity above 250^°C, resulting in reduced dripping and decreased heat release rate. The ash residue, however, is very brittle, indicating poor interactions between the MMT and other components of the system. The second nanofiller, sepiolite, shows no improvement on the flame retardant properties of the system. Reduced dripping is observed when a small amount of the third nanofiller, polyhedral oligomeric silsesquioxane, POSS, is incorporated into the system. In this case, high silica content on the surface indicates char formation originating from the POSS. However, an increased heat release is observed when POSS is used in the system. Copyright © 2010 John Wiley & Sons, Ltd.     

Effect of the addition of triphenylphosphine oxide,hexabromocyclododecane, and ethyl bromide on a CH<Subscript>4</Subscript>/O<Subscript>2</Subscript>/N<Subscript>2</Subscript> flame at atmospheric pressure

The chemical and thermal structure of a Mache-Hebra burner stabilized premixed rich CH₄/O₂/N₂ flame with additives of vapors of triphenylphosphine oxide [(C₆H₅)₃PO], hexabromocyclododecane (C₁₂H₁₈Br₆), and ethyl bromide (C₂H₅Br) was studied experimentally using molecular beam mass spectrometry (MBMS) and a microthermocouple method. The concentration profiles of stable and active species, including atoms and free radicals, and flame temperature pro.les were determined at a pressure of 1 atm. A comparison of the experimental and modeling results on the flame structure shows that MBMS is a suitable method for studying the structure of flames stabilized on a Mache-Hebra burner under near-adiabatic conditions. The relative flame inhibition effectiveness of the added compounds is estimated from changes in the peak concentrations of H and OH radicals in the flame and from changes in the flame propagation velocity. The results of the investigation suggest that place of action of the examined flame retardants is the gas phase. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 5, pp. 12–20, September–October, 2007.     

化工建设项目初期污染雨水及消防事故废水收集系统

化工企业在火灾事故时,经常会由于设施缺失或设置不合理而外排废水,从而造成了大量水体污染事件。对设计过程中如何设置收集初期污染雨水及消防事故废水的设施进行了简要介绍,重点介绍了收集系统的分类及特点、废水储存设施有效容积的确定,及设计过程中应注意的问题。     

Flame retardancy,antifungal efficacies,and physical–mechanical properties for wood/polymer composites containing zinc borate

This work aimed to examine flame retardancy, antifungal performance and physical–mechanical properties for silane‐treated wood–polymer composites (WPCs) containing zinc borate (ZnB). ZnB with content from 0.0 to 7.0 wt% was added to WPCs, and silane‐treated wood contents were varied. The polymers used were poly(vinyl chloride) (PVC) and high‐density polyethylene (HDPE). The decay test was performed according to the European standard EN 113. Loweporus sp., a white‐rot fungus, was used for antifungal performance evaluation. Antifungal performance was observed to decrease with wood content. Incorporation of ZnB at 1.0 wt% significantly increased the antifungal performance of WPCs. ZnB content of greater than 1.0 wt% lowered the antifungal properties of WPCs. The results suggested that the wood/PVC composite exhibited better antifungal performance than the wood/HDPE composite. The addition of wood flour to PVC and HDPE decreased flame retardancy, whereas the incorporation of ZnB retained the flame retardancy. ZnB was found to be more appropriate for wood/PVC than wood/HDPE as a result of hydrogen chloride generated from the dehydrochlorination reaction of PVC. The results indicated that the addition of ZnB did not affect the physical‐mechanical properties of neat polymers and the composites. Copyright © 2016 John Wiley & Sons, Ltd.     

危化品集装箱燃爆溢流火在相邻空间内的火行为特征研究

建立了危险化学品集装箱燃爆事故模型,针对事故形成的溢流火在相邻集装箱外立面受限空间内传播规律及温度场分布进行模拟研究。根据实地调研数据,分别设置了三种不同开口大小的危化品集装箱,同时研究了相邻间距为0.4、0.8、1.27 m等10余种不同工况的溢流火演化规律及温度场分布。研究提出了不同间距条件下发生火溢流行为的空气卷吸模型,并对溢流火焰高度进行了修正。研究结果表明,与燃爆集装箱开口相对的集装箱体对附近空气的卷吸效应具有限制作用,从而将影响开口溢流火行为的演化与发展。当相邻集装箱体间距小于一定值时,空气主要来自侧面卷吸,外部溢流火焰高度与温度均出现显著增加,此时对相邻叠加堆放的集装箱体损坏较大;随着相邻间距的增大,来自正面与侧面共同作用下的空气卷吸量增加,受限空间内的温度逐渐升高,溢流火焰高度逐渐降低,此时的破坏作用主要体现在对相邻集装箱体的热毁损破坏行为。     

Thermal stability,flame retardance,and mechanical properties of polyamide 66 modified by a nitrogen–phosphorous reacting flame retardant

Flame‐retardant polyamide 66 (PA66) was prepared by the polymerization between PA66 prepolymer and N‐benzoic acid (ethyl‐N‐benzoic acid formamide) phosphamide (NENP). Compared with the pure PA66, the flame‐retardant PA66 exhibited better thermal stability, as indicated by thermogravimetric analysis results. The limiting oxygen index was 28% and the UL‐94 test results of the flame‐retardant PA66 indicated a V‐0 rating when the content of the NENP prepolymer was 5 wt %. The flammability and flame‐retardant mechanism of PA66 were also studied with cone calorimetry and scanning electron microscopy/energy‐dispersive X‐ray spectroscopy, respectively. The mechanical properties results show that the flame‐retardant PA66 resin had favorable mechanical properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43538.     

An easy‐to‐obtain silicone‐containing flame retardant and its effects on the combustion of polycarbonate

A novel silicone‐containing flame retardant (HSOBA) synthesized from hydrogen‐containing silicone oil and Bisphenol A via a simple approach has been incorporated into polycarbonate (PC) matrix to study its effects on the flame retardancy. The flame retardancy of PC/HSOBA composites is investigated by limiting oxygen index (LOI), vertical burning tests (UL‐94), and cone calorimeter measurement. The LOI value of the composites is 31.7 and the UL‐94 rating reaches V‐0, when the content of HSOBA is 3 wt %. Cone calorimeter data confirm that the HSOBA acts as an effective additive functioning both as flame retardants and as smoke suppressant. Evolution of the thermal behaviors of the composites tested by TGA, the morphological structures, and the constituent of char residue after LOI tests characterized by scanning electronic microscopy‐energy‐dispersive X‐ray analysis were used to explain the possible flame‐retardant mode. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Promotion and inhibition of a hydrogen—oxygen flame by the addition of trimethyl phosphate

This paper gives results of numerical modeling of a laminar hydrogen—oxygen flame doped with trimethyl phosphate at various pressures and compositions of the combustible mixture. The calculations were performed using the PREMIX and CHEMKIN-II software packages. It was found that phosphorus-containing additives promoted the flame at subatmospheric pressures and inhibited it at atmospheric pressure. Kinetic analysis showed that catalytic recombination reactions were responsible for both phenomena. In the case of subatmospheric pressures, the promoting effect and its enhancement with increasing additive concentration were related to a flame temperature rise in the chemical-reaction zone due to catalysis of the recombination reactions by phosphorus-containing compounds. Increasing the additive concentration led to an increase in both the rate of the branching reaction H + O₂ = OH + O and the rate of the chain termination reaction, but the increase in branching reaction rate prevails, resulting in an increase in the flame velocity. In the case of atmospheric-pressure flames, where the reaction-zone temperature is close to the adiabatic equilibrium value, the additive led to an increase in the rate of decay of active flame species and, hence, to a decrease in the flame propagation velocity with increasing additive concentration. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 5, pp. 3–13, September–October, 2006.