Sealability Properties of Fluorine-Free Fire-Fighting Foams (FfreeF)

This contribution compares the sealability performance of recently developed three synthetic foam formulations (that do not contain fluorosurfactants or fluoropolymers) with that of an aqueous film forming foam (AFFF). We apply the sealability methodology outlined in the Australian Defence Force Specification, DEF(AUST)5706. This methodology specifies a 0.28 m² small-scale indoor fire pan. The pan is first filled with 10 L of water and then 5 L of AVGAS (aviation gasoline, flash point of −50°C) or heptane (flash point of −4°C) is placed on top of the water. Foams were generated from a pressurised extinguisher with a foam nozzle as described in the standard’s specification, set to create foams with expansion of 4:1. The foam spread across the fuel until the entire fuel surface was covered with foam. At 5 min intervals, a lit taper was introduced into the space above the pan area by passing it twice around the surface of the foam in a circular motion at a height of approximately 15 mm from the surface of the foam. The results demonstrate differences in the sealability performance between AFFF and fluorine-free foams (FfreeF). Under laboratory conditions, with a foam blanket 1–2 cm deep, best-performing FfreeF formulation (RF6) provides about 30% of the durability of an AFFF for protection against evaporation of low-flashpoint flammable liquids. We also note in the results the significant differences among FfreeF with almost no sealability of AVGAS vapours offered by the two other formulations. Presented at the Suppression and Detection Research and Applications—A Technical Working Conference (SUPDET 2007); Wyndham Orlando Resort, March 5–8, 2007, Orlando, FL, USA.     

AFFF 对航空煤油油池火的抑灭有效性研究

按照国家标准灭火试验的要求,采用不同的泡沫喷射率对不同尺寸航空煤油油池火开展了灭火效果试验,分析油盘尺寸、泡沫喷射率对灭火效果的影响,验证固定喷射率条件下,能够扑救的最大尺寸的油盘。结果表明：当油盘面积为0.8 m2 时,泡沫喷射率为2.9 L/min 时的灭火时间比为1.3 L/min 时缩短近60 s;当泡沫喷射率为1.3 L/min 时,最大可控制1.0 m2 航空煤油油池火的90%燃烧,未能将其完全扑灭;当泡沫喷射率为2.9 L/min 时,可完全扑灭2.0 m2 及其以下的航空煤油油池火。     

甲醇和异丙醇池火泡沫灭火试验研究

对直径2.5 m的甲醇和异丙醇池火发展过程、冷却保护和泡沫灭火进行了试验研究.结果表明,异丙醇池火的发展较甲醇池火迅速;采用冷却水保护储罐罐壁能够显著抑制池火的发展和热辐射;受燃液表面和火焰的破坏作用,灭火泡沫释放至燃液表面后需经历一定延迟时间才能对池火产生影响,该延迟时间随泡沫混合液供给强度的增大而缩短;推算出直径2...     

改善泡沫混凝土吸水性能的研究

为改善泡沫混凝土的吸水性能,对内掺憎水剂F、内掺有机硅和表面刷涂有机硅等3种降低吸水率的方法进行了试验研究。结果表明,掺憎水剂F可显著降低泡沫混凝土的吸水率,内掺有机硅改善吸水性能的效果次之,刷涂有机硅的效果较差。     

改善泡沫混凝土吸水性能的研究

为改善泡沫混凝土的吸水性能,对内掺憎水剂F、内掺有机硅和表面刷涂有机硅等3种降低吸水率的方法进行了试验研究。结果表明,掺憎水剂F可显著降低泡沫混凝土的吸水率,内掺有机硅改善吸水性能的效果次之,刷涂有机硅的效果较差。     

压缩空气泡沫灭浮顶罐密封圈火灾性能研究

为了评估压缩空气泡沫系统用于浮顶罐的技术可行性，通过足尺灭火试验，研究不同供给强度和不同气液比下压缩空气泡沫对浮顶罐密封圈火灾的灭火性能，提出适宜的灭火应用参数。结果表明：在泡沫溶液供给强度为3.4 ~8.0 L/（min·m²）条件下，采用罐壁式压缩空气泡沫释放装置可以快速有效扑灭浮顶罐密封圈火灾，且不发生复燃；泡沫溶液供给强度越大，控灭火速度越快；气液比在8:1~12:1时对控灭火速度略有影响。建议实际工程中泡沫溶液供给强度不低于5 L/（min·m²），气液比不低于8:1，持续供泡时间不低于15 min。     

超轻EPS复合泡沫混凝土性能研究

通过向低水灰比高流动性水泥浆中掺入不同比例的泡沫和EPS颗粒,制备了一系列200 kg/m3超轻EPS复合泡沫混凝土,并测试了强度、吸水率、软化系数、干缩、导热系数等性能.结果表明,EPS颗粒的引入可以提高复合体系的强度,降低吸水率,提高软化系数,降低干缩,不会明显影响导热系数,表明EPS可作为制备超轻泡沫混凝土的优质填充料.     

Antifoaming effect of chemical compounds in manure biogas reactors

A precise and efficient antifoaming control strategy in bioprocesses is a challenging task as foaming is a very complex phenomenon. Nevertheless, foam control is necessary, as foam is a major operational problem in biogas reactors. In the present study, the effect of 14 chemical compounds on foam reduction was evaluated at concentration of 0.05%, 0.1% and 0.5% v/v_sample, in raw and digested manure. Moreover, two antifoam injection methods were compared for foam reduction efficiency. Natural oils (rapeseed and sunflower oil), fatty acids (oleic, octanoic and derivative of natural fatty acids), siloxanes (polydimethylsiloxane) and ester (tributylphosphate) were found to be the most efficient compounds to suppress foam. The efficiency of antifoamers was dependant on their physicochemical properties and greatly correlated to their chemical characteristics for dissolving foam. The antifoamers were more efficient in reducing foam when added directly into the liquid phase rather than added in the headspace of the reactor.     

泡沫混凝土动态力学性能及本构关系

采用分离式霍普金森压杆(SHPB),对泡沫混凝土进行了不同最大应变率下的冲击试验.结果表明:泡沫混凝土动态应力-应变曲线均呈现出明显的应变率效应,因材料多孔结构的特殊性,整段曲线上下波动较大,在破坏阶段尤为明显;应变软化阶段中应力值并没有快速下降至完全丧失承载力,而是形成了较高的应力平台,并且最大应变率越高,应力平台越长、越显著.从破坏层面分析,较低最大应变率下泡沫混凝土主要呈均匀压实破坏;较高最大应变率下则呈现逐层塌落的破坏形式.借鉴宏观损伤变量及朱-王-唐本构方程,归纳宏观试验结果,通过改进建立了反映泡沫混凝土峰值应力前动态应力-应变关系的等效本构方程.     

复合掺合料对泡沫混凝土防水抗渗性能的影响

研究了水胶比和复合掺合料对700级泡沫混凝土抗压强度、吸水率及防水抗渗性能的影响,结果表明,水胶比为0.45~0.50时,制备的700级泡沫混凝土的抗压强度较高;粉煤灰和矿粉复合、粉煤灰和石灰石粉复合能提高泡沫混凝土的抗压强度和抗渗性能、降低吸水率,质量吸水率最高能降低25%,体积吸水率最高能降低24%,抗渗高度能降低5 mm;但粉煤灰和硅灰复掺、石灰石粉和硅灰复掺对泡沫混凝土的抗压强度不利,且对泡沫混凝土的抗渗性能提高不明显。     

阻燃泡沫保温材料燃烧特性研究

分析了对建筑材料燃烧特性研究的方法和原理，确定了依照耗氧原理进行燃烧特性研究的方向，以热释放速率（HRR）、燃烧增长速率指数（FIGRA）、热释放量（THR）为评价参数进行分析。以泡沫保温材料为试验样品，采用中国现行的燃烧性能分级体系同欧洲最新分级体系规定的试验方法进行比较，并对不同原理得到的研究结果进行比较。     

压缩空气泡沫灭变压器升高座溢油火性能

通过缩尺灭火试验,研究压缩空气泡沫对变压器升高座溢油火灾的灭火有效性,分析提出适宜的灭火应用方式及应用参数。结果表明,压缩空气泡沫可有效扑灭变压器升高座溢油火灾,具备良好的灭火和抗复燃能力;在泡沫溶液供给强度为11.4 L/（min · m 2 ）条件下,灭火时间为 3.9 min,连续供泡 10 min,将油温降至变压器油燃点以下,且灭火后不发生复燃;提高泡沫溶液供给强度可以提高灭火与降温速度。实际工程中建议采用压缩空气泡沫喷淋系统和稳定性高的压缩空气泡沫,且释放装置与管网应采取抗爆炸冲击措施。     

典型泡沫灭火装备喷射性能试验研究

通过筛选典型泡沫灭火装备和泡沫灭火剂,开展了基于喷射试验的装备性能评估研究,结果表明,在产品检测过程中只采用单一来源单一种类泡沫灭火剂进行测试,难以全面评估泡沫灭火装备喷射性能;泡沫枪和消防炮的喷射性能与泡沫类型相关性较大,对AFFF的适配性较好,不同厂家的同类型AFFF喷射性能差异较小;采用吸气式和非吸气式炮头对于消防炮喷射的泡沫性能影响较小。     

Experimental study and implementation of a novel internal foam spraying system for roadheaders

Foam technology utilizes the good coverage of foam to form a closed space around dust sources. The foam then wets the dust particles, causing them to adhere before they spread into the air, resulting in better dust control than with water sprays. In the process of foam dust control at a heading face, the foam spray trajectory is highly influenced by the wind, making it difficult to focus foam on the dust sources, which wastes the foam and reduces dust control efficiency. To resolve this problem, the idea of transporting foam to the cutting head through the roadheader’s inner pipeline is proposed. To adapt to the high resistance of foam delivery in the roadheader’s inner pipeline, according to the water and air supply of the heading face, a table water-jet suction device and porous spiral coupling foaming device were designed, and the working conditions were tested using a self-designed experiment system in the laboratory. The results showed that the foaming agent could be automatically added into the device at a working water flow rate of 1–1.6 m³/h at a ratio of 1%. The optimum air flow was 45–50 m³/h, in which range the foam expansion ratio reached the maximum and the outlet pressure demand was satisfied. Field application showed that the new foam method had a better dust control efficiencies than traditional foam methods.     

Rigid foam polyurethane (PU) derived from castor oil (Ricinus communis) for thermal insulation in roof systems

This paper discusses the response of the thermal insulation lining of rigid foam polyurethane (PU) derived from castor oil (Ricinus communis) in heat conditions, based on dynamic climate approach. Liners have been widely used, because the coverage of buildings is responsible for the greatest absorption of heat by radiation, but the use of PU foam derived from this vegetal oil is unprecedented and has the advantage of being biodegradable and renewable. The hot wire parallel method provided the thermal conductivity value of the foam. The thermogravimetric analysis enabled the study of the foam decomposition and its lifetime by kinetic evaluation that involves the decomposition process. The PU foam thermal behavior analysis was performed by collecting experimental data of internal surface temperature measured by thermocouples and assessed by representative episode of the climatic fact. The results lead to the conclusion that the PU foam derived from castor oil can be applied to thermal insulation of roof systems and is an environmentally friendly material.     

An experimental study of the use of liquid argon and argon-filled aqueous foams for the extinction of lithium fires

The lithium pool temperatures of a 10-g lithium fire in an insulated container approximate the lithium pool temperature (above 1000°C) of a large-scale lithium fire. Addition of water or air-filled aqueous foam to a large-scale lithium fire generally results in a violent reaction. This violent reaction was observed when water or air-filled aqueous foam was added to an insulated 10-g size lithium fire.The use of a liquid argon spray against an insulated 10-g lithium fire resulted in substantial spattering of the hot, molten lithium. Consequently, a liquid argon spray is not recommended against a large-scale lithium fire.Although an argon-filled aqueous foam directed onto an insulated 10-g lithium fire resulted in an increase of the lithium pool temperature, in every experiment conducted in this effort the lithium fire was extinguished. The extinguishing action of the argon-filled foam is positively correlated to the foam flow rate directed to the fire. Aqueous argon-filled foams from concentrated sodium silicate solution or cupric chloride solution did not appear to enhance the extinguishing action of the foam, compared to argon-filled water (only) foams.     

改性膨胀玻化微珠对三相泡沫性能的影响

采用两种不同物化性质的氟碳表面活性剂对膨胀玻 化微珠进行表面改性,研究其表面特性对三相泡沫的发泡性、泡沫 稳定性、油气密封性和抗烧性能的影响。研究结果表明：固水接触 角在 0~90o ,膨胀玻化微珠疏水性增强（即接触角增大）有助于改 善三相泡沫的发泡性和泡沫的稳定性;膨胀玻化微珠表面疏油性 强于疏水性对改善油类三相泡沫灭火剂的泡沫稳定性、油气密封 性及抗烧性能更有效;改性后的三相泡沫排液期间气体不容易排 出体系,而是在三相泡沫和汽油之间形成水气两相泡沫区,可持续 近 10 h,气体最终在三相泡沫和杯壁结合处（最薄弱的地方）完全 释放,表明三相泡沫极其致密和稳定。     

Biodegradability of Firefighting Foams

The aim of this study was to evaluate and compare the biodegradation susceptibility of seven different types of foam concentrates (four synthetic and three protein based) used in Europe. The biodegradation of 40 foam concentrates was measured according to OECD 301 F Guideline, based on the CO₂ evolution by the activated sludge during 20 days at 20°C. The foam concentrates were applied at concentrations equivalent to COD = 1000 mg O₂/l. Unexpectedly, the biodegradation rate of the synthetic foam concentrates was higher compared to the protein based ones. Although slight differences exist among the results, a rough order of the foam concentrates biodegradation susceptibility can be established as follows: S > AFFF > Class A > AFFF-AR > FFFP > FP > P.     

Assessment of the fire toxicity of building insulation materials

A significant element in the cost of a new building is devoted to fire safety. Energy efficiency drives the replacement of traditional building materials with lightweight insulation materials, which, if flammable can contribute to the fire load. Most fire deaths arise from inhalation of toxic gases. The fire toxicity of six insulation materials (glass wool, stone wool, expanded polystyrene foam, phenolic foam, polyurethane foam and polyisocyanurate foam) was investigated under a range of fire conditions. Two of the materials, stone wool and glass wool failed to ignite and gave consistently low yields of all of the toxic products. The toxicities of the effluents, showing the contribution of individual toxic components, are compared using the fractional effective dose (FED) model and LC₅₀ (the mass required per unit volume to generate a lethal atmosphere under specified conditions). For polyisocyanurate and polyurethane foam this shows a significant contribution from hydrogen cyanide resulting in doubling of the overall toxicity, as the fire condition changes from well-ventilated to under-ventilated. These materials showed an order of increasing fire toxicity, from stone wool (least toxic), glass wool, polystyrene, phenolic, polyurethane to polyisocyanurate foam (most toxic).