Small-Scale Test Protocol for Firefighting Foams DEF(AUST)5706: Effect of Bubble Size Distribution and Expansion Ratio

The experimental program described in this paper sought to assess the suitability of the small scale DEF(AUST)5706 standard for measuring the suppression and burnback performance of Class B foams on pool fires. DEF(AUST)5706 is an Australian Defence standard mandatory for use by the Australian Navy, Army and Air Force. The test protocol required the measurement of the 3/4 control, extinguishment and 1/3 burnback times for a circular pan of aviation gasoline (AVGAS 100/130), 0.28 m² in surface area. The test program involved compressed-air foams (CAF) and aspirated foams of two expansion ratios, and employed two AFFF formulations: a 6% telomer concentrate and, to obtain base-line measurements, 3% PFOS FC-600 concentrate which was manufactured by the 3 M company prior to the PFOS phase out. At lower expansion (7:1), the aspirated and compressed-air foams demonstrated similar fire control performance, whilst more expanded (9:1) CAF was generally more efficient at extinguishing, but less efficient in controlling the fire. CAF formed a better seal over the fuel surface and at the hot pan walls, and these foams performed noticeably better than aspirated foam against fuel re-ignition. The paper links these observations with the underlying distributions of bubble sizes, which were measured and fitted to modified Rosin/Rammler cumulative volume distribution functions. We propose that a modified version of DEF(AUST)5706 be adopted as a universal small-scale test protocol.     

压缩空气泡沫灭火抗烧效能试验研究

为进一步量化压缩空气泡沫介质的性能特征优势,采用固定式压缩空气泡沫灭火系统,通过标准油盘火对比试验,分别考察压缩空气泡沫和常规吸气泡沫控火、灭火、防复燃、抗烧效能,并测试两种特征泡沫多项性能指标。结果表明：基于相同火灾试验模型和测试方法,两种特征泡沫均可扑灭92#汽油火,火焰均未复燃,但压缩空气泡沫在低灭火强度条件下的控火、降温、灭火、抗烧效能明显优于高灭火强度常规吸气泡沫;由基本性能指标表征出压缩空气泡沫具有更为稳固均细的膜状组织,并且低温环境对压缩空气泡沫结构群体具有维护作用,不会发生冰冻现象;采用压缩空气泡沫离散型喷头既可生成高质量泡沫灭火介质,又可对保护区域进行无盲点均匀覆盖,拓宽了压缩空气泡沫应用方式,对于后续重点开展压缩空气泡沫应用于高层、高大、高危建筑体室内消防安全论证工作具有一定的借鉴作用。     

大流量液氮泡沫灭火装备在化工园区的应用研究

介绍了液氮泡沫灭火技术原理,研究了液氮泡沫发泡倍数、析液时间、微观状态等,搭建了泡沫长距离输送管路系统,研究了液氮泡沫的长距离输送性能,通过多尺度储罐灭火实验验证了液氮泡沫灭火能力。实验表明：液氮泡沫的气泡直径在20~50 μm,气泡直径相对均匀;发泡倍数在7~8,25%析液时间在3~5 min。液氮泡沫可在消防带内输送1 000 m,无析出分层,泡沫性能保持不变。液氮泡沫较压缩空气泡沫的灭火能力提升1.6倍以上,较吸气式泡沫的灭火能力提升2.5倍以上。该大流量液氮泡沫灭火系统可用于扑救大型储罐火灾、地面池火、流淌火及大型生产装置立体火灾等。     

不同气源压缩气体泡沫灭B类火灾性能比较

采用实验室压缩气体泡沫系统，通过油盘火对比试验，分别考察基于不同气源的压缩气体泡沫对于120#溶剂油火灾的灭火性能，分析探讨适用于常规B类火灾扑救的气源类型和供气方案。结果表明，在泡沫溶液供给强度为2.5 L/（min·m²）的条件下，压缩氮气泡沫和压缩空气泡沫均可扑灭120#溶剂油火灾，都具有良好的抗烧和抗复燃性能；压缩氮气泡沫比压缩空气泡沫的控灭火性能略有提升，但二者差别不大；对于常规B类非极性燃料火灾，实际工程中有氮气源的场所建议直接采用已有供氮气设备作为供气源。     

抗溶型压缩空气泡沫灭火剂灭火试验研究

以高稳定性压缩空气泡沫灭火剂为研究对象,采用1.73 m² 标准火试验模型,对比考察了不同泡沫产生系统、不同发泡倍数以及不同燃料类型对水溶性液体火灭火及抗烧性能的影响。试验结果表明,抗溶泡沫灭火剂在压缩空气泡沫系统中的泡沫稳定性、灭火时间和抗复燃时间均显著优于低倍数泡沫系统;在压缩空气泡沫系统中,抗溶泡沫的抗烧性能随着发泡倍数的增大而降低;丙酮火的灭火难度高于乙醇火,建议在选用抗溶泡沫灭火剂时针对水溶性液体特点开展针对性的灭火试验评估。     

Potential impacts of ultra-high-pressure (UHP) technology on NFPA Standard 403

Ultra-high-pressure (UHP) technology as well as compressed air foam (CAF) and combined agent firefighting systems (CAFFS) have proven to enhance the performance of firefighting equipment using water and aqueous film forming foam (AFFF). UHP systems are capable of producing small water droplets at high velocity. As droplet size is reduced, surface area relative to mass increases, improving heat transfer. Smaller droplets however, experience greater drag, reducing throw distance. Findings indicate that on average, 150 m/s exit plane velocities result in maximum throw distances of between 4600 and 5600 orifice diameters. UHP prototype and full-scale testing conducted from 2004 to 2006 found that exit plane velocities of 150 m/s were found to produce 90–100 μm droplets, sizes considered optimal for fire extinguishment. In addition, UHP systems were able to extinguish two-dimensional fuel fires ranging in area from 81.6 to 613.8 m² using one-third the agent when compared to baseline AFFF tests, and one-tenth the NFPA 403 standard.     

移动制氮灭火装备在灭火救援实战中的设计应用

针对氮气灭火剂因投送方式单一且补给困难的行业痛点,提出了集制氮、储氮、供氮、输氮、保氮、联氮等功能于一体的移动式氮气灭火装置的设计理念和集成工艺,并将设计的移动式氮气灭火装置应用于大跨度举高喷射消防车。移动式氮气灭火装置兼具水、泡沫、粉剂、压缩氮气泡沫、氮气等灭火功能,可充分发挥“工艺处置与消防处置相结合”和“固/气和液/气灭火协同”的技战术,适用于消防水源不足和水灭火剂不适用场景的灭火救援需求。移动制氮灭火装备的研制和应用可为各类化工及特殊火灾事故的救援提供消防装备保障和灭火技战术支撑。     

A comparative study of drainage characteristics in AFFF and FFFP compressed-air fire-fighting foams

Drainage measurements are commonly used for assessing the quality, water-retention ability and stability of aqueous foams used in fire-fighting applications. A new experimental technique is proposed in this paper, for measuring the drainage rate of liquid from compressed-air fire-fighting foams. The procedure outlined here provides advancement in precision over that prescribed by the standard for low expansion foams (NFPA 11, Standard for evaluating low expansion foams, NFPA, Quincy, MA, 1998). A comparative analysis of drainage characteristics in two commonly used Class B fire-fighting foams was undertaken, from theoretical and experimental perspectives: (i) aqueous film forming foam and (ii) film forming fluoroprotein foam. It is demonstrated that even though both the foam solutions exhibited similar fundamental physical properties, the disparities in surface rheological properties cause the resulting foams to have remarkably distinct drainage and coarsening characteristics. In addition, a drainage model is outlined, which allows the explicit prediction of the time evolution of liquid holdup profiles and drainage rates in fire-fighting foams. The existing drainage model is extended to simulate fire-fighting foams made from protein based and synthetically produced surfactants.     

Rheology of fire-fighting foams

This paper examines the rheological properties of compressed-air foams and contains velocity profiles of foams flowing through straight horizontal tubes. It is shown that a master equation can be derived from the experimental data to account for a range of expansion ratios and pressures normally encountered during pumping of polyhedral-in-structure fire-fighting foams. The experimental data come from a Poiseuille-flow rheometer consisting of three stainless steel tubes 6.95, 9.9, 15.8 mm in diameter, with foam generated by mixing a pressurised solution of Class A foam with compressed air. Results are corrected for wall slip following the method of Oldroyd-Jastrzebski, which implies the dependence of slip coefficients on the curvature of the tube wall. The experimental results demonstrate the applicability of the volume equalisation method to the more expanded, polyhedral (ε>5) and transition, bubbly-to-polyhedral (5⩾ε⩾4) foams. (The method of volume equalisation was introduced by Valkó and Economides to correlate the viscosity of low expansion foams (ε<4), characterised by spherical bubbles.) The present results indicate that all data points align themselves along two master curves, depending on whether the foam consists of bubbles or polyhedral cells.     

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。     

An optimal lightweight foamed mortar mix suitable for tunnel drainage carried out using the composite lining method

In this paper, an optimal lightweight foamed mortar mix suitable is proposed for facilitating tunnel drainage carried out using the composite lining method. A physical performance evaluation and pore structure analysis is provided in order to assess the performance of different lightweight foamed mortar mix proportions with various void fractions and foam solution concentrations. Furthermore, on the basis of an in-plane permeability test that simulated the permeation of fines of soil leaking with underground water, the formation and distribution of open-cell foams by measuring the outflow characteristics and outflow volume for each mix of the nonwoven geotextile and lightweight foamed mortar, which are the existing tunnel drainage materials was examined. Consequently, a mix employing a foaming agent with a dilution rate of 2% (#1) showed a better drain performance than all the other mixes, because it had the most appropriately formed and distributed open-cell foams, the key component for tunnel drainage. In other words, the mix of dilution rate of 2% was thought to have achieved stable closed-cell foams because of the decline in the surface tension of the foams, as well as the optimal formation and distribution of open-cell foams that possess excellent permeability because of the cohesiveness between the foams. Moreover, the thickness (drainage space) of it was approximately 17 times that of the nonwoven geotextile, and because the closed-cell and open-cell foams were connected like a spider web, it could be expected to reduce the blocking of drainage caused by the fines of soil.     

固定式压缩空气泡沫系统单喷头喷洒特性及灭火效能

对5 种典型结构喷头进行了单喷头喷洒压缩空气泡沫和纯水试验,对喷洒介质在底面上的密度分布以及喷洒的泡沫25%析液时间进行比较分析。研究发现,喷头结构类型和流动参数都会影响泡沫析液特性,喷头内部旋芯会使泡沫稳定性降低;下垂式水喷头的底面分布均匀性较好,而扰流喷头和两种七孔喷头的底面分布均匀性相对较差,且下垂式水喷头和扰流喷头在更高的压力和流量条件下的底面分布均匀性降低;同时,压缩空气泡沫系统的喷头选型可以在一定程度上参考相应喷头的喷水特性。选用最优性能参数喷头,建立火灾模型,开展固定式压缩空气泡沫系统全尺寸变压器热油火灾试验,验证喷头与固定式系统的适配性。     

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。     

压缩空气泡沫扑灭变压器全液面溢油火灾试验研究

从变压器溢油火灾的产生原因出发,开展压缩空气泡沫灭变压器全液面溢油火的缩尺实验,对压缩空气泡沫喷淋系统和泡沫枪两种灭火方式进行了研究,考察了压缩空气泡沫扑灭此类火灾的优势以及火灾变化规律。研究表明,成膜型压缩空气泡沫扑灭变压器全液面溢油火是有效的,能够在高温油面形成稳定覆盖层,防止沸溢喷溅;冷却降温是灭火的关键因素,将油温降低到燃点以下,可扑灭溢油火灾并防止发生复燃。     

New Additive for Low Viscosity of AFFF/AR Concentrates—Study of the Potential Fire Performance

The aim of this study was to investigate the potential fire performance of alcohol resistant foams using a new additive developed by DuPont. The main intention of the new additive is to allow a lower amount of polysaccharide in the formulation of AFFF/AR concentrates thereby reducing their viscosity. A comparative study was performed using two similar formulations of AFFF/AR-concentrates, one traditional concentrate (designated F1) and a novel concentrate (designated F2), which contains the new additive and half the traditional amount of polysaccharide. The study, performed at SP Fire Technology, comprised small scale fire tests in combination with a series of additional tests aimed to provide detailed information about expansion and drainage characteristics, foam spread properties, the influence of heat exposure and vapour suppression capability.The study confirms the desired reduction of the viscosity of an AFFF/AR foam concentrate, using a lower amount of polysaccharide in its formulation, while with the use of the new additive, the fire performance has the potential to be similar or even better than a traditional AFFF/AR foam.     

Chemical Composition of Overhaul Smoke After Use of Three Extinguishing Agents

The effect of extinguishing agents on the composition of smoke from wood fires of different intensities was studied. Three agents were examined: water, a protein-based water additive, and a sulfonate detergent-based compressed air foam (CAF). Air samples were analyzed for volatile organic compounds (USEPA 502 list), aldehydes, polyaromatic hydrocarbons, acid gasses, CO, CO₂, SO _x , and total volatile hydrocarbons. Air concentrations of levoglucosan and methoxyphenols, which are specific products from burning cellulose and lignin, respectively, were also measured. Levoglucosan, methoxyphenols, and many of the polyaromatic compounds have not been previously reported in overhaul smoke. A solitary test with water extinguishment was repeated for an assessment of variability. HCN and acid gases were not present in significant concentrations. The principal components that contributed appreciably to short-term occupational exposure hazards were formaldehyde, acrolein, benzene, polyaromatic hydrocarbons, and carbon monoxide. When a flocculation effect that cleared air particulate occurred during the use of the protein-based water additive, air concentrations of most chemicals in the air samples were reduced.     

大型变压器泡沫灭火系统灭火试验研究

为探究当前国网系统内大型变压器灭火系统的有效性,搭建大型变压器消防灭火真型试验平台,火灾模型选用220kV实体变压器,并分别采用压缩空气泡沫灭火系统和泡沫喷雾灭火系统开展灭火试验研究,对比分析两种灭火系统的灭火有效性。试验结果表明：在相同的火灾燃烧条件下,压缩空气泡沫灭火系统在0.7 MPa的工作压力及6 L/（min·m2）的泡沫混合液供给强度下,34 s扑灭变压器火灾;泡沫喷雾灭火系统在0.7 MPa的工作压力及8 L/（min·m2）的泡沫混合液供给强度下,39 s仅剩高位油盘残火;试验证明压缩空气泡沫灭火系统的灭火性能优于泡沫喷雾灭火系统。本次试验为大型变压器的消防设计提供技术参数和试验依据。     

Visualization for Engineering Property of In-Situ Light Weight Soils with Air Foams

The objective of this paper is to evaluate both physical and mechanical properties of in-situ light weight soil with air foams using an industrial X-ray CT scanner. The specimen used in this study was in-situ SGM (Super Geo-Material) which was a light weight soil created by mixing dredged slurry with cement and air foam. This was sampled at the trial construction site of new Kumamoto seaport, Japan. Two different materials of air orientation which were surface active agent and protein were examined at the site. First of all, the effect of different kinds of air foams on the physical property of in-situ light weight soil was discussed using the results of CT scanning, in which the distributions of the density and air foams in the soil were taken into consideration. Furthermore, as a mechanical property, a series of unconfined compression tests was conducted for the in-situ specimen, and the density evolution was also investigated by scanning of the specimen during unconfined compression. Here, the effects of both distribution and size of air foams were also clarified. Finally, the effectiveness of the industrial X-ray CT scanner in geotechnical engineering was confirmed based on all these results.     

某换流变压器压缩空气泡沫灭火系统管网输送特性研究

为了深入研究压缩空气泡沫灭火系统（CAFS）管网内多相流体输送特性，利用Fluent数值模拟软件,对保护换流变压器的某压缩空气泡沫灭火系统整个管网流动输送过程进行了仿真计算。在保证数值模拟准确性的基础上，分析了管网中直管段、弯头、三通等典型区域处的流体表观黏度与压力变化。研究发现，管网内流动的压缩空气泡沫流体由于其自身参数在流动过程中会发生变化，管网的压降变化会受到发泡倍数和流量等多种因素的影响。     

基于微元体动力学的压缩空气泡沫射流轨迹研究

压缩空气泡沫喷射轨迹是影响泡沫灭火效能的关键因素之一.针对目前缺乏准确的泡沫射流轨迹模型的问题,基于质点运动学、流体力学、外弹道学理论,并结合试验数据对参数修正,提出压缩空气泡沫经消防水炮喷射轨迹的理论预测模型.采用四阶Runge-Kutta算法对泡沫射流微元体动力学微分方程进行求解,利用MATLAB软件进行泡沫射流理...