电熨斗过热故障火灾痕迹与火烧痕迹的对比分析

文章对电熨斗过热故障的火灾痕迹与火烧过程中遗留的痕迹特性进行了分析,通过对比发现,过热故障导致的火灾痕迹,无论在宏观形貌还是硬度分布等方面,均显著区别与火烧电熨斗的火灾痕迹.在现场勘查及物证提取与鉴定中,可依据分析的结果来判断火灾是否由电熨斗引起,进一步为火灾原因调查提供新的调查依据.     

火场中电熨斗残留物的形貌特征分析

本文模拟电熨斗正常使用、通电过热使用、直接受火灾作用、正常使用后受火灾作用、通电过热后受火灾作用,获得电熨斗在不同条件下的试验样品,利用扫描电镜观察电热丝的微观形貌特征,并进行对比分析.为公安消防机构认定火灾原因和明确火灾责任提供了一种新的鉴定依据和方法.     

小家电的火灾预防

一、电熨斗 电熨斗使用完毕忘记切断电源,或者设置不当,极易引发火灾。经测试,300瓦、500瓦、700瓦的电熨斗,表面温度可分别达到520℃、600℃、620℃。因此,将正在通电使用的电熨斗放置在可燃物体上,只要稍一疏忽或临时有事离开,往往仅几分钟,就能引起火灾。     

如何根据火灾痕迹寻找起火点

如何根据火灾痕迹寻找起火点最高人民检察院法纪检察厅孙佩生火灾是残酷的，也是无情的。但火灾的发生、发展过程是有规律的。如可燃物、助燃物的燃烧痕迹就是确定起火点的重要依据。认真研究分析各种燃烧痕迹的特征和形成条件以及可能造成起火的各种因素，就能较为准确地...     

基于火灾调查中痕迹采用的有关思考

现如今,人们在防火安全方面的意识在逐步增强,对火灾预防的重视度也越来越高。而要提高火灾的预防效果,就需要对火灾出现的原因、具体过程等内容有一个系统的了解,从而采用有效的预防措施来防范,并为火灾自救、营救提供参考依据。在此过程中,火灾调查中的痕迹作用也逐渐显现出来。基于此,本文从火灾调查中痕迹的主要作用入手,对其应用的具体步骤进行探讨,希望能够对火灾调查提供一些参考依据。     

ZR-BV单芯铜线过电流故障电弧熔痕特征研究

为准确认定电气火灾事故中的过电流故障,模拟在不同电流条件下ZR-BV单芯铜线的过电流故障,通过逐帧分析高速影像研究导线发生过电流故障时的变化过程,使用金相分析技术分类研究过电流导线电弧熔化痕迹的组织特征。结果表明:当I≥4Ie时,导线发生熔断,断路电弧将引燃热分解后的绝缘热解气体,造成火灾的蔓延扩大;过电流导线电弧熔断痕与火烧熔痕的宏观特征较为相似,但喷溅熔痕和发散状熔痕是过电流导线所特有的;枝晶偏析组织是过电流电弧熔断痕的典型组织,且随着电流值的升高,枝晶偏析组织分布范围明显扩大,几乎不再出现等轴状组织。     

数值模拟方法在壁面烧损痕迹的应用

本文作者对FDS源程序进行了改进，并利用改进后程序计算火灾过程中壁面热解形成图痕，作为火灾调查的方法之一，初步分析壁面烧损痕迹发展特征。该方法可以根据火灾场景、壁面材料、起火点功率的不同计算研究壁面燃烧痕迹形成规律，并提出使用该方法对火灾调查提供理论依据的可行性和重大意义。     

火灾调查中物证损坏原因及防范措施探讨

火灾证物对火灾案件调查的重要性众所周知,通过对火灾证物的取证和分析可以找到火灾产生的原因和发展情况,这些火灾现场的物品和痕迹也是消防部门制定有效防灾计划的重要依据。火灾可以说是在人们生活中经常出现的一种严重事故,但是在火灾扑救时会对现场的物品或者痕迹造成损坏,给火灾调查增加了难度。本文通过分析火灾调查中物证损坏的原因,科学合理地提出一些防范措施,有效提高火灾调查的工作效率。     

火灾痕迹物证的发现提取与检验

收集火灾现场痕迹物证是火灾事故调查中认定火灾原因,明确火灾性质的重要工作,本文结合火场勘察的实践经验,对火灾痕迹物证的发现和提取工作进行了总结,对火灾痕迹物证的检验方法和要求做了简要说明。     

导线电缆火灾特性分析

导线电缆是用于传输电能、传递信息和实现电磁能量转换的电工产品.但当其在过载、短路、局部过热等故障状态及外热作用下就会引起绝缘材料绝缘电阻下降、失去绝缘能力、甚至燃烧,进而引发火灾爆炸事故.因此,深入研究导线电缆的火灾特性,找准致灾因素,对于制定科学合理的防火对策,减少火灾损失,具有重要意义.本文以最常见的聚氯乙烯绝缘导线电缆为代表,讨论导线电缆的火灾特性.     

电动汽车锂离子电池组火灾数值模拟研究

为了探究电动汽车火灾危险性，利用FDS软件建立锂离子电池火灾模型，并对电动汽车锂离子电池组火灾进行数值模拟研究，分析火灾过程中的热释放速率、烟气、能见度、温度、CO和CO2浓度变化规律。研究结果表明:电动汽车内锂离子电池组火灾发展迅速，其烟气、高温、CO等危害影响车内人员的安全；车辆内部锂离子电池组的数量决定其火灾危险性的大小，大电池容量电动汽车火灾风险较高；当电动大巴车后端电池组发生火灾时，人员后门逃离的安全性系数高于前门；电动汽车火灾可能发生蔓延，增大车辆密集型区域的消防安全难度。该模拟结果可为电动汽车消防提供参考。     

API Standard 521 new alternative method to evaluate fire relief for pressure relief device sizing and depressuring system design

Since the 1950's, API Standards have provided guidance on determining relief loads for equipment exposed to pool fires. The API method is empirical based on tests performed in the 1940's. There is increasingly widespread interest in analytical methods based on heat transfer principles to model fire heat input. The API committee agreed to include an analytical method in the 6th edition of API Standard 521 to establish relief loads for pressure relief devices and to design depressuring systems for the fire scenario. The analytical method provides more flexibility than the empirical method but has limitations (e.g., too many permutations are possible leading to potential under-sizing of the pressure relief device).This paper discusses the basis for the empirical method in API Standard 521 and provides comparisons of the empirical and analytical method with two more recent large-scale pool fire tests. This pool fire test data indicates that the empirical method will provide a conservative estimate of pool fire heat input for most applications and is still the method of choice when designing pressure relief systems. However, these recent tests indicate the empirical method needs to be modified when a vessel or equipment is partially confined by adjacent embankments or walls equal or greater than the vessel height. In such cases, the wetted area exponent should be 1.0 instead of 0.82.The analytical method is useful in determining time-versus-temperature profiles for heating unwetted vessels of varying wall thicknesses and materials of construction. These profiles, which depend upon the type of fire (e.g., unconfined pool fire, jet fire, etc.), can be combined with tensile strength and stress-rupture data to specify a depressuring system's pressure-versus-time profile. This will minimize failure and/or mitigate the effects of failure due to overheating from fire exposure.     

电气火灾残留物的SEM分析方法研究

通过分析电气火灾的形成原因,总结出该类型火灾的残留物种类。然后利用电焊机和电阻炉等设备分别制备出铜铝导线的一、二次短路熔痕和火烧熔痕,电热丝的通电过热和火烧熔痕,并运用了目前一种新式有效的显微结构分析工具——扫描电子显微镜,对以上样品的表面进行微观形貌的观察、比较与分析。通过分析讨论,可以发现电气火灾残留物在火灾前后其表面的微观形貌特征存在明显不同。根据这些特征能够很轻易的鉴别出电气设备在火灾发生前的使用状态,从而推断出火灾是否由该电气设备引发而起。此项结论能够为从事火灾调查的人员对电气火灾原因的准确认定提供可靠依据,也能够为扫描电子显微镜技术的应用领域进行拓宽提供一些帮助。     

Reliability evaluation of fire alarm systems using dynamic Bayesian networks and fuzzy fault tree analysis

In almost all industries, fire alarm systems play a vital role in the reducing the risks associated with fires and damages. Therefore, it is necessary to evaluate their reliability and performance in emergency situations. The present study aimed to use fault tree analysis (FTA) to determine the root causes involved in the failure of fire alarm systems, to use Fuzzy set theory and expert elicitation to determine relative probabilities, and finally, to evaluate the reliability of a fire alarm system using dynamic Bayesian networks (BNs) during a thirty-six months period. A total of 29 basic events were detected from the FT. The reliability of the fire alarm system was estimated at 0.954 according to the FT and 0.957 according to conventional BNs. The reliability of the fire alarm system after 36 months was estimated at 0.375 according to dynamic BNs. All the events involved in the failure of fire alarm systems were drawn in the fault tree diagram. The results indicate that remodeling of these systems and simultaneous construction activities are the most important factors in the failure of the fire alarm system. System reliability can also be increased to 0.965 by providing preventive and control measures to reduce the probability of critical events.     

硫化亚铁引发储油罐火灾危险性的研究

笔者通过模拟储油罐中硫化亚铁的生成方式 ,分析和研究了硫化氢气体与氢氧化铁、三氧化二铁和四氧化三铁反应 ,生成的硫化亚铁的氧化倾向性 ,并采用自然氧化绝热装置 ,测定了硫化亚铁的温度变化曲线。实验研究结果表明 ,不同方式生成的硫化亚铁 ,其氧化性不同 ,自燃性也不同 ,均有较显著差异。硫化亚铁的温度变化曲线表明 ,氧化反应随着时间增加 ,其他应进行得越来越快 ,将会造成热量的聚集 ,使油品温度快速上升 ,导致油品自燃和储罐发生着火爆炸。实验研究证明 ,硫化亚铁氧化反应放出热量是构成油罐着火危险性的最大因素。     

靶式流量计在火灾烟气流速测量中的应用

分析了几种传统气体流速测量仪器的原理及其应用于火灾烟气测速时的缺陷,介绍了靶式流量计的工作原理及应用靶式流量计测量火灾烟气流速的方法.利用三种不同的仪器,对水啧淋作用下自然排烟口的烟气流动速度进行了试测.实验结果证明,在处理低速、中温、高湿度和多颗粒杂质火灾烟气的测速问题上,与传统方法相比,靶式流量计具有更好的适用性和明显的优越性.     

铁路隧道救援站火灾模拟实验平台设计及细水雾系统抑制车厢火灾的模拟实验研究

按照1：1尺度设计了实验平台,包括模拟隧道、模拟列车、排烟系统、火灾监控系统、火灾扑救系统以及火灾参数测量系统,是国内第一个专门对铁路隧道救援站的火灾安全性进行系统研究的全尺寸实验平台。实验平台可实现温度场、燃烧成分、火源热辐射等关键参数的测量;可研究不同工况条件下,火灾监控、火灾扑救技术和烟气控制技术的有效性,为发现火灾特征参数的演变规律和掌握有效的火灾控制技术提供了一整套解决方案,具有广阔的应用前景和重要的实际指导意义。本文建立并利用这样一个全尺寸实验平台进行了细水雾灭火系统抑制车厢火灾的模拟实验研究,获取温度、有毒有害气体浓度、热辐射等火场重要参数,发现细水雾灭火系统可有效的抑制车厢火灾,并验证了此实验平台用于铁路隧道内列车火灾实验研究的可行性和有效性。     

Factors related to injury of shiftworking fire fighters in the Northeastern United States

Fire fighters, who provide society with an essential and life-saving service, are subjected to the effects of shiftwork and to the demands (physical and mental) and dangers of their profession, all of which can contribute to injuries. To identify factors involved in injuries to fire fighters, the timing, frequency, types, and places of occurrence of injuries sustained by fire fighters in three different municipal fire departments were examined. Data was obtained from analysis of Workers' Compensation forms. The most frequent injuries involved inhalation of hazardous materials and lacerations. Ninety-two percent of the injuries occurred at the fire scene, and their causes were related to fire fighting duties, such as rescue, extinguishment and overhaul. Although only 54% of fire alarms nationwide occurred from 12:00 to 16:00 and from 18:00 to 24:00 (42% of a 24 hour day), 68% of the injuries sustained by the fire fighters studied occurred during these time periods. Per alarm, at meal time or on the night shift fire fighters were more likely to be injured. Serious injuries were more prevalent at standardly accepted meal-times. The timing of the highest frequencies of injuries suggests that, due to the shiftwork nature of firefighting, both disruption of eating patterns and fatigue increase the risk of work-related injury to fire fighters. By understanding the contribution of factors, especially human ones, such as altered metabolism (due to disruption) and fatigue (due to time elapsed since awakening, alteration/disruption of sleep-wake pattern, or hypoglycaemia), interventions can be developed, which should decrease the incidence of injuries to fire fighters.     

基于火探管式的锂离子电池灭火技术研究

为研究锂离子电池灭火方案,基于火探管灭火技术同时利用新型清洁灭火剂Novec 1230,组装成火探管灭火系统。在灭火测试平台上以功率为200 W的电热管作为外热源引发单电池或电池模组热失控,通过改变火探管的布置位置,记录相应的灭火行为以及灭火效率,并对实验结果进行了分析。研究结果表明,当火探管灭火系统直接布置在电池正上方时,在起火后的5.6s内控制火情;随着灭火剂用量增加可以显著降低体系温度,防止电池复燃以及连锁热失控现象发生;火探管有效覆盖区域外的失控电池作为热源将继续加热临近电池,引发连锁热失控,造成灭火系统失效;根据电池热失控后的燃烧行为以及传热行为,提出相应的火探管灭火系统复合方案。     

基于拉曼散射的分布式光纤定温与差温探测方法

基于拉曼散射的分布式光纤测温系统应用于火灾监测有独特的优势,弥补了传统感温探测器的不足。介绍了基于拉曼散射的测温原理及基于光时域的空间定位原理,并进行了火灾预警实验,实验结果表明当建筑物高度在一定范围内,基于拉曼散射的分布式光纤测温系统可以很好地实现火灾预警功能。