认真对待红外光束感烟探测器的安装

改革开放以来 ,城市面貌发生了巨大变化 ,不仅崛起了许多作为城市景观的高层建筑和超高层建筑 ,也新建了不少体现城市综合经济能力的大空间建筑。这些大空间建筑 ,由于安装点型火灾探测器比较困难或根本不可能 ,或为了节省投资 ,因而采用红外光束感烟探测器代替点型火灾探测器进行保护。以厦门为例 ,仅笔者最近五年接触的使用红外光束感烟探测器的建筑就有 :高崎国际机场候机楼、市政府大会堂、厦杏摩托车生产厂房、厦门航空公司维修机库、太古飞机工程有限公司一期维修机库、二期维修机库 ,正在兴建中的厦门国际会展中心和通用电气发动机服…     

格栅式吊顶场所点型感烟火灾探测器安装技术研究

通过公安部消防局项目"格栅式吊顶场所火灾探测设计安装技术研究"的研究工作,描述了在不同格栅或不同镂空比格栅条件下,探测器的安装方式、安装部位及探测效果,最终形成了格栅式吊顶场所点型感烟探测器的设计安装准则,为我国相关规范的制(修)订提供借鉴和参考依据。     

防虫网对点型感烟火灾探测器迟滞时间的影响

迟滞时间是反映点型感烟探测器对环境变化跟随性的指标，防虫网是影响火灾探测器迟滞时间的较大因素之一。通过实验研究了防虫网对报警迟滞时间的影响程度，提出了根据环境合理选择点型感烟探测器的方法。     

超高空间线型光束感烟火灾探测器安装参数

在内部高度为27m的大空间实验室开展明火实验,通过分析地面以上25m和26m两个高度烟雾浓度和温度数据及多组线型红外光束感烟火灾探测器报警情况,研究大空间内20m以上高度线型红外光束感烟火灾探测器安装参数。实验结果表明,对于内部举架高度在20～27m的超高大空间,线型红外光束感烟火灾探测器在顶棚附近安装时,相邻两组探测器光束轴线的水平间距仍不宜大于14m,宜安装在距顶棚垂直高度0.3～1.0m范围内或尽量接近顶棚安装。     

光电感烟火灾探测器抗粉尘污染试验研究

利用自研制的粉尘环境模拟试验装置开展光电感烟火灾探测器抗粉尘污染试验研究。研究表明,粉尘环境对感烟探测器的主要影响是使其响应阈值减小,灵敏度增加。点型感烟探测器污染试验后仍能保持基本功能,但独立式感烟探测器经过粉尘污染后有超过半数失去基本功能或不符合使用要求。     

线型光束感烟探测器与点型光电感烟探测器的区别

线型光束感烟探测器与点型光电感烟探测器在工作原理和实际应用方面都存在着很大的区别。虽然二者都采用红外光源感烟或探火,但其工作原理极不相同。线型光束感烟探测器通常是由分开安装的、经调准的红外发光器和收光器配对组成的;其工作原理是利用烟减少红外发光器发射到红外收光器的光束光量来判定火灾,这种火灾探测方法通常被称做烟减光法。点型光电感烟探测器的红外发光元件与光敏元件（光子接收元件）在其探测室内的设置通常是偏置设计,二者之间的距离一般在２０—２５ｍｍ,在正常无烟的监视状态下,光敏元件接收不到任何光,包括…     

独立式感烟火灾探测器的使用应引起重视

1　背景资料2 0 0 0年 5月 12日 ,美国阿拉巴马州地方法院初步通过了消费者诉 BRK有限责任公司和 Sunbeam股份有限公司生产的独立式感烟火灾探测器产品质量一案的和解方案 ,初步拟定的和解方案是由 BRK公司和Sunbeam公司向消费者赔偿 4 5 0万美元。这一诉讼历时两年 ,原因是消费者提出 ,上述公司生产的标有“First Alert”、“Family Guard”、“Wake′N Warn”、“BRK Electronics”和“BRK”商标的离子感烟型和光电感烟型独立式火灾探测器在销售时未向消费者明示其产品的局限性 ,直接或间接导致了火灾损失的增加[1] 。独立式感烟…     

点型光电感烟火灾探测器的灵敏度

对美国、欧洲、日本点型光电感烟火灾探测器（以下简称光电感烟探测器）标准所规定的火灾灵敏度试验和响应阈值试验的试验方法及要求进行比较，提出了改进光电感烟探测器灵敏度的方法。     

大空间烟雾探测报警技术——红外光束线型感烟火灾探测器及高灵敏度吸气型感烟探测器

介绍了两种运用于大空间建筑上的火灾烟雾探测报警产品——红外光束线型感烟火灾探测器和高灵敏度吸气型感烟探测器 ,详细阐述了其工作原理和应用特点 ,并对其工程使用情况做了简要说明。     

Analysis of the Response of Smoke Detectors to Smoldering Fires and Nuisance Sources

Since the initial smoke detector was developed, research has been ongoing to reduce the response times to fire sources and improve the ability of detectors to ignore nuisance sources. Research has been conducted to analyze the signatures from cooking activities, ranging from normal cooking to the flaming ignition of food products with the intent of identifying the precursors to flaming ignition. In particular, the goal of the research is to provide an alarm sufficiently prior to flaming ignition to allow homeowners to take corrective actions to prevent a fire. For the 11 experiments analyzed, the optical density measured in the range hood was the most accurate precursor signal, having the greatest ability to predict the imminent transition to a flaming fire with a minimum of false positives. Though plagued by false positives, the temperature of the heating element and response of an ionization detector provided a faster response than the optical density measure. Given that this research only included 11 experiments, further research should be conducted on a broader range of cooking styles and items being cooked.     

吸气式感烟探测器在高大空间应用的试验研究

通过实体试验,研究高大空间场所中吸气式感烟火灾探测器的不同布置方式,对于不同火源类型、不同火源位置和不同气流干扰条件的响应性能,指出在高大空间建筑中该类型火灾探测器的布防原则和方式。     

Effect of Smoke Source and Horn Configuration on Enhanced Deposition, Acoustic Agglomeration, and Chladni Figures in Smoke Detectors

A series of UL/EN based test fires was conducted in a two room/corridor enclosure to investigate the viability of methods for determining whether a smoke detector sounded under a variety of smoke conditions and to see if this methodology could be applied to a detector with a different horn configuration. The presence of enhanced deposition in the form of a black or orange-brown ring and agglomerates around the central opening of a smoke detector horn was found to be a reliable indicator that the horn sounded when it was exposed to smoke from eight standardized, single-substrate fuel sources including hydrocarbon pool, flaming polyurethane foam, and smoldering polyurethane foam fires. Determinations could generally not be made for detectors exposed to white or gray smoke generated by flaming paper, smoldering paper, flaming wood, smoldering wood, and smoldering cotton wick due to a general lack of visible soot deposition within the detector. Therefore, it is not recommended to use the absence of a black or orange-brown ring of enhanced deposition, in and of itself, as an indicator that the horn did not sound. Nevertheless, this conclusion can be reached when the absence of enhanced deposition is combined with evidence supporting the presence of flaming fuels that produce black, sooty smoke. Test series were conducted using two different smoke detector brands, each having a different horn configuration. Findings suggest that the same type of methodology for determining whether the detector sounded is applicable to both models. Chladni figures were not found on any of the smoke detectors, whether they sounded or not; hence, the absence of a Chladni figure was not an indicator that the detector did not sound. A smoke flow visualization technique was used to determine the mechanism that caused the observed enhanced deposition and agglomerates on horns that sounded during a smoke exposure. Additionally, a smoke box test series showed that the extent of observed soot deposition increased with increasing smoke exposure.     

地铁车站火灾烟气的蔓延与控制

采用FDS计算模拟了北京地铁某典型车站不同火灾情况下的三维烟气流场,结果显示,当火灾发生在离出口楼梯间较近的站厅时,烟囱效应对烟气控制起决定性的作用,并且此时不需要机械排烟.当站台中部发生火灾时,只有机械排烟和挡烟装置配合使用才可以有效地控制烟气.重点对出口通道能否满足人员疏散时温度、风速、能见度的要求进行了分析.     

水平加载方向对粘土中群桩响应影响的数值研究

利用ABAQUS有限元软件,以现场试验为原型,建立数值分析模型,对群桩原位试验进行模拟,对比了单向水平荷载作用下单桩和群桩的水平荷载位移曲线,验证了数值模型和计算参数的有效性,然后利用该土层和桩体信息,研究了在粘土中的1×2群桩、1×3群桩、2×2群桩和3×3群桩在不同方向水平荷载作用下的响应。研究结果表明,群桩中由于桩与桩之间相互影响,导致桩的水平承载力降低,其中前排桩对后排桩的影响最大,后排桩对前排桩的影响次之,而同排桩之间的影响最弱;当沿不同水平方向进行加载时,各单桩所分配到的水平力变化明显,主要取决于其所处的桩位和其他桩对该桩产生的"遮蔽效应"。     

电厂电缆层自动灭火系统适用性研究

依据没有灭火系统保护的FDS模拟计算结果,通过水喷淋保护下电缆层火灾的模拟计算与细水雾保护下的实体实验,对比常规水喷淋与细水雾灭火技术在电缆层的灭火有效性。依据电厂典型作业场所火灾及烟气的特点选择合适的灭火系统,为类似的电厂消防设计提供了参考。     

格栅式吊顶场所火灾探测器安装设计的研究

采用16只光电感烟探测器分别置于格栅吊顶上下方,以木材热解阴燃火为燃烧物研究格栅吊顶不同镂空比对探测器响应的影响.改变火源为棉绳热解阴燃火比较探测器的响应.以FDS模拟对实体实验进行补充,研究格栅安装高度、格栅厚度对探测器响应的影响.结论:镂空比小于15%时格栅吊顶下方的探测器先报警;镂空比为15%～30%是格栅吊顶上下方探测器出现交叉报警;镂空比大于30%时格栅上方探测器先报警.不同燃烧物对探测器响应随镂空比变化的规律无影响;格栅安装高度和格栅厚度不影响格栅吊顶上下方探测器响应顺序随镂空比的变化规律.     

Transport Time Lag Effect on Smoke Flow Characteristics in Long-Narrow Spaces

This paper focuses on the smoke transport lag time at the early stage of fires in long-narrow spaces, which is defined as the time from fire onset to the time when smoke reaches a given position on the ceiling. For a heat detector at a specific location on the ceiling, the smoke transport lag time is a part of the response time of the heat detector. Especially when the heat release rate is relatively small at the early stage of fires, the smoke transport lag time will be very long, which will hence lead to the increase of heat detector response time. It is clear that the prediction of smoke transport lag time is critical to the activation time of the heat detector. However, previous studies have much focused on fire characteristics in long-narrow spaces, leaving very few on the transport time lag. Therefore, in this study, a theoretical model regarding smoke transport time lag was developed for both steady and time-dependent fires based on the weak-plume theory. This model was validated by a series of reduced-scale experiments. It can be concluded from comparison that the predictions of this model agree reasonably well with the corresponding experimental results. Using the proposed method, the dimensionless equations of smoke transport time lag, velocity and temperature considering the smoke lag effect in a long-narrow space for time-squared fires were also theoretically deduced. Additionally, to further determine the applicability of ‘Quasi-steady’ state assumption for time-squared fires, a calculation method regarding the critical time was also developed. The outcomes from this study will be beneficial to the development of fire detection model in long-narrow spaces.     

火灾报警系统中家用可燃气体探测器的选型及使用

本文主要介绍对于应用于火灾报警系统中的点型家用可燃气体探测器种类,如何选型及使用中注意事项。     

水平交叉隧道间夹角对火灾烟气特征参数分布的影响研究

利用FDS数值模拟,研究火源位于支路隧道时,交叉隧道间夹角对主隧道内烟气蔓延的影响,分析了主隧道的烟气浓度、烟气层高度和顶棚最高温度分布状况。结果表明,随着角度由90°减小至30°,主隧道交叉口两侧的烟气浓度呈现非对称特点,钝角方向的烟气浓度大于锐角方向的烟气浓度,但是交叉角度对两个方向的烟气层高度的影响不明显。主隧道内钝角方向顶棚下方烟气最高温度大于锐角方向最高温度,钝角方向最高温度随夹角的减小而增大,锐角方向最高温度随夹角的减小而减小。基于烟气蔓延过程的质量和动量守恒分析,揭示了主隧道内烟气浓度、顶棚最高温度等特征参数的演化机制。