Protecting fire fighters exposed in room fires: Comparison of results of bench scale test for thermal protection and conditions during room flashover

Heat flux conditions measured in seven room fires are discussed. The conditions varied from just below flashover in a sparsely furnished bedroom to flashover and severe postflashover fire in a typically furnished recreation room. These heat flux conditions are compared with the protection level provided by fire fighter turnout coats conforming to NFPA 1971,Protective Clothing for Structural Fire Fighting. This standard requires that the turnout coat or pants assembly must protect the wearer against second degree burns when a heat flux of 84 kW/m² (2 cal/cm².s) is applied to its outside surface for a minimum of 17.5 seconds [thermal protective performance (TPP) of 35]. The results imply that fire fighters have only ten seconds or less to escape under most flashover conditions. However, the turnout coats provide good protection in many other fire situations. Practical definitions for flashover are given, and possible means for making the TPP test more relevant for research and development work are discussed.     

Heat Transfer in Thin Fibrous Materials Under High Heat Flux

A heat-transfer model has been developed for two common, inherently flame-resistant fabrics, Nomex® IIIA and Kevlar®/PBI, when subjected to the high heat fluxes used in bench top tests, such as the thermal protective performance (TPP) test, ASTM D 4108. The apparent heat capacity method was used to model thermochemical reactions in these materials with information from thermal gravimetric analysis (TGA) and differential scanning calorimeter (DSC) tests. Also included were in-depth radiation absorption, variable thermal properties, and heat transfer across an air space from the fabric to a test sensor. The finite element method was used to solve the resulting equations. Absolute temperatures predicted by this relatively simple model fall within 4% of those measured by an infrared thermometer. Estimated times to the Stoll second-degree burn criterion are within 6% of those derived from actual tests.     

A Heat Transfer Model for Firefighters' Protective Clothing

An accurate and flexible model of heat transfer through firefighter protective clothing has many uses, including investigating the degree of protection, in terms of burn injury and heat stress, of a particular fabric assembly and analyzing cheaply and quickly the expected performance of new or candidate fabric designs or fabric combinations.This paper presents the first stage in developing a heat transfer model for firefighters' protective clothing. The protective fabrics are assumed to be dry, which means no moisture from perspiration, and the fabric temperatures considered are below the point of thermal degradation, such as melting or charring. Many firefighter burns occur even when there is no thermal degradation of their protective gear. A planar geometry of the fabric layers is assumed with one-dimensional heat transfer. The forward-reverse model is used for radiative heat transfer. The accuracy of the model is tested by comparing time-dependent temperatures from both within and on the surface of a typical fabric assembly to those obtained experimentally. Overall, the model performed well, especially inside the garment where the temperature difference between the experiment and the stimulation was within 5°C. The predicted temperature on the outer shell of the garment differed most from experimental values, by much as 24°C. This was probably due to the absence of fabric-specific optical properties, such as transmissivity and reflectivity, used for model input.     

The Effects of Dyeing and Finishing Pretreatment Process to the Sliver Fiber Shielding Fabric and the Reasons

Through the silver fiber and cotton mixed silver fiber shielding fabric,not only soft and comfortable,it can wear personal,but also has excellent anti electromagnetic shielding effect. Fabric in dyeing and finishing process,may cause some damage on the silver fiber,influence the shielding performance of shielding fabric. Therefore,in this paper,through the experimental and analysis,find dyeing and finishing process may affect silver fiber shielding fabric and the reasons.     

主筋编排对织物增强水泥砂浆力学性能的影响

模拟钢筋混凝土配筋方式,用纤维增强砂浆筋代替传统钢筋增强水泥砂浆.采用玻璃纤维编制纤维增强砂浆筋作为主筋,用芳纶纤维对其进行横向连接并织成平面织物,然后用水泥浆进行固化.接着就主筋编排方式对织物增强水泥砂浆力学性能的影响进行研究.结果表明:辫子状主筋织物增强水泥砂浆的抗折、抗压强度比交织状主筋织物增强水泥砂浆的大;在宽度和厚度方向上的主筋根数有一个最佳值,高于或低于此值,其增强效果都会下降;较细主筋的增强效果比较粗主筋的好.     

Mechanisms of Fabric Reinforcement of Cement Matrices

The present paper discusses the mechanisms involve in fabric‐cement composites focusing on the effects of fabric geometry and the properties of the yarns. It was found that the geometry of a given fabric could enhance the bonding and enable one to obtain strain hardening behavior from low modulus yarn fabrics, due to the special shape of the yarn induced by the fabric. On the other hand, variations of the geometry in a fabric could drastically reduce the efficiency, resulting in a lower strengthening effect of the yarns in the fabric, relative to single yarns not in a fabric form. Therefore, in cement composites the fabrics can not be viewed simply as a means for holding together continuous yarns to be readily placed in the matrix, as is the case in composites with polymer matrix.     

Numerical Modeling of Heat and Moisture Through Wet Cotton Fabric Using the Method of Chemical Thermodynamic Law Under Simulated Fire

The paper deals with numerical modeling of heat and moisture transfer behavior of a fabric slab during combined drying and pyrolysis. The model incorporates the heat-induced changes in fabric thermo physical properties and the drying process is described by a one-step chemical reaction in the model. The new model has been validated by experimental data from modified Radiant Protective Performance (RPP) tests of fabrics. Comparisons with experimental data show that the predictions of mass loss rates, temperature profiles within the charring material and skin simulant, and the required time to 2nd skin burn are in reasonably good agreement with the experiments. It is concluded that moisture increases the time to 2nd degree skin burn for fabrics exposed to low intensity heat flux of 21 kW/m², but under high heat flux exposures, such as 42 kW/m², moisture tend to increase heat transfer through the thermal protective fabric system and the tolerance time of the same fabrics will reduce. The model can find applications not only in thermal protective clothing design, but also in other scientific and engineering fields involving heat transfer in porous media.     

纤维织物增强混凝土梁抗弯性能的试验研究

从试件抗弯性能测试、抗弯韧性指数计算，抗折强度的计算等，探讨了碳纤维格栅、碳／玻璃混杂纤维格栅织物增强混凝土复合材料的抗弯试验，经研究表明，纤维格栅织物可以明显提高混凝土的弯曲韧性指数和抗弯强度。     

织物增强混凝土的纤维协同等代效应对约束混凝土的影响分析

通过ABAQUS对织物增强混凝土拉伸性能及其永久模壳加固混凝土柱的轴压性能进行了数值分析,在材料层面研究了短纤维掺量、纤维织物层数对水泥基复合材料(ECC)和超高性能混凝土(UHPC)拉伸性能的影响;在结构层面研究织物增强超高性能混凝土模壳对不同强度核心区混凝土的约束效率及纤维织物和短纤维间的替代关系.结果表明:织物合...     

工艺参数对多层织物热防护性能的影响

采用成膜法,突破传统工艺手段,将SiO₂气凝胶、相变材料与纺织材料有效结合,制备轻质高性能隔热薄膜,通过改变制备工艺中刮刀厚度、刮刀速度、无水乙醇与蒸馏水配比等直接影响薄膜厚度的工艺参数,得到不同厚度及性能参数的隔热薄膜,揭示相应薄膜所在多层织物二级烧伤时间的变化规律,获得工艺参数对消防服用材料热防护性能的影响。结果表明：随着刮膜厚度和刮刀速度的增加,二级烧伤时间先增加后降低;理论厚度为500 μm     

聚丙烯腈织物热稳定性与燃烧特性研究

对聚丙烯腈(PAN)织物在空气气氛下的热稳定性和3种热辐射强度下的燃烧特性进行研究。结果表明,PAN织物在空气气氛中的热分解过程主要包括3个失重阶段;随着热辐射强度的增大,PAN织物点燃时间有所提前,热释放速率和产烟率的峰值均得到了一定程度的提高,到达峰值的时间均有不同程度的提前,质量损失率增加,且初始热分解时间提前;当热辐射强度为25 kW/m2时,PAN织物的燃烧不充分,烟密度最大;热辐射强度越大,烟气扩散越快,且PAN织物的火灾性能指数值减小,火灾增长指数值增大;PAN织物具有较高的火灾危险性。     

Performance evaluation of fabrics used in fire fighters' turnout coats

Several fabrics commonly used in the outer shells of structural fire fighters' turnout coats were subjected to a variety of laboratory tests. These included breaking and tearing strength tests as well as several kinds of abrasion tests.     

Predicting Mechanical Strength of In-Use Firefighter Protective Clothing Using Near-Infrared Spectroscopy

The exact lifespan of in-use firefighter protective clothing is difficult to predict due to the large variations in use between individual garments. Furthermore, testing methods used to evaluate new protective clothing are destructive in nature and could not be applied to in-use garments. Various non-destructive techniques have been proposed for the evaluation of in-use clothing, each possessing its own advantages and disadvantages. The ability of near-infrared spectroscopy to predict the tensile strength of thermally aged fabrics used in protective clothing for wildland firefighters and other workers is investigated here. Fabrics were exposed to heat fluxes from 10 kW/m² to 40 kW/m² for various durations using the cone calorimeter, after which the tensile strength of the fabrics was measured. Temperatures measured during the exposures and results of thermal gravimetric analysis tests were used to interpret changes in tensile strength. Multivariate linear regression was used to develop correlations between the tensile strength and the reflectance values measured between 1500 nm and 2500 nm for new and thermally aged fabrics. It was found that models based on reflectance measurements made at as few as three wavelengths could be used to estimate the tensile strength of the thermally aged specimens.     

壳聚糖/海藻酸钠涂层及其阻燃涤纶织物研究

以生物基多糖衍生的壳聚糖（CS）和海藻酸钠(AL)为改性剂,通过静电作用力驱动的层层自组装技术在聚对苯二甲酸乙二酯（PET）纤维织物进行阻燃修饰。通过扫描电镜,证实了壳聚糖和海藻酸钠在PET 织物表面的自组装沉积。利用热重分析仪与锥形量热仪等考察了壳聚糖和海藻酸钠的用量对PET 织物的热稳定性阻燃及抑烟性能的影响,并通过炭渣形貌和热解产物分析了天然生物基多糖的阻燃机理。结果表明,将生物基多糖沉积到PET 织物表面能有效提高织物的热稳定性、阻燃和抑烟性能。热解产物与炭层结构分析发现,天然生物基多糖的沉积促进了致密炭层的形成,有效地保护了底部聚合物,同时抑制了热解过程,从而提升了阻燃性能。     

Dynamic tensile testing of fabric–cement composites

Dynamic tensile tests were conducted using a high speed servo-hydraulic testing machine on three types of fabric reinforced cement composites. The high speed testing procedure and data processing method are presented. Quasi-static tests were also conducted on the composites. Effects of strain rate on the mechanical properties of fabric–cement composites are noted. A good correlation was found between the properties of the fabrics and the composites, with the carbon fabric exhibiting the highest strength and ductility performance in high speed tensile tests. The differences in tensile behavior of the various composites were correlated with the differences in the role of the fabric materials. Composites tested under high speed loading exhibited different responses as compared to similar composites tested under quasi-static condition.     

Firefighter Turnout Gear Durability Study—Evaluation of Visibility Trim

The high visibility trim requirements for NFPA 1971 (2007 ed.) turnout gear are intended to provide the user conspicuity enhancements in both daytime and nighttime environments. This study evaluated the reflectance, color and fluorescence properties of high visibility trim on firefighters used turnout gear. Forty-four used garments, grouped in age categories from 2 to 10 years (retired), were visually evaluated according to the Section 4 of the NFPA 1851—Advanced Inspection Checklist. Advanced inspection identified damaged trim on 21 of the 46 garments. The damaged areas, located primarily at the cuffs and lower front hem, were not as reflective but passed the subjective flashlight test. A data sampling plan for retroreflective values was constructed for the coats and pants and the coefficients of retroreflection were collected to provide a measure of the nighttime conspicuity. To characterize the fluorescent (daytime) properties of the trim on the used garments the values for fluorescence and color box coordinates were measured. The measured coefficient of retroreflection (R_A, cd/lux/m²) for all garments (average of all values in the sampling plan) was greater than 3× the minimum NFPA 1851 requirement. Therefore, all used gear provided substantial nighttime conspicuity enhancement including the retired gear.     

典型汽车内饰材料的燃烧特性研究

采用锥形量热仪实验对涤纶面料丙纶玻璃纤维板、涤纶面料丙纶麻纤维板和 PVC 革丙纶麻纤维板 3 种典型汽车内饰材料在 25、35、50 kW/m2 热辐射强度下的点燃时间、质量损失率、热释放速率等燃烧特性参数进行研究,并选取点燃预测模型计算材料的临界热辐射强度,使用轰燃倾向指数和热释放总量评价其潜在火灾危险性。结果表明,在实验热辐射强度下,涤纶面料丙纶麻纤维板质量损失百分率最大,结构完整性最差;涤纶面料丙纶玻璃纤维板平均点燃时间最短,临界热辐射强度最小,最容易被引燃;PVC 革丙纶麻纤维板热释放速率峰值最大,火灾性能指数最小,发生轰燃的可能性最大。     

Ignition testing of fabrics and fabric/cushion systems

The ignition behavior of furniture upholstery fabrics appears to be influenced by fabric variables (weight, weave, construction, and backcoating), test conditions, and substrate as much as by the chemical composition of the fiber.     

带负离子功能滤料的直接蒸发冷却器的实验研究

为了进一步提高经过直接蒸发冷却器处理后的空气品质,本文提出将直接蒸发冷却和负离子技术相结合。通过实验测试了织物组织、纱线类别、织物纬密和空气相对湿度对织物的负离子释放量的影响。实验结果表明,蜂巢组织织物释放的负离子数量最大,平纹组织织物的负离子释放量最小;负离子功能涤棉混纺纱的负离子释放量多于负离子功能纤维粘胶长丝的负离子释放量;各种组织的织物释放负离子的数量均随着织物纬密的增加而减小;织物释放负离子数量随着湿度的增加而上升。     

路用纤维橡胶粉混凝土力学性能试验研究

为了研究纤维和橡胶粉协同作用对路用混凝土力学性能和延性的影响规律,通过了22组试验,分别对基准混凝土、橡胶混凝土和纤维橡胶混凝土进行了抗压强度、抗折强度和劈裂强度试验。试验结果表明:随着40目橡胶粉掺量的增加,混凝土抗压强度有降低的变化规律;纤维和橡胶粉的复配掺入,可以改善混凝土的抗折强度和延性,对于纤维-40目橡胶粉混凝土,橡胶粉掺量控制在6%以内,纤维掺量控制在0.5%以内为佳;有利于改善路用混凝土的使用性能,为路用纤维橡胶混凝土的利用提供借鉴。