Heat strain in chemical protective clothing in hot-humid environment:Effects of clothing thermal properties

Heat strain experienced by individuals wearing chemical protective clothing(CPC)is severe and dangerous especially in hot-humid environment.The development of material science and interdisciplinary studies including ergonomics,physiology and heat transfer is urgently required for the reduction of heat strain.The aim of this paper was to study the relationship among clothing thermal properties,physiological responses and environmental conditions.Three kinds of CPC were selected.Eight participants wore CPC and walked(4 km/h,two slopes with 5%and 10%)on a treadmill in an environment with(35±0.5)℃ and RH of(60±5)%.Core temperature,mean skin temperature,heart rate,heat storage and tolerance time were recorded and analyzed.Physiological responses were significantly affected by the clothing thermal properties and activity intensity in hot-humid environment.The obtained results can help further development of heat strain model.New materials with lower evaporative resistance and less weight are necessary to release the heat strain in hot-humid environments.

Numerical Estimation of the Thermal Response of Thermal Protective Clothing-Air Gap-Human Skin Micro-system

Thermal protective clothing has been recognized as the primary shielding against emergency fire hazard and inflammable gas leakage. Therefore,the thermal response of human covered with thermal protective clothing under high temperature is the key work to investigate the thermal insulation of thermal protective clothing. A coupling model composed of thermal protective clothing,air gap and human skin is established and the temperature of the micro-system is numerically solved via the finite element method( FEM).Especially,the heat transfer of air gap located between clothing and human skin considering conduction and radiation is established while the human skin layers involve the effect of blood perfusion. Then the effect of thermophysical properties( thermal conductivity and volumetric capacity) of fabric and thickness of fabric and air on the thermal response of the micro-system is elucidated and compared.The results indicate that the volumetric heat capacity of fabric is the key parameter to affect the thermal shielding performance of thermal protective clothing,and the thicker fabric thickness and air gap thickness can improve the thermal protective properties of the micro-system.

Effect of Phase Change Materials on the Thermal Protective Performance of the Multi-layered Fabrics Examined by TPP Tester under Flash Fire

Cotton fabrics treated with phase change materials( PCMs)were used in multi-layered fabrics of the fire fighter protective clothing to study its effect on thermal protection. The thermal protective performance( TPP) of the multi-layered fabrics was measured by a TPP tester under flash fire. Results showed that the utilization of the PCM fabrics improved the thermal protective performance of the multi-layered fabrics. The fabric with a PCM add on of 41. 9% increased the thermal protection by 50. 6% and reduced the time to reach a second degree burn by 8. 4 s compared with the reference fabrics( without PCMs). The employment of the PCM fabrics also reduced the blackened areas on the inner layers. The PCM fabrics with higher PCM melting temperature could bring higher thermal protective performance.

Effect of Air Gap under Fabric on Thermal Protective Performance Using an Improved Apparatus

The bench top test is one of the most important and effective methods to evaluate the total thermal protective performance(TPP) of firefighters' protective clothing,which is greatly influenced by the air gaps entrapped.In this paper,to investigate the effect of air gap width on TPP,a new improved apparatus with two height changeable buttons to hold the thermal sensor was developed to get a series of air gap sizes from 0 mm to 40 mm.The TPP of two types of flame-resistant outer fabrics was measured with TPP test apparatus respectively.Analysis of temperature rise with each air gap width was made to determine the effects of different air gaps on protective performance.It was indicated that air gap size had great effect on TPP of fabrics in the bench top test.An air gap width above 8 mm was suggested for the thermal protective clothing design.

Modeling Thermal Protective Performance of Multilayer Fabrics for Firefighters

This paper is to report a prediction model for thermal protective performance of multilayer fabrics based on Matlab neural network toolbox. Then a back propagation (BP) neural network model is developed to predict thermal protective performance of multilayer fabrics for firefighters. The network consists of twelve input nodes, six hidden nodes, and one output node. The inputs are weight, thickness, density of warp and weft, limited oxygen index (LOI), and heat conductivity of each-layer fabric. Thermal protective performance (TPP) rating of multilayer fabrics is the output. In this paper, the data from the experiments are used as learning information for the neural network to develop a reliable prediction model. Finnally the model performance is verified, and the proposed model can be applied to predict the thermal protective performance of multilayer fabrics for firefighters.

Protective Performance of Woven Fabrics against Heat Radiation

In this paper,the protective performance of woven fab-rics against heat radiation is studied from the view offabric structure.As indices reflecting the protective per-formance against heat radiation,the heat emissivity andthe transmissivity of different fabrics are measured.It ispointed out that structure changes of common textiles af-fect their transmission to heat radiation while have littleinfluence on their absorption or reflection to heat radi-ation except fabrics surfaces are aluminized.Double-layer weave is proved to be an effective fabric weave forreducing the trasmissivity.It helps increase the densityand tightness while keeps the comfort of woven fabrics atthe same time.

Superabsorbent Fibers for Comfortable Disposable Medical Protective Clothing

Disposable medical protective clothing for 2019-nCoV mainly consists of stacked layers with nanopore films,polymer coated nonwoven fabrics and melt-blown nonwoven fabrics against anti-microbial and anti-liquid penetration.However,such structures lack moisture permeability and breathability leading to an uncomfortable,stuffy wearing experience.Here,we propose a novel medical protective clothing material with a superabsorbent layer to enhance moisture absorption.Poly(acrylic acid-co-acrylamide)/polyvinyl alcohol superabsorbent fibers(PAAAM/PVA fibers)were prepared via wet spinning.And the superabsorbent composite layer was stacked from PAAAM/PVA fibers,bamboo pulp fibers(BPF)and ethylene-propyl-ene side by side fibers(ESF).The novel disposable medical protective composite fabric was obtained through gluing the superabsorbent layer to the inner surface of strong antistatic polypropylene nonwoven fabric.The resultant composite fabric possesses excellent absorption and retention capacity for sweat,up to 12.3 g/g and 63.8%,and a maximum hygroscopic rate of 1.04 g/h,higher than that of the conventional material(only 0.53 g/h).The moisture permeability of the novel material reached 12,638.5 g/(m^(2) d),which was 307.6%of the conventional material.The novel material can effectively reduce the humidity inside the protective clothing and significantly improve the comfort of medical staff.

灭火防护服3层组合试样的热防护性能

消防员灭火防护服多为外层、防水透气层、舒适层3层织物制作,3层组合试样的质量和防护服质量直接相关。为了增强3层组合试样的热防护性能,实现灭火防护服轻量化,提高灭火救援的效率,试织了芳纶双层织物和玄武岩/阻燃粘胶包覆织物,试制了芳纶双层包覆聚四氟乙烯(PTFE)膜织物。选择2种舒适层织物和1种轻量防水透气层材料,制成不同组合试样并进行热防护性能测试。试验结果表明:3层组合试样经热防护性能测试后,玄武岩/阻燃粘胶包覆织物组织基本完整,防水透气层的PTFE膜炭化、损毁,防水性能缺失;芳纶双层织物做外层,芳纶混纺凹凸织物为舒适层的组合试样TPP值达1495.2 kW·s/m^(2),试样厚度大于3 mm。

高等级化学防护服用多层膜面料的阻燃性能和热防护性能

以芳纶织物、聚酯织物和腈纶织物为骨架层,聚烯烃膜为成型层,聚卤代烯烃膜为阻隔层,试制高等级化学防护服用多层膜面料。采用电子织物强力机、极限氧指数仪、锥形量热仪和热防护性能测试仪,研究织物种类及聚烯烃母粒和阻燃剂种类对多层膜面料力学性能、阻燃性能、燃烧行为和热防护性能的影响。结果表明:以芳纶织物和聚酯织物为骨架层的多层膜面料具有更好的力学性能;以B/C型聚烯烃母粒和Y型阻燃剂为原料的多层膜面料具有更高的阻燃性能;以腈纶织物为骨架层的多层膜面料具有更低的热释放和较高的残炭含量,但是由于在测试过程中会出现严重熔融现象,其热防护性能较差。综上,以芳纶织物为骨架层,C型母粒和Y型阻燃剂制备的聚烯烃膜为成型层,试制的多层膜面料综合性能最佳。

消防员灭火防护服减层结构及其热防护性能评价

介绍了消防员灭火防护服减层结构的实现方式,运用国内外不同的热防护性能评价方法,对标准4层组合面料及3层、2层减层结构组合面料进行评价,并采用热人仪测试不同组合面料制成的灭火防护服的防护效果。结果表明,3层和2层减层结构组合面料能达到标准4层组合面料的性能,满足消防员灭火防护服要求,符合轻质化发展趋势。

电弧能量对电弧热防护性能值测试结果的影响

探讨设置不同的电弧能量对电弧热防护性能值(ATPV)测试结果的影响。介绍了ATPV测试方法,包括测试设备、试样制备及预处理、测试程序和ATPV的确定方法。通过增加或减少电弧持续时间来改变电弧能量大小,共计进行了3组63份试样的测试。结果表明:当电弧时间集中在120 ms时,最终得到的ATPV最低;电弧时间集中在160 ms时,最终得到的ATPV最高;当电弧时间覆盖120 ms~180 ms时,得到的ATPV居中,且与真实值最接近。认为:在满足标准数据点分布要求的前提下,应尽可能在不同电弧能量水平下进行测试,以保证测试数据的准确性。

防熔融金属飞溅织物的防护机理及影响因素探讨

探究防熔融金属飞溅织物的防护机理,并对其影响因素进行试验分析。通过对熔融金属的特性以及织物在熔融金属作用下力学作用与热传递作用的分析,揭示了熔融金属飞溅的防护机理。测试了不同织物的抗熔融金属冲击性,从纤维原料和织物组织两方面进行了相关分析。试验结果表明:纤维种类是影响织物抗熔融金属冲击性的主要因素,其次是织物组织;织物紧度越大、组织系数越小,织物的抗熔融金属冲击性越好;织物厚度的影响不明显。认为:防熔融金属飞溅性能的关键在于实现面料的滑脱性与隔热性;从纤维配伍、织物紧度与组织结构三方面综合考虑,可提升面料的滑脱性,从而实现高等级熔融金属飞溅防护服的开发。

民用防火服装的研究现状分析及改良设计

随着社会对个人安全的日益重视,民用防火服装作为保护人们免受火灾伤害的重要装备,其研究和应用逐步受到重视。针对目前民用防火服装的研究仍存在集中于面料研发,忽视服装结构合理性而造成的防护性欠佳的问题,通过对前人研究成果的总结与分析,基于人体工程学,设计了一款适于应急火灾逃生的防火逃生服装,对比灭火毯、逃生斗篷等现有产品的防护性能,其可为未来更高性能防火服装的设计提供一定的参考。

高温防护服的舒适工效性能评价与优化对策

目前对于防护服的开发往往偏重功能性而忽视舒适性,舒适性不佳最终会影响穿着者的工作效率.针对国内工业中普遍应用的3类高温防护服,进行穿脱便捷性、工效学和穿着生理负荷测试,从受试者的穿着反馈探寻防护服对人体造成灵活性限制以及生理负荷的原因,结果表明,影响舒适工效性能的主要原因是关键部位结构不合理和材料厚重.根据防护服装的功能设计模式对测试的高温防护服提出结构设计优化策略,以达到改善服装舒适性、降低工作人员生理负荷、提高工作效率的目的,实现防护服的功能性和舒适性的相对平衡.

常用高、低温防护服隔热性能研究

为评价常用类型高、低温防护服的防护性能,本研究应用热平板仪、人工气候室和暖体假人等研究设备,对高低温作业典型工种常用的耐高温防护服和低温防护服的隔热性能进行了研究。研究结果显示,不同类型高、低温防护服的服装面料、服装整体的隔热性表现出一定差异,模拟环境下的着装生理学测试结果也存在不同,防护服的面料、结构和工艺等均影响到其整体隔热性能。防护服装的全面评价通常涉及安全性、工效学特性等多个方面,有必要从服装的舒适性、工效学特性等方面进一步研究,并开展大规模的现场人体穿着实验,从而为高低温防护服的选用和设计改进等提供依据。

热辐射暴露下消防员的生理反应及皮肤烧伤预测

为优化消防服热防护性能的评价准则,基于消防服热传递规律与人体热生理调节机制,建立了消防员生理反应与皮肤烧伤预测模型,利用服装热防护性能测试平台对比分析了平均皮肤温度、核心温度的变化趋势与预测误差。结果表明:基于模型预测的平均皮肤温度与核心温度均略大于实验测量结果,但总体变化趋势与实验结果具有较高的一致性;在热暴露条件下消防员面临着皮肤烧伤与热应激的双重威胁,皮肤烧伤更多发生在热暴露阶段,热应激更可能产生在热暴露结束之后,这是由于热传递的滞后效应导致;消防服热防护性能的评价需要综合考虑皮肤烧伤与人体热应激作为评价指标,从而更加准确地标定及优化消防服的热防护性能。

医用防护服用非织造布的热湿舒适性能研究

测试了医用防护服用非织造布的结构特征参数,热湿舒适性方面的透湿透气性,以及KES测试的低负荷下各项力学性能等各项性能。分析了非织造布相较于传统医用服装机织面料在热湿舒适性、触觉舒适性及成型性等方面的特点。通过所设计的实验装置用DL-700C红外热像仪监测了模拟衣下微气候的热湿传递特性,以及不同状态时面料表面温度的变化规律。提出了织物表面温度变化率作为表征非织造布的热湿舒适性能的评价指标。

火灾环境下应急救援防护服传热数值模拟

通过建立穿着于模拟人体的应急救援防护织物传热模型,研究模拟火灾环境下的服装传热特征。模拟人体肢体的圆柱体内核保持恒定温度37℃,模型考虑了织物吸收热辐射及热属性随温度变化的特性,运用有限差分完全隐式格式方法模拟计算织物与人体皮肤的一维径向温度分布,将计算得到的温度值代入Henriques烧伤模型方程以预测皮肤达到二级烧伤所需的时间,其值与实验结果较为一致。研究结果表明,圆柱几何形状对天然阻燃高聚物纤维织物的热防护性能影响效果较为显著,所建立的模型为覆盖于圆柱体的多孔材料传热提供了系统的研究方法。

智能发热户外防寒服装研制与性能评价

服装的构成方式会对其防寒性能产生影响。根据户外冷环境的防护要求,研制了新型的多层户外防寒服套装,包括防水外套、抓绒内胆、防寒裤,采用智能电加热装置提高户外防寒服装的调温性能。通过暖体假人试验和真人试验分别评价防寒服装在两种状态下(加热和不加热)的保暖性能。暖体假人试验还探讨了两种风速(0.4和1.5m/s)对户外防寒服的冷防护性能的影响,结合真人试验表征的皮肤温度变化以及主观感受,从而评价所研制的智能发热户外服装的防寒性能。研究结果将为优化户外防寒服的设计提供科学依据。

燃烧假人在火场热防护服装研究中的应用

热防护性是个体防护服装的重要功能。燃烧假人作为国际公认的定量评估防护装备阻燃性能的专用设备,在服装热防护研究中发挥着重要作用。通过对国内外相关研究成果的回顾,介绍了燃烧假人的热防护测评原理、发展历史及我国首个具有国际领先水平的燃烧假人—"东华火人"的创新特征,重点从不同火场状况的模拟、阻燃面料的评测与选择、服装款式结构对防护性能的影响以及阻燃防护服热传递机制研究等4个方面探讨了燃烧假人在服装热防护研究领域中的应用进展,最后对燃烧假人的应用前景进行了预测分析。