Experimental investigation on extinguishing performance of a novel nanocomposite for gaseous fires

A novel nanocomposite was synthesized by incorporating three different types of flame-retardants and its extinguishing performance was tested for gaseous fires. The nanocomposite consists of the inorganic magnesium hydroxide (MH) nanoparticles as the dominant component, the nitrogen-based melamine cyanurate (MCA), and the phosphorus-based ODOPB. The wet mixing, dry mixing, and ultrasonic agitation were employed in the preparation process to enhance the homogeneity of the nanocomposite. The prepared powders were characterized using a series of analytical instruments including X-ray diffraction (XRD), scanning electron microscopy (SEM), thermal gravity analyzer (TGA), and differential scanning calorimeter (DSC). The efficiency of various samples in extinguishing gaseous fires was investigated in a lab-scale extinguishing system. The fire extinguishing tests indicated that the nanocomposite is considerably more effective in fire extinguishing than other powders in terms of extinction time and agent mass consumed. The fire extinction time of nanocomposite was 45.2% shorter than that of commercial ABC-MAP powder. Furthermore, the consumed amount of nanocomposite was 63.2% less than that of commercial powder. In addition, the order of extinguishing mass concentrations was as follows: the novel nanocomposite (103.7 g/m³) < MH/MCA (148.1 g/m³) < MH/ODOPB (155.6 g/m³) < MH (170.4 g/m³) < commercial ABC powder (281.5 g/m³) < MCA/ODOPB (384.1 g/m³). The fire suppression mechanisms of the nanocomposite were also discussed. It was inferred that the extinguishing mechanism of nanocomposite comprised of simultaneous chemical and physical inhibition actions involving chemical inhibition action, cooling action, and asphyxiation action. This study provides a promising attempt to gain benefits from the striking features of nanotechnology and flame-retardants in extinguishing gaseous fires.     

The evolution of flame length for the oil tank fire with different top cover widths and lip heights

This study presents a quantitative analysis and interpretation of the variation in oil tank fire flame lengths for different oil tank sizes, top cover widths, and horizontal air flow velocities. The experimental results show that, at first, the flame length rises slowly with an increase in air flow speed. Then, once over a critical speed (0.6 m/s), the flame length decreases significantly with a further increase in air flow speed. Based on the characteristic length, a new dimensionless heat release rate is obtained, allowing the correlation between flame length, air flow speed, and dimensionless heat release rate to be calculated, which can be used to predict the flame length of an oil tank fire under different air flow speeds, lip heights, and cover widths.     

燃烧假人测试系统及其应用前景

燃烧假人测试系统是国际公认的定量评估防护装备阻燃性能的专用设备，本文主要介绍了燃烧假人测试系统的研究现状、系统构成、技术体系及应用前景。     

气相色谱——火焰光度法测定废水中黄磷的方法研究

研究了以苯为萃取剂，用气相色谱－－火焰光度法测定废水中的微量黄磷。结果色谱分离良好，萃取率大于９４％，水样易于保存，溶剂和杂质不干扰测定，水样加标回收率大于８８．４８％，精密度重复测定的变异系数不大于３．２％，定性检出限为２μｇ／Ｌ，定性检出限为６μｇ／Ｌ。     

地表水中痕量金属元素的原子吸收法测定

采用单缝石英管技术作为火焰原子化器的原子捕集阱,以火焰法测定地表水中Cu、Pb、Zn、Cd等痕量元素,进一步提高了石英管法的灵敏度。依上述元素的顺序,其方法的最低检出浓度分别为4.0、10.0、1.0、1.0μg·l~(-1);对不同浓度标准溶液的精密度实验,其变异系数分别为0.5％、0.6％、1.6％、0.4％;对地表水加标回收率试验结果分别为95％—106％、100％—105％、95％—109％、84％—99％。     

灰化-火焰原子吸收法测定人发中的金属元素

讨论了人发中元素测定的前处理条件，并采用灰化－火焰原子吸收法测定了人发中锌，铜，铁，钙和镁５种金属元素的含量。     

化学镀锡添加剂对镀层厚度及表面形貌的影响

采用电化学等方法研究了硫酸镍和水合肼对化学镀锡层厚度及表面形貌的影响.结果表明,硫酸镍起到了细化镀层的作用.而水合阱的加入使镀锡层的厚度增加.     

PBDF and PBDD from the combustion of bromine containing flame retarded polymers: A survey

The formation of polybrominated dibenzofurans (PBDF) and dibenzodioxins (PBDD) during the pyrolysis of different polymers containing brominated organic flame retardants was investigated. The pyrolyses were conducted at two different temperatures (600°C and 800°C) using three different oven configurations. Both the pyrolysis gases and the solid residues were analysed for PBDF and PBDD.

PBDF were found in almost all samples, but both the concentration and the degree of bromination varied greatly. The largest yields of PBDF in the percent range were measured in the pyrolysis products of polymers containing brominated diphenyl ethers. The other flame retardants generally yielded only a few ppm of PBDF. PBDD are formed only in a few samples and related to the PBDF in very low concentrations.     

交联壳聚糖富集分离火焰原子吸收法测定环境样品中微量锰

提出了交联壳聚糖 (CCTS)分离富集火焰原子吸收法测定环境样品中微量锰的新方法。研究了富集的最佳条件及洗脱方法 ;考察了共存元素的影响。方法的检出限为 2 .6μg/L ,RSD为 2 .9% ,用于牡蛎和人发标样中微量锰的测定 ,结果满意。     

Monitoring the levels of brominated and organophosphate flame retardants in passenger cars: Utilisation of car air filters as active samplers

Filters in residential and office air conditioning(A/C) systems have been used as sampling devices for monitoring different pollutants.However,cabin air filters(CAFs) in the A/C system of passenger cars have not been utilised for this purpose.In this study,we collected22 used CAFs from passenger cars in Hanoi,Vietnam to analyse for 8 polybrominated diphenyl ethers(PBDEs) and 10 organophosphate esters(OPEs).All the analytes were detected in more than 50% of samples with the exception of BDE153 and BDE154.The average concentrations of ∑_(10)OPEs and ∑_8 BDEs in the captured dust were 2600 and 40 ng/g,respectively with Tris(1-chloro-2-propyl) phosphate(TCIPP) and BDE209 as the dominant congener in OPE and BDE groups,respectively.CAFs are a potential tool to qualitatively assess the levels of semi-volatile chemicals in suspended dust in cars as a screening step for exposure assessment of those chemicals.