Fire and Materials最新文献

Ceramification of polymer composites is an excellent method for enhancing the flame retardancy of the materials. The low temperature softening glass frit added in the composites plays a key role in the ceramification process of the composites. Ceramizable polyethylene (PE)/wollastonite fiber (WF) composites are processed by mixing with three types of glass frit. The ceramic residues formed were characterized by the linear shrinkage, weight loss, flexural strength, apparent porosity, and self-supporting property measurements. The density and strength of the ceramic increased with the increasing sintering temperature, but were affected by the wettability and fluidity of the glass frit. The addition of glass frit can increase the thermal decomposition temperature of PE. X-ray diffraction (XRD) analysis found the form of a new phase of hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂) in the ceramifiable PE/WF composites by adding phosphate glass frit, which improved the self-supporting properties of the ceramic residues.

Optical cable is an important part of modern telecommunications infrastructure. In this study, cone calorimeter experiments are conducted on the optical cables which are widely being applied in utility tunnels in China. The coupling effect of the spacing between optical cables (8, 10, 12, 15 mm) and the heat flux (30, 40, 50 kW/m²) on fire performance of optical cables is studied. It is highlighted that the optical cables conform to the ignition time model of the thermally thin material. The ignition time of the optical cables decreases when increasing the heat flux. When the heat flux is 30 kW/m², the ignition time of the optical cable with different spacing varies greatly. When the heat flux is greater than 30 kW/m², the difference in the ignition time between the optical cable samples with different spacing is small. Furthermore, the average mass loss rate of the optical cables increases when increasing either the heat flux or the spacing between optical cables. The heat release rate of the optical cables also increases when increasing either the heat flux or the spacing between optical cables. The curves of the heat release rate versus time show two peaks, the second one being significantly smaller.

This paper investigates the soot sheet characteristics of buoyant turbulent fires using laser-induced incandescence technique. Experiments are carried out for four fires using propane and nitrogen hybrid gases as fuel with propane fractions of 1.0–0.4. An equivalent ellipse method in previous literature was employed to evaluate soot sheet characteristics. The results show that soot sheet mainly exists in two kinds of morphology: one is small piece and the other is narrow and long piece. Both the probability density functions of the length and width of the equivalent ellipse and soot volume fraction of soot sheet are strongly dependent on height. In addition, the effect of propane fraction on the probability density functions is always opposite in the lower and middle part of the fires, while no obvious effect can be found in the upper part of the fires. Soot sheet number is found to increase with height except when propane fraction is 0.4. The total soot sheet number increases linearly with height within the scope of this paper.

Post-flashover fires inherently lead to external fire plumes, constituting a hazard for rapid fire spread over façades. As multi-storey mass timber buildings with internal visible timber surfaces become more common, there are concerns that such buildings would produce larger external plumes and hazards (assuming all other parameters equal). The literature reveals only indications of this, and how the actual exposure relates to different test methods for assessment is unknown. Here we utilise a series of full-scale mass timber compartment tests to quantify the exposure to the external façade. An incombustible external façade is instrumented with gauges at positions corresponding to reference data from several different assessment methods. The results show that there is an increase in plume duration, height, and temperatures when increasing the areas of exposed timber, but that this increase is less for normal- to large-opening compartments, than was previously seen in small-opening compartments. Also, normal variations in external wind speed have a larger influence on plume heights than the effect of doubling exposed timber surfaces. Test methods used for regulatory compliance differ significantly not only in exposure but also in pass/fail criteria. The proposed European large exposure method and the BS8414 method exhibit exposures on par with the severe end of what could be expected from mass timber compartments, whereas methods like SP Fire 105 and Lepir II produce significantly less severe plumes. However, the safety level is always a combination of exposure and assessment criteria. This data can help justify assessment criteria from a performance perspective.

The use of mass timber in construction is becoming a compelling option when faced with the high carbon footprint of traditional concrete and steel production. However, fire safety standards are yet to evolve to support these designs. Encapsulation is commonly used to protect all, or some, of the timber surfaces and reduce the risks introduced. This paper presents the results from CodeRed #04, the final experiment of the CodeRed experimental campaign. This experiment was carried out inside a purpose-built facility to capture fire dynamics in large compartments with exposed timber. CodeRed #04 had identical characteristics to CodeRed #01 with the exception that ~50% of the cross-laminated timber (CLT) ceiling was encapsulated. The experiments were intentionally similar to the traveling fire experiments, x-ONE and x-TWO, which had a non-combustible ceiling to enable a direct comparison. The overall fire dynamics experienced in CodeRed #04, intersect the characteristics observed in CodeRed #01 and x-ONE and x-TWO.1. In CodeRed #04, there was a delay in the ignition of the CLT ceiling as the CLT directly above the crib was encapsulated. Once the CLT ceiling ignited, the fire spread rapidly throughout the compartment. The peak heat release rate (HRR) was estimated to be approximately 100 MW, a 17% decrease from CodeRed #01. Following CLT ignition the resulting fire duration, maximum temperatures, and heat fluxes were broadly similar to CodeRed #01. Flame heights of approximately 1.5 m were observed from the windows while flame heights of 2.5–3 m were observed in CodeRed #01. Therefore, flame heights were found to be comparable to x-TWO.1, though over a greater number of windows, reflecting the greater extent of simultaneous burning within the compartment. The average charring depth of the exposed CLT panels was ~25 mm, which is similar to that measured in CodeRed #01-suggesting that the fire severity near the ceiling was not strongly impacted by the 50% encapsulation of timber. No charring was observed where the ceiling was encapsulated and loaded service fixings installed through the encapsulation were found to be less likely to fail than when attached directly to the exposed timber. Smoldering was observed after the cessation of flaming and, in a few locations, was observed to progress through the thickness of the CLT panel and continue behind the encapsulation. This illustrates that, while encapsulation can succcessfully prevent flaming, it cannot be completely relied on to avoid smouldering. The findings from CodeRed #04 contribute to the development of evidence-based fire safety design methodologies for exposed mass timber buildings.

A set of experimental equipment for quenching the deflagration flame in linked vessels with parallel narrow channels was proposed. The quenching effects of the deflagration flame in the linked vessels were investigated, the influence law and mechanism of parallel narrow channels on the deflagration flame was analyzed. The results showed that the P_max and the (dP/dt)_max at each position were both lower than without parallel narrow channels, which indicated that the propagation of flame was inhibited by parallel narrow channels effectively, and the explosion intensity was also reduced. The pressure oscillation phenomenon inside the linked vessels disappeared due to the inclusion of parallel narrow channels. The deflagration flame was successfully quenched when the channel gaps were 0.5, 1.5, and 3 mm, but failed to be quenched when the channel gap was 6 mm. The quenching distance and the average propagation velocity of the deflagration flame in parallel narrow channels increased with the increase of the channel gap. When the channel gap was 6 mm, the deflagration flame completely passed through parallel narrow channels, and the average propagation velocity of deflagration flame was significantly greater than that when the deflagration flame was successfully quenched.

Coal spontaneous combustion (CSC) has hindered the utilization of coal resources and the development of the global economy for centuries. At present, many materials are used for preventing and extinguishing CSC fires, and different types of materials have various sites of action. In this paper, research on CSC fire prevention and extinguishing materials is reviewed and proposed. The preparation schemes and effects of physical barrier materials, chemical inhibitors, composite materials, and other fields of fire prevention materials were discussed. The improved compounding schemes of CSC inhibiting materials were analyzed regarding the characteristics of base materials and material properties. It was found that in the field of fire prevention materials, plant extracts, hydrolyzed proteins, biomass, and other green recycling materials have gradually become the new trend in materials. The composite material has a synergistic physical barrier and chemical inhibition and has a good inhibitory effect on coal heat storage and group activation, which has become an inhibitory material that is highly concerning. CSC inhibiting technology involving microbial control has emerged and exhibits notable characteristics, including a green cycle and long action time, but its application still needs to control the coexistence of heterogeneous microorganisms and improve the environmental livability. High-quality firefighting materials, which are used in preventing battery fires, fighting building fires, inert coatings of cotton fabric, and other fields, have potential applicational value for CSC prevention. This review aims to provide new ideas for the research of CSC fireproof materials.

Firebrands, or smoldering and/or flaming particles, are in fact the main culprit to destroy structures in large outdoor fires. A recent comprehensive review of firebrand combustion reported that deposition and subsequent accumulation processes remain largely unexplored. As part of this work, a series of experiments were undertaken to investigate firebrand deposition and accumulation processes in the National Research Institute of Fire and Disaster (NRIFD)'s wind facility. A reduced-scale firebrand generator was utilized, and various flow obstructions were placed downstream of these firebrand generators to better understand these complex deposition processes. Results of these investigations for multiple wind speeds, firebrand size and mass distributions, and obstacle placement are presented and discussed.

The properties including combustibility, rigidity, thermal conductivity, and the color of the fiber sample influence the flammability characteristics of composite materials. Although the influence of phosphorus-based fire retardants on the flammability characteristics of glass fiber-based composite materials has been well studied, there is a need to better understand the effects of these fire retardants on the flammability characteristics of carbon fiber-based composites. In the current study, four different commercially available phosphorus compounds (melamine polyphosphate (MPP), 9, 10-dihydro-9-oxa-10-phosphaphenanthrene10-oxide (DOPO), aluminum diethyl phosphinate (AlPi), and zinc diethyl phosphinate (ZnPi)) are used. The flammability test results indicate that UL-94 V rating maintains to burn to clamp with the addition of MPP, DOPO, and ZnPi in all concentrations. The highest UL94 V rating of V0 is obtained with the addition 10 wt% AlPi. An increase in LOI value is observed in samples containing MPP, AlPi, and DOPO. The highest LOI value of 41.5% is observed with the addition of 20 wt% AlPi. According to the MLC results, the lower peak heat release rate (pHRR) and total heat evolved (THE) values are obtained with the addition of all studied phosphorus compounds. The lowest pHRR (157 ± 10 kW/m²) and THE (44 ± 5 MJ/m²) values are obtained with the use of 20 wt% MPP and DOPO, respectively. The highest fire performance index (FPI) is achieved with the use of AlPi. Apart from DOPO which shows its effect predominantly in the gas phase, the studied phosphorus compounds exert flame retardant action both in the condensed and gas phases.