Assessment of the fire toxicity of building insulation materials

A significant element in the cost of a new building is devoted to fire safety. Energy efficiency drives the replacement of traditional building materials with lightweight insulation materials, which, if flammable can contribute to the fire load. Most fire deaths arise from inhalation of toxic gases. The fire toxicity of six insulation materials (glass wool, stone wool, expanded polystyrene foam, phenolic foam, polyurethane foam and polyisocyanurate foam) was investigated under a range of fire conditions. Two of the materials, stone wool and glass wool failed to ignite and gave consistently low yields of all of the toxic products. The toxicities of the effluents, showing the contribution of individual toxic components, are compared using the fractional effective dose (FED) model and LC₅₀ (the mass required per unit volume to generate a lethal atmosphere under specified conditions). For polyisocyanurate and polyurethane foam this shows a significant contribution from hydrogen cyanide resulting in doubling of the overall toxicity, as the fire condition changes from well-ventilated to under-ventilated. These materials showed an order of increasing fire toxicity, from stone wool (least toxic), glass wool, polystyrene, phenolic, polyurethane to polyisocyanurate foam (most toxic).     

Experimental Study of the Fire Behaviour on Flat Roof Constructions with Multiple Photovoltaic (PV) Panels

Fire experiments were conducted on four mock-up roof constructions with an array of six photovoltaic (PV) panels to study the fire dynamics and flame spread behaviour, so as to better characterise the fire risks of such a system. As it is customary to retrofit PV panels to existing warehouse roofs, where expanded polystyrene (EPS) and polyvinylchloride-based roofing membrane B_ROOF(t2) is a typical roofing, the experiments were carried out on such installations, but with a mitigation solution on top; 30 mm mineral wool or 40 mm polyisocyanurate (PIR). All mock-ups were 6.0 m long, whereas the width was 2.4 m (Experiments 1 and 2) and 4.8 m (Experiments 3 and 4), respectively. A wood crib was placed under the PV panels and it ignited the roofing membrane after 7 min to 8 min, which in all four experiments resulted in fire spread under all the six PV panels covering an area of 5.1 m?×?2.0 m. However, no self-sustained fire was observed beyond the area below the PV array. Within the first hour, the maximum temperatures were measured to respectively 175 °C and 243 °C underneath the two mitigation solutions of PIR insulation and mineral wool, which is more than 100 °C below the piloted ignition temperature for the EPS insulation. However, the EPS was ignited in both experiments with the PIR insulation due to thermal degradation of the protective material after approximately 1 h. These experiments confirm that a small initial fire underneath a PV installation can transform into a hazardous scenario due to the changed fire dynamics associated with adding the PV panels to the existing roof.     

Experimental study on the influence of different thermal insulation materials on the fire dynamics in a reduced-scale enclosure

Four scaled (1:5) fire experiments with two identically classified types of commercially available sandwich panels incorporating either stone wool (SW) or polyisocyanurate (PIR) foam as cores were conducted using a modified version of the ISO 13784-1 (Reaction to fire tests for sandwich panel building systems — Part 1: Small room test) standard. This was to assess the suitability of scaled experiments for assessing sandwich panel fire behavior. In the modified version of the test standard (scaled and full experiments), the fire severity was increased to simulate fires that could occur in commercial premises. This was achieved by prolonging and doubling the heat release rate output of the gas burner at the end of the experiments. Furthermore, non-structural damages such as screw-hole damages were applied to the enclosures to reflect real life observations.The results showed differences in the fire behavior, depending on whether the enclosures were constructed of panels filled with SW or PIR insulation material. The mass losses of the insulation materials showed significant contribution from the PIR cores, regardless of fire load and the non-structural damage.The qualitative behavior with respect to the “flashover” failure criterion, as stated in the ISO 13784-1, was successfully obtained in all of the scaled experiments. As such, the scaled experiments mimicked the behavior of the full scale SW experiments to a satisfactory degree. However, the PIR compartments failed considerably earlier in the full scale tests than in the scaled experiments. Therefore, it can be concluded that when the energy contribution from the core material remained negligible compared to the gas burner, the measured parameters matched quite well. Therefore, if the insulating core material does not dominate the fire dynamics of the compartment and the energy from the gas burner dictates the fire scenario then the scaled set-up will predict the temperature in the full scale compartment. Based on this and with further development with respect to, especially, time, this kind of scaled experiments could be a valuable testing method for assessment of the behavior of sandwich panel, and therefore merit further studies and eventually increased use.     

The Effectiveness of Horizontal Barriers in Preventing Fire Spread on Vertical Insulation Panels Made of Polystyrene Foams

Expanded polystyrene (EPS) and extruded polystyrene (XPS) foams are both excellent exterior thermal insulation materials for buildings. However, their flammability also induces high fire hazard. Current regulation in China requires horizontal fire barriers with a minimum height of 30 cm when polystyrene foams are used as the external insulation. The present work evaluates the effectiveness of such barriers in inhibiting fire growth in insulation walls. The walls were made of B2 grade EPS and XPS foams without protective coatings but with mineral wool as horizontal barriers. Altogether six combinations of fire positions and barrier positions were tested for both EPS and XPS. The heat release rate (HRR) of the fire and the temperature distribution on the wall were recorded and analyzed. The results indicate that, without a barrier, fire starting at the middle of the wall generated higher peak HRR than that starting at the bottom, which was in turn higher than that starting at the top. When the insulation panel below the barrier was 1 m high, the upward fire spread from the bottom could be stopped by 40-cm, but not 30-cm, barriers. However, when the insulation panel below the barrier was 2 m high, even the 40-cm barriers failed. Lastly, the downward fire spread from above could not be stopped by 40-cm barrier due to dripping of burning plastics. The study highlights the limitations of horizontal fire barriers in preventing the vertical fire spread over exposed B2 grade polystyrene insulation and establishes protocols for further investigations.     

Variation of Intumescent Coatings Revealing Different Modes of Action for Good Protection Performance

Thermal insulation and mechanical resistance play a crucial role for the performance of an intumescent coating. Both properties depend strongly on the morphology and morphological development of the foamed residue. Small amounts (4 wt%) of fiberglass, clay and a copper salt, respectively, are incorporated into an intumescent coating to study their influence on the morphology and performance of the residues. The bench scale fire tests were performed on 75 × 75 × 2 mm³ coated steel plates according to the standard time–temperature curve in the Standard Time Temperature Muffle Furnace⁺ (STT Mufu⁺). It provided information about foaming dynamics (expansion rates) and thermal insulation. Adding the copper salt halved the expansion height, whereas the clay and fiberglass change the height of the residue only moderately. The time to reach 500°C was improved by 31% for clay and 15% for the other two fillers. Nondestructive micro computed tomography is used to assess the inner structure of the residues. A transition of the residue from a black, carbonaceous foam with closed cells into an inorganic, residual open cell sponge occurs at high temperatures. This transition is due to a loss of carbon; the change in microstructure is analyzed by scanning electron microscopy. Additional mechanical tests are performed and interpreted with respect to the results of the morphology analysis. Adding clay or copper salt improved the mechanical resistance tested by a factor 4. The additives significantly influence the thickness and foaming dynamics as well as the inner structure of the residues, whereas their influence on insulation performance is moderate. In conclusion, different modes of action are observed to achieve similar insulation performance during the fire test.     

Numerical Simulation of Fire Exposed Façades Using LEPIR II Testing Facility

The fire behavior of external wall insulation system on façades is assessed during LEPIR II testing. This facility involves a 600 kg wood crib fire in a 30 m³ lower compartment of a two levels high concrete structure. External flames develop in front of the façade from the fire compartment through windows with dimensions 1?×?1.5 m (W?×?H). In order to predict the fire exposure of a façade during the test, CFD simulations were carried out with the computational fluid dynamics code Fire Dynamics Simulator (FDS) for two full-scale experiments. The main objective of this study was to evaluate the ability of FDS to reproduce quantitative results in terms of gas temperatures and heat fluxes close to the tested façade. This is an important step before the fire performances of any insulation system can be predicted by numerical tools. A good repeatability was observed in terms of measured gas temperatures for experiments. Maximum heat release rate of the fire, close to 5 MW, was achieved after 5 min of test. When experimental results were compared with numerical calculations, good agreement was found for every quantity. The most critical zone on the facade is located above the fire room and is directly impacted by external flame outgoing from the fire compartment. Temperatures up to 500°C were observed in this zone. For the thermocouples located up to the second level opening, these probes were not located directly in the flames, but rather in the hot gases above the fire plume. The maximum temperature achieved was thus close to 400°C. The proposed model gives correct thermal loads and flames shape near the façade during calibration tests and can be used for further evaluation of combustible material on façade.     

A级防火等级外墙外保温系统推荐

针对国家发布的建筑保温材料性能要求,甄选了国内的4种A级防火外保温系统:STP超薄绝热保温板外墙外保温系统、发泡陶瓷板外墙外保温系统、玻化微珠无机保温砂浆外墙外保温系统和岩棉板薄抹灰外墙外保温系统,分析了4种外保温系统的利弊,提出了各个系统使用的注意点,并提供了工程选用的推荐方案.     

Effect of temperature on thermal properties of spray applied fire resistive materials

Thermal properties of fire insulation namely thermal conductivity, specific heat, thermal strain and mass loss play a critical role in determining the effectiveness of these materials to improve fire resistance of steel structural members. These properties vary with temperature and are predominantly governed by moisture content and chemical constituents. This paper presents the effect of temperature on thermal properties of different types of spray applied fire resistive materials (SFRM). High temperature property tests were carried out on three types of commercially available SFRM to measure thermal conductivity, specific heat, mass loss and thermal strain in the range of 20–1000 °C. Data from these tests show that temperature has significant influence on thermal conductivity, thermal expansion and mass loss of fire insulation. The measured test data are utilized to develop thermal property relationships for fire insulation in terms of temperature. The proposed relations can be used as input data in thermo-mechanical analysis for evaluating fire resistance of steel structures.     

钢结构围护-防火一体化材料耐火性能试验研究

根据钢结构防火保护材料的相关技术要求,通过对常见的钢结构围护材料进行评价,筛选了包括水泥基材料中的无机轻集料砂浆、胶粉聚苯颗粒、蒸压轻质加气混凝土(autoclaved lightweight concrete,ALC),保温浆料中的石膏基保温浆料、微孔硅酸钙浆料,以及保温板材中的发泡陶瓷保温板和岩棉板在内的3类可以兼...     

外墙保温用保温板关键性能调研

参考JG 149—2003规定对典型外保温板材分别进行了常规性能测试,并对岩棉板、玻璃棉板、矿棉板类无机板材进行了高温稳定性和碱稳定性测试。探讨了其作为防火隔离带材料的可行性。针对市面上涌现出的吸水率较大的保温板材,课题组选择岩棉板、玻璃棉板、玻化微珠保温板、酚醛板作为研究对象,进行了不同含水率下的导热系数测试。拟通过试验结果真实反应当前保温板材的性能,给外墙保温板材的正确使用提供一定指导。     

Ignition,Heat Release Rate and Suppression of Elastomeric Materials

The focus of this paper is to determine flammability characteristics of rubber materials that are common to vehicle tires, conveyor belts, and electrical power cable insulation and to compare the thermal magnitude of cargo quantities of these materials to other fuels that are publicly transported. Although a literature review was performed, very little data was found on this topic. Standard flammability test procedures were used to measure the critical flux for ignition, critical ignition temperature, and heat release rates (HRR) of rubber compounds common to tire tread materials and conveyor belt covers. Both the intermediate scale calorimeter: ISO 14696, ASTM E-1623 (ICAL) and the cone calorimeter: ISO E-5660, ASTM 1354 (Cone) provided the bulk of the data. Critical ignition flux and vertical flame spread data for rubber based electrical insulations were determined using a radiant panel from a modified ASTM flame spread apparatus: ASTM E-162. thermogravimetric analysis was also used to evaluate thermal decomposition progression of selected test materials. Further, suppression tests were conducted on tire piles to evaluate agents to extinguish and control tire fires. Also, the HRR of the tire piles were measured and compared to work performed by others. Results confirm that the area heat release rate of rubber materials is directly proportional to exposure flux intensity. The critical exposure flux for ignition of a variety of rubber-based materials is approximately 20 kW/m² to 30 kW/m² and the critical temperature for piloted and non-piloted ignition were independent of exposure intensity at ~400°C and ~600°C respectively. In large quantities, rubber tire loads have total HRR comparable to the heat released from similar areas of liquid hydrocarbon spills.     

Fire Performance of Phase Change Material Enhanced Plasterboard

Sustainable construction materials are increasingly being used to reduce the carbon footprint of modern buildings. These materials have the potential to change the fire dynamics of compartments by altering the compartment energy balance however there is little quantitative understanding of how these materials behave in the event of a real fire. The changes in fire dynamics may be due to increased fuel load in a compartment, reduced time to failure or promotion of flame spread. The objective of this research is to quantify how Phase Change Materials (PCMs) perform in realistic fire scenarios. It was found that a plasterboard product containing microencapsulated PCMs will behave similarly to a charring solid and have the potential to contribute significant fuel to a compartment fire but that they maintain integrity for the duration of flaming period. The critical heat flux for this product was determined in the cone calorimeter to be 17.5 ± 2.5 kW m^?2, the peak heat release rate and mass loss rate ranged from 60.2 kW m^?2 to 107 kW m^?2 and 1.88 g s^?1 m^?2 to 8.47 g s^?1 m^?2 respectively for exposures between 20 kW m^?2 and 70 kW m^?2. Sample orientation was found to increase the peak heat release rate by up to 25%, whilst having little to no effect on the mass loss rate. These parameters, in addition to the in-depth temperature evolution and ignition properties, can be used as design criteria for balancing energy savings with quantified fire performance.     

含阻燃特性原子多元醇对硬质聚氨酯性能的影响

基于市场上现有的商业化原材料,通过改变硬质聚氨酯泡沫配方中多元醇的类型,寻找最佳阻燃性能的配方.选取常规高羟值聚酯多元醇A、常规低羟值聚酯多元醇B、含氮聚酯多元醇C、含溴和氯阻燃聚醚多元醇D、含溴阻燃聚醚多元醇E作为硬质聚氨酯泡沫配方中的多元醇组分,通过测定泡沫氧指数等阻燃性能,来研究多元醇对硬质聚氨酯泡沫阻燃性能的影响.结果 表明:由于含氮聚酯多元醇C结构中含有三(2-羟乙基)异氰脲酸酯基团,同时具有氮和异氰脲酸酯的阻燃特性,因此其制得的硬质聚氨酯泡沫氧指数达到27.5％,阻燃性能最佳,同时具有环保、低毒的优点.     

Experimental Study on Residual Mechanical Properties of Bolt-Sphere Joints After a Fire

Through tensile testing of 15 steel bolt-sphere joints and 15 aluminum alloy bolt-sphere joints, influencing rules of material type, high temperature and cooling mode on tensile properties of post-fire bolt-sphere joints were studied, and then failure modes of the joints were determined. According to experimental data, the calculation formula of residual tension capacity of post-fire bolt-sphere joints was presented. Experimental data indicated that (1) decreased extension on the mechanical properties of aluminum alloy bolt-sphere joints after high temperature in the fire was significantly higher than that of the steel bolt-sphere joints; (2) when fire temperature was lower than 800 °C, the tension capacity of steel bolt-sphere joints could be restored by more than 90% after cooling; (3) when fire temperature was lower than 500 °C, the tension capacity of aluminum alloy bolt-sphere joints could be restored by more than 50% after cooling; (4) bolt-sphere joints could still satisfy the requirement of “strong node and weak member” after a fire; and (5) material type and fire temperature were the main factors that influenced post-fire mechanical properties of bolt-sphere joints.     

A New Methodology of Design Fires for Train Carriages Based on Exponential Curve Method

Design fires have great influences on the fire safety concepts and safety measures, and are the basis for any assessment and calculation in tunnel fire safety design. A new methodology of design fires for individual train carriages is proposed based on the exponential design fire curve method and state-of-the-art fire research. The three key parameters required for construction of a design fire are the maximum heat release rate, time to maximum heat release rate, and energy content. An overview of the full scale train carriage fire tests is given and the results show that the maximum heat release rate is in a range of 7 MW to 77 MW and the time to reach the maximum heat release rate varies from 7 min to 118 min. The method could be employed to one single train carriage or several carriages, and alternatively one carriage could be divided into several individual sections. To illustrate the use of the methodology, several engineering applications are presented, including design fires for a metro train carriage with a maximum heat release rate of 77 MW, a double-deck railway train carriage with a maximum heat release rate of 60 MW and a tram carriage with a maximum heat release rate of 28 MW. The main objective is to provide practicing engineers with a flexible and reliable methodology to make design fires for individual train carriages in performance-based tunnel fire safety design.     

Fire Performance of Sandwich Panels in a Modified ISO 13784-1 Small Room Test: The Influence of Increased Fire Load for Different Insulation Materials

Four sandwich panel rooms were constructed as prescribed in the ISO 13784-1 test. However, the construction followed normal industry practice, and the panels were also subjected to the kinds of damage typically found in commercial premises, although such damage may not typically be concentrated in such a small room. The fire load was increased to simulate fires actually occurring in commercial premises by stepping up the propane burner output from the usual maximum of 300–600 kW, and by placing a substantial wooden crib in two of the rooms. The results showed significant differences in fire growth rate and burning behaviour between those panels filled with polyisocyanurate (PIR) and those filled with stone wool in both the experiments without and with the wooden crib. Most significantly, the PIR pyrolysis products caused earlier ignition (by radiation from above) of the wooden crib 11 min into the experiment (1 min after the burner was stepped up to 300 kW), whereas the crib ignited 22 min into the test (2 min after the burner had been stepped up to 600 kW, which is beyond the test standard both in time and heat input) for the stone wool panels. This interaction between building and contents is most often ignored in fire safety assessments. After a few minutes, the PIR pyrolysis products that escaped outside the room, from between the panels, ignited. The extra thermal exposure from the PIR-fuelled flames distorted the panels, which in turn exposed more PIR, resulting in large flames on both the inside and outside of the enclosure. From a fire safety perspective this is most important as it shows that with the large fire loads that are commonly found in commercial premises, steel-faced PIR filled panels are not capable of acting as fire barriers, and may support flame spread through compartment walls and ceilings. In addition, the PIR panelled rooms produced very large quantities of dense smoke and toxic effluents, whereas the stone wool panelled rooms produced small amounts of light smoke of lower toxicity. Furthermore, the experiments showed that modifications to the standard test can lead to extremely different outcomes for some of the products. As the modifications simulated real-life situations, it seems important to discuss whether the standard is robust enough for property safety scenarios encountered in industrial premises.     

阻燃泡沫保温材料燃烧特性研究

分析了对建筑材料燃烧特性研究的方法和原理，确定了依照耗氧原理进行燃烧特性研究的方向，以热释放速率（HRR）、燃烧增长速率指数（FIGRA）、热释放量（THR）为评价参数进行分析。以泡沫保温材料为试验样品，采用中国现行的燃烧性能分级体系同欧洲最新分级体系规定的试验方法进行比较，并对不同原理得到的研究结果进行比较。     

Computational Analysis of Fire Dynamics Inside a Wind Turbine

Wind turbines are generally considered cost-effective, reliable and sustainable energy sources. Fires are not common in wind turbines, but a significant number of fires occur every year due to the large number of turbines installed. Wind turbine fires are difficult to extinguish hence significant damage is expected. Due to the unmanned operation, the probability of a turbine being occupied during a fire is very low. However, operators can do several tasks every week, and hence be exposed to a certain risk. Moreover, there is a general lack of information about how a fire develops inside a wind turbine and the subsequent evolution of the tenability conditions during the time required for an eventual evacuation. Gamesa has been working on fire safety since 2013, using CFD fire modelling to provide insights on wind turbine fire development for the design of emergency procedures. The paper describes a fire hazard analysis performed in a Gamesa’s 2.5 MW turbine. A CFD simulation is carried out to estimate the effects during the first minutes of a typical wind turbine fire in an electrical cabinet. Results show that average oxygen concentration at the nacelle remains above 19.5% during the first 10 min; temperature remains below 60°C for 12 min if measured at 1.5 m; and visibility is on average assured at heights lower than 1.5 m, with values above 5 m during the first 8 min in worse locations, implying no danger for personnel. The potential of this type of analysis to design safer wind turbines under performance-based approaches is clearly demonstrated.     

岩棉材料构件耐火性能研究

岩棉因其良好的保温、隔热、防火、吸声的特性,及其环保、经济、实用的优越性,已越来越多地被工业及建筑业所采用。文章通过对几种以岩棉材料作为主要基材,并加以不同的材料及结构方式进行保护的非承重垂直分隔构件进行耐火极限测试,通过数据分析对影响岩棉建筑构件耐火性能的主要因素作出总结,并提出提高此类构件耐火性能的一些建议。     

Smoke Damage Potentials in Industrial Fire Applications

A methodology is presented for the evaluation of smoke damage contours through the coupling of smoke damage functions, deposition profiles and damage thresholds. Previously developed smoke damage functions and deposition velocities are used to illustrate “far-field” smoke damage potentials both for materials representative of semiconductor fabrication facilities as well as large warehouse storage applications. For semiconductor fabrication, smoke damage associated with leakage current (LC) is important, while smoke staining is of primary interest in warehouse storage. Smoke deposition velocities, a key component to quantifying smoke deposition profiles, were determined in a small (1.0 m³) and large (1,200 m³) enclosure. Both enclosures resulted in comparable values. The velocities ranged from 1.2 to 7.3 × 10^?4 m/s. To determine smoke damage potential contours for semiconductor fabrication facilities, electronic circuit board targets were used. Smoke damage was quantified by LC (i.e., shorting). The average normalized LC values for polyvinylchloride, polycarbonate, and nylon ranged from 0.72 to 6.1 × 10^?4 A m²/g. For warehouse storage facilities, filter targets were used. Smoke damage was quantified by brightness change and odor (i.e., volatile organic compounds, VOC) measurements on the targets. Representative materials were liner board, polystyrene, and polymethyl methacrylate. The smoke damage threshold value for brightness change was 0.012 g/m² and for odor was 0.025 g VOC/m². Resulting contours showed strong radial dependency with distance from the fire/smoke source. Smoke damage reached ~28 m for semiconductor fabrication facilities, while for warehouse storage facilities, it was up to 100 m.