A comparison of fire retarded and non‐fire retarded wood‐based wall linings exposed to fire in an enclosure

Full‐scale fire experiments were carried out in an ISO room to study the behaviour of commonly used cellulosic lining materials in real fire conditions. In addition to the temperature measurements recommended by the ISO 9705, temperature recordings were made at each node of grid lines on the wall lining surfaces. Four lining materials were chosen to represent different types of products and the surface spread of classifications determined using the BS 476 Part 7 flame spread test environment. The linings included fire retarded, melamine faced and non‐fire retarded boards which facilitated a comparative study of the behaviour of these materials with respect to ignition, flame spread, heat release rate and time to flashover. Corner fire scenarios were used in all the experiments. A T shape flame spread pattern on the surface of the two adjacent walls was observed prior to flashover. Prior to the onset of flashover conditions, downward opposed flow surface flame spread to the wall/ceiling intersection. For the non‐retarded wood based materials, such as plywood and medium density fibre board, flashover conditions occurred approximately 4 min after the start of the experiment. However, the fire retarded chipboard ignition was delayed by some 11 min 45 s after which flame spread was very rapid with flashover occurring within a further 1 min 45 s. An explanation for this particular behaviour is the considerable pre‐heating which occurred during the pre‐ignition period. For the fire retarded linings, much higher surface temperatures were recorded compared with those for non‐fire retarded linings. It was found that the areas of the fire retarded linings facing the source flame suffered extensive pyrolysis and charring which penetrated to the rear surface of the lining. Copyright © 1999 John Wiley & Sons, Ltd.     

Some factors influencing fire spread over room linings and in the ASTM E–84 tunnel test

An examination of the correlative relationship between room fire intensity (temperature) and flammability data for materials, ASTM E–84 flame ratings and energy release rate from calorimertry devices is presented for fire spread on lings. The results of the analysis show the significance of two modes of flame spread—wind-aided and opposed-flow spread. The factors important in these spread modes are considered from approximate solutions developed for turbulent flow. As the importance of energy release rate to flame spread in the tunnel test (E–84) and in upward or wind-aided spread is illustrated. The results suggest a possible reason why the ASTM E–84 and in upward or wind-aided spread is illustrated. The results suggest a possible reason why the ASTM E–84 ratings may not be applicable to the performance of low-density combustible linings in wall fires. In the analyses, flame radiation has not been considered. Also the interpretation of energy release rate data for difference scale and orientation effects has been ignored. These two factors must ultimately be addressed.     

固体推进剂燃烧诱发热烟气运动的大涡模拟

利用空间火蔓延与烟气运动的大涡模拟方法,探讨了固体推进剂燃烧时在舱室内形成的火蔓延和烟气的运动,计算出室内烟气温度、墙壁温度与地面热流密度随时间的变化,与试验结果相符合.计算结果表明,固体推进剂火灾初期室内的气体受到热烟气的挤压像受到活塞的推挤一样流出门口;顶棚温度出现位于靠近火源和通风口连接通道所处的垂直截面附近的局...     

Study on flashover in a single chamber lined with combustible materials

With the theories of fire dynamics and relevant parameters of combustible lining materials, a predicted model of hot gas layer temperature during pre‐flashover stage of enclosure fires was established, and the effects of lining materials on the likelihood of flashover were theoretically analyzed. By using common commercial lining materials, such as wall papers, foam plastics, wood‐based panels, and fabric‐upholstered wall panel, the phenomenon of flashover was reproduced in a small‐scale firebox of 1/4 sizes of ISO 9705 test chamber. By comparing the theoretical results with experimental data, the equation predicting the hot gas layer of quasi‐steady enclosure fires was gained; an indicator I_FO to reflect overall the hazards of flashover and to classify flashover fires was proposed, and its application was initially studied. The study results can be helpful to explain further and overall the effects of lining materials on enclosure fires and can be used to guide the prevention of flashover by choosing appropriate interior decoration materials. Copyright © 2012 John Wiley & Sons, Ltd.     

Comparison of test protocols for the standard room/corner test

As part of international efforts to evaluate alternative reaction‐to‐fire tests, several series of room/corner tests have been conducted. Materials tested were mostly different wood products but included gypsum board and a few foam plastics. This is a review of the overall results of related studies in which the different test protocols for the standard room/corner test were used. Differences in the test protocols involved two options for the ignition burner scenario and whether or not the ceiling was also lined with the test materials. The test materials were placed on three walls of the room in all the tests. The two burner scenarios were (1) 40 kW for 300 s followed by 160 kW for 300 s and (2) 100 kW for 600 s and 300 kW for 600 s. The 40 and 160 kW burner scenario without the ceiling lined did not provide a severe enough test for flashover to occur with fire‐retardant‐treated materials. Use of the 100 and 300 kW burner scenario without lining the ceiling provided the ability to differentiate between wood products with ASTM E 84 flame spread indexes of 70 to 125 and those with higher flame spread indexes. Lining the ceiling with test material creates a more severe test.     

Studies of the combined effects of some important factors on the likelihood of flashover

Among those factors that affect the likelihood of flashover in enclosure fires, the thermal inertia of lining materials, ventilation factor of door openings, heat release rate of fuel, and internal dimensions of the enclosure are the most important. The effects of the four factors are related, so it is very necessary to study their combined effects. In the present study, based on analyzing the approximate heat balance on the control volume similar to that in the MQH method, a dimensional relationship was derived that facilitates the estimation of pre‐flashover temperatures, which is used in the popular guidance literature as the key parameters for practical methods of predicting flashover. By correlating a vast amount of data gained in both small‐scale and large‐scale enclosure fire experiments, an important equation was obtained, which can embody explicitly and quantitatively the combined effects of the four important factors on the likelihood of flashover. According to the temperature criteria of 600°C identifying flashover, a new ‘combined method of predicting flashover’ was put forward. The validity of the method was verified in small‐scale experiments, and the results showed that it could be applied to predict well whether flashover occurs in enclosure fires or not. Copyright © 2010 John Wiley & Sons, Ltd.     

The early fire behaviour of combustible wall lining materials

The development of the Australian Standard AS 1530 Part 3 ‘Test for Early Fire Hazard Properties of Materials’ from the study of the fire behavior of cellulosic wall linings in simulated room fires has been outlined. Similar studies for assessing a wider range of wall linings are now reported including various plastic facings applied to hardboard. Using similar parameters for ignitability, spread of flame, heat evolved and smoke developed, the behaviors of the linings in the standard test have been compared to the behavior in corner-wall burns. Two methods of ignition were used for the burns; (a) timber cribs; and (b) impressed radiant heat with a pilot flame. The results are discussed in terms of the validity of the standard test as a multi-parameter assessment of materials in a fire hazard situation. The test has been validated for the wider range of wall lining materials.     

Experimental study on fire hazard of typical curtain materials in ISO 9705 fire test room

Curtain materials are commonly used as decoration, shade, or screen. They are flammable and are usually across a large part of a room, leading to the risk of a high fire hazard. Once ignited, the upward fire spread would accelerate the fire development in an enclosure. In this paper, fire hazard of three typical curtain materials with different pleat rates were tested in an ISO 9705 fire test room. Fire parameters such as temperature field, flame spread rate, heat release rate (HRR), and emitted gases, and the influences of pleat rate and cotton content on flame spread rate were investigated. The correlation between flame spread rate and HRR was discussed. The results show that the upward flame spread has an accelerating rate, and an inverted‐triangle burning area would emerge during the combustion. Some horizontal fibrillar structures appear in this burning area. Pleat rate and cotton content have considerable influence on the curtain fire behavior. The flame spread rate shows a linear response to HRR at the early stage. In addition, a function between average flame spread rate and pleat rate for engineering estimation is proposed, and a linear relationship between HRR/m_CO and m/m_CO has been obtained. The study results provide valuable reference to building fire simulation and safety design. Copyright © 2011 John Wiley & Sons, Ltd.     

Physical modelling fire performance of wall-covering materials

A small-scale enclosure was constructed for characterizing the contribution of interior finish wall-lining materials to fire growth in compartments. The enclosure was based upon refinements to a design devised by scientists at the National Institute for Standards and Technology for quarter-scale modelling of room fire tests on interior-finish materials. A large volume of evidence is presented demonstrating how this small-scale enclosure could provide the information about surface flammability, heat release, smoke generation and contribution to fire growth that is required for a reasonable assessment of the fire performance of interior wall-finish materials.     

竖直射流火撞击障碍管道数值模拟分析

当前对于竖直向上屏障射流火的研究大多集中于顶棚射流,对于竖直向上射流火羽流撞击管道的研究相对较少。为研究竖直向上射流火羽流撞击管道的特征演化行为,基于燃烧学及流体力学基本原理,运用Fluent数值模拟软件,通过控制变量法对不同热释放速率、障碍管道直径及管壁-火源间距因素进行探究。研究表明障碍管道直径和管壁-火源间距对火焰高度和宽度均有一定程度的影响,且得到了基于Froude数的无量纲火焰高度表征模型。     

竖直射流火撞击障碍管道数值模拟分析

当前对于竖直向上屏障射流火的研究大多集中于顶棚射流,对于竖直向上射流火羽流撞击管道的研究相对较少。为研究竖直向上射流火羽流撞击管道的特征演化行为,基于燃烧学及流体力学基本原理,运用Fluent数值模拟软件,通过控制变量法对不同热释放速率、障碍管道直径及管壁-火源间距因素进行探究。研究表明障碍管道直径和管壁-火源间距对火焰高度和宽度均有一定程度的影响,且得到了基于Froude数的无量纲火焰高度表征模型。     

An experimental and modeling study of heat radiation characteristics of inclined ceiling jet in an airplane cargo compartment

A series of pool fires were carried out in an airplane cargo compartment to investigate the effect of the pressure on the heat radiation flux (HRF) of the inclined ceiling jet fire. During the tests, different static chamber pressures ranging from 50 to 101 kPa were controlled by the air flow in and out; both free fire and inclined ceiling jet fire were conducted with five different heat release rates (HRRs), which were produced by a 17‐cm square porous gas burner using propane as fuel. Vertical flame temperature, thermal plume temperature beneath the inclined ceiling, and HRF to the horizontal floor were measured and analyzed; at the same time, the flame shape was recorded by a video. It was found that the HRF was increased with the HRR, and there was a sudden rise for these fire impinging on the ceiling. The flame radiation fraction had a weak correlation with the environment pressure, while the flame emissivity was increased with the increasing ambient pressure. Besides, on the basis of the assumption that the flame emissivity is equaled in both free flame and the inclined ceiling jet fire, HRF calculated model was established and compared with the experimental results.     

Ceiling heat transfer during fire plume and fire impingement

The impingement of turbulent fires and fire plumes on a horizontal ceiling was considered. Free flame heights, impinging flame lengths along the ceiling and ceiling heat fluxes were measured for both unconfined and confined ceilings. The study was limited to the initial stage of ceiling heating by fire under conditions where convection dominates the flow. Fire sources were simulated by burning liquid methanol, ethanol, 1-propanol or n-pentane from the top surface of a cylindrical wick. Test variables include fire heat release rate of 50–7890 W, ceiling diameters of 610 and 660 mm, ceiling heights of 58–940 mm, wick diameters of 10–107 mm and curtain wall lengths (for confined ceilings) as large as the ceiling height. Simplified models were employed to suggest expressions for data correlation. Flame lengths increased up to 40% when the ceiling was confined. Ceiling heat fluxes were relatively independent of position in the stagnation region (radius along ceiling <20% of the ceiling height). Heat fluxes in the stagnation region for plumes were 25–40% of those measured for impinging jets at comparable conditions. In the ceiling jet region, at larger distances from the point of impingement, the heat flux decreased with increasing radius, in agreement with other studies. Confinement tended to increase ceiling heat fluxes in both regions. Ceiling heat fluxes for impinging flames and plumes were approximately the same, for flame lengths along the ceiling up to 25% of the ceiling height; however, stagnation point heat fluxes decreased for longer flame lengths.     

Rate of heat release and ignitability indices for surface linings

Dimensional analysis is applied to one form of fire growth in a compartment to derive two indices for the classification of linings, an ignitability index and a rate of heat release index, that can be combined into a fire growth parameter, which here is made proportional to the time to flashover in the internationally standardized Room/Corner Test. The ignitability index is the inverse of the time to ignition. The rate of heat release index is obtained by integrating the rate of heat release in time, weighted in such a way that the values of rate of heat release immediately after ignition are of higher importance than those at later times. Both indices are determined from test results of the Cone Calorimeter.     

Application of test results to analysis and control of fire growth hazards

Some examples of the application of fire tests to hazard and risk assessment and some of the problems to be encountered are described. Reference is made to theoretical studies designed to show how to obtain basic data on material properties from ignitability and flame spread tests, and recent correlations of the rate of heat release required to cause flashover are presented. Progress in predicting fire growth from theory for certain idealized conditions will increasingly condition the choice of which processes shall be the subject of tests.     

Impact of flat roof–integrated solar photovoltaic installation mode on building fire safety

This paper quantifies experimentally the fire‐induced reradiation to roof surface created by flame extension on the back of the flat roof–integrated photovoltaic (PV) array. A gas burner underneath the tilted PV panels was employed as the fire source. The effects of the PV tilt angle, distance from PV panel to roof, and fire heat release rate (HRR) were investigated. The flame extension geometries and flame reradiation heat flux distribution were recorded. The results show that the flame extension length and vertical thickness (ie, the vertical distance from the back surface of the PV panel to the extension flame profile) are reduced with the increase of PV tilt angle and panel‐roof distance but are increased with increases in the fire HRR. A unified nondimensional HRR coupled with all these factors is proposed to quantify the flame extension geometry. Furthermore, a general equation based on the physical relationship between flame radiation and flame geometry is developed to characterize the distribution of reradiation heat flux on the roof surface with the nondimensional local flame thickness. Finally, suggestions regarding PV installations on flat roofs and the selection of roofing materials are given to decrease the possibility of flame propagation underneath the PV arrays.     

Correlation between cone calorimeter data and time to flashover in the room fire test

Correlations based on linear regressions between data as time to ignition and heat release in the cone calorimeter and time to flashover in the room fire test have been developed. They are a further development of an earlier approach which has been modified and extended to a wider range of surface linings. The correlations apply so far only to surface linings on both walls and ceilings. When the density of the linings as a simplified measure of the thermal inertia is included, the correlations are improved significantly. The new correlations are based on data readily available from the cone calorimeter test at one heat flux level, 50 kWm^?2. The correlation coefficient for the basic relationship, including the density of the linings, is now 0.98 when applied to the 13 linings investigated earlier. This is slightly better than the previous study, in which the best correlation coefficient was 0.96. When applied to 28 linings, the correlation coefficient remains about the same (0.97). Very similar regression equations have been obtained when analysing only 13 products and all 28. This is a strong indication of the general predictive capacity of this approach. The inclusion of other data such as thickness of linings or mass loss during fire does not improve the correlation coefficients. The approach is quite straightforward and simple. However, it has provided a useful prediction which is also valid for an extended range of linings.     

Flame extension and the near field under the ceiling for travelling fires inside large compartments

Structures need to be designed to maintain their stability in the event of a fire. The travelling fire methodology (TFM) defines the thermal boundary condition for structural design of large compartments of fires that do not flashover, considering near field and far field regions. TFM assumes a near field temperature of 1200°C, where the flame is impinging on the ceiling without any extension and gives the temperature of the hot gases in the far field from Alpert correlations. This paper revisits the near field assumptions of the TFM and, for the first time, includes horizontal flame extension under the ceiling, which affects the heating exposure of the structural members thus their load-bearing capacity. It also formulates the thermal boundary condition in terms of heat flux rather than in terms of temperature as it is used in TFM, which allows for a more formal treatment of heat transfer. The Hasemi, Wakamatsu, and Lattimer models of heat flux from flame are investigated for the near field. The methodology is applied to an open-plan generic office compartment with a floor area of 960 m² and 3.60 m high with concrete and with protected and unprotected steel structural members. The near field length with flame extension (fTFM) is found to be between 1.5 and 6.5 times longer than without flame extension. The duration of the exposure to peak heat flux depends on the flame length, which is 53 min for fTFM compared with 17 min for TFM, in the case of a slow 5% floor area fire. The peak heat flux is from 112 to 236 kW/m² for the majority of fire sizes using the Wakamatsu model and from 80 to 120 kW/m² for the Hasemi and Lattimer models, compared with 215 to 228 kW/m² for TFM. The results show that for all cases, TFM results in higher structural temperatures compared with different fTFM models (600°C for concrete rebar and 800°C for protected steel beam), except for the Wakamatsu model that for small fires, leads to approximately 20% higher temperatures than TFM. These findings mitigate the uncertainty around the TFM near field model and confirm that it is conservative for calculation of the thermal load on structures. This study contributes to the creation of design tools for better structural fire engineering.     

Fire testing flat roofs and wall linings with point fire sources

In the spring of 1977 seven real scale fire tests on flat roofs and wall linings were carried out with relatively small fire loads to simulate the early stages of a fire. Tests with large fire loads had already been performed. Five tests were carried out on insulated corrugated steel roof decks with a fire-retardant EPS (expanded polystyrene) foam insulation of reduced flammability and one test with a non-combustible mineral-wool insulation. A seventh test was run to study the fire behaviour of corrugated asbestos cement roofs and wall linings with EPS foam insulations and fire loads of the same kind (wood cribs up to 200 kg) as before. The tests demonstrated both the advantages and the disadvantages of the different insulations for corrugated steel roof decks in case of fires before Flash-over.     

不饱和聚酯玻璃钢吊顶的阻燃探讨

本文主要围绕建筑场馆屋面装饰中采用不饱和聚酯玻璃钢吊顶的阻燃性开展工作，对选择的阻燃剂品种、阻燃配方进行实验研究。并做出评价和确定。