Flammability of oil‐based painted gypsum wallboard subjected to fire heat fluxes

The flammability of painted gypsum wallboard (GWB) exposed to fire heat fluxes is investigated. GWB samples coated with multiple layers of alkyd/oil‐based paint are subjected to constant incident heat fluxes of 35, 50 and 75 kW/m² in the Cone Calorimeter for periods of 5, 10 and 15 min. A number of coats of alkyd/oil‐based interior semi‐gloss enamel paint, including 1, 2, 4, 6 and 8 coats, are applied over a single coat of oil‐based primer to the exposed surface of 16 mm (5/8 in.) thick type X GWB. Unpainted type X GWB is also evaluated under the same exposure conditions. The potential for upward flame spread based on the Cone Calorimeter results is evaluated. The occurrence of paint ‘blistering’ is observed to have a significant effect on the time to ignition and consequently on the potential for upward flame spread. Further work is needed to evaluate the conditions under which ‘blistering’ will occur and its effects on the potential for surface flame spread on painted gypsum wallboard. Copyright © 2004 John Wiley & Sons, Ltd.     

The effects of geometry and ignition mode on ignition times obtained using a cone calorimeter and ISO ignitability apparatus

Three timber-based materials were investigated by subjecting them to a constant uniform heat flux in the range 20–70 kW m^?2 using a Cone Calorimeter and the ISO Ignitability Apparatus. The specimens were examined in the vertical and horizontal orientations in the Cone Calorimeter using gas flame pilot, spark pilot and spontaneous methods of ignition. They were also studied using the ISO Ignitability Apparatus in the normal and inverted horizontal orientations using gas flame pilot and spontaneous methods of ignition. The results obtained are compared by specimen, orientation and mode of ignition.     

乳胶泡沫引火位置对火蔓延特性的影响

利用自行搭建的小尺寸实验平台,开展了对不同点火位置的乳胶泡沫材料燃烧过程的对比实验,通过对火蔓延过程中的部分重要参数（如最大火焰高度、火蔓延速度和蔓延过程中样品表面温度变化等）的测定,分析了点火位置不同时,乳胶泡沫材料的火蔓延特性。结果表明：边缘点火和中间点火条件下,最大火焰高度分别为397和491 mm,火蔓延速度分别为1.8和0.97 mm·s^-1;边缘点火时的乳胶泡沫材料表面火蔓延过程中的温度低于中间点火情况下。     

Evaluation of common ignition models for use with marine cored composites

With the adoption of the High Speed Craft Code the importance of fire safety analytical tools has been elevated. Input data such as ignition properties of cored composite panels will be needed to simulate surface flame spread behaviour. The ease of customizing cored panels for high speed craft means that numerous panel systems are possible on one craft. Understanding how skin thickness and core composition effect ignition is important for efficient evaluation of ignition properties and for fire safety design simulations. To study the effect of skin thickness and core composition, ten material systems were evaluated in a Cone Calorimeter at applied heat fluxes of 20 kWm⁻² to 90 kWm⁻². The systems were a balsa core panel (core thickness 9.5 mm) with three different GRP skins, 1.5 mm, 3 mm and 8 mm, each of the three skins over a copper substrate, the three skins over a ceramic fibreboard substrate and a thermally thick GRP skin. Over the range of applied heat fluxes a change in GRP behaviour from thermally thick to non‐thick was observed. The sensitivity of three simple ignition models to this change was investigated. It was found that the ignition models were not able to resolve the effect of skin thickness and core composition. Copyright © 2000 John Wiley & Sons Ltd.     

不同放置角度的建筑装饰材料PMMA的火焰蔓延特性

为揭示建筑装饰材料聚甲基丙烯酸甲酯(有机玻璃,PMMA)在不同放置角度下的火焰蔓延特性,通过自主搭建的小尺寸火焰蔓延实验平台,研究了宽3 cm、厚2 mm的PMMA试样在不同放置角度下的火焰蔓延特性. 结果表明,放置角度对PMMA火焰蔓延过程中热解区域及预热区长度影响很大,由15°到30°及由?60°到?75°时(顺流火焰蔓延时放置角度为正,逆流火焰蔓延时放置角度为负),平均火焰倾角增加幅度最大. 顺流火焰蔓延的火焰长度随放置角度增加先略减小后逐渐增加,逆流火焰蔓延的火焰长度随放置角度的绝对值增加而略减小. 放置角度由0°到15°时,顺流火焰蔓延的平均速度呈跃变增长,逆流火焰蔓延的平均速度随放置角度绝对值增加而略降低.     

Natural Buoyant Turbulent Diffusion Flame near a Vertical Surface

The structure and dynamics of a natural buoyant turbulent diffusion flame near a vertical surface with combustible gas exhaustion are numerically studied by using the FDS model and computer code. The flame is considered near the surface through which gaseous propylene is injected with a prescribed flow rate. Requirements are determined for the grid cell size in the near-wall region, which ensure sufficient spatial resolution of the boundary layer structure. It is shown that the predicted value of the total heat flux at the surface agrees with the measured results. Investigations of ignition and combustion of a vertical plate of non-charring thermoplastic (polymethylmetacrylate) with allowance for the material pyrolysis reaction show that the ignitor parameters determine the duration of the transient period, but weakly affect the growth of the heat release rate and the height of the pyrolysis region at the stage of developed burning. Significant effects of the ignitor shape, size, and temperature, as well as lateral entrainment of air on the velocity of the upward flame spread rate over the plate surface and on the shape of the pyrolysis front are revealed. The existence of critical parameters of the ignitor separating flame decay from developed burning is demonstrated. Three flame spread regimes with different pyrolysis front shapes are identified.     

The effects of angular orientation and ultraviolet aging on ETFE wire flame spread

This paper considers the solid phase heat conduction along with the effect of ultraviolet (UV) aging on the flame spread and separately discussed the upward and downward flame spread. The 0.15‐mm‐thick ethylene‐tetrafluoro‐ethylene (ETFE) insulated with a 0.5‐mm‐diameter copper core used in the paper. The flame spread was measured at various inclined angles (vertical ± 90^○, to horizontal 0^○) in the directions of gravity assistance (up) and gravity opposition (down). The ETFE was categorized into two groups: the unaged ETFE (ETFE‐U) and the UV aged ETFE (ETFE‐A). The kinetic parameters of samples were obtained from thermogravimetric analysis (TGA) test. The flame spread experimental results showed that the bigger the absolute inclined angle, the higher the flame spread rate. Besides, the effect of UV aging on the upward spread is greater than that of the downward spread. A theoretical system was established through the flame spread experiments and TGA test. The heat flux and the flame spread rate of upward and downward equations were presented to reveal the effects of solid conduction, orientation, inclination, and UV aging on wire flame spread.     

Comparison of Nordtest FIRE 007, CEN draft proposal (Radiant Panel) and Cone Calorimeter methods in the fire testing of floor coverings

Different types of floor coverings were tested using three different methods: the Cone Calorimeter (ISO 5660), the Nordtest floor covering test NT FIRE 007 and the German Radiant Panel Method (DIN 4102 Teil 14). The results of the comparisons between both flame spread and smoke production are given. Some correlation is found between the results of the Cone Calorimeter and the NT FIRE 007. Between other methods, no correlations seem to exist.     

凹型结构下保温材料EPS典型垂直火蔓延特性对比研究

本工作通过自主搭建小尺寸火蔓延的实验平台,研究了凹型结构中保温材料EPS垂直向上和向下火蔓延特性。对比分析了火焰结构特性、火蔓延速度、质量损失速率、火焰温度等参数的变化规律。结果表明,在垂直向上蔓延过程中,EPS出现短暂的停滞现象。一方面由于烟囱效应易形成一个大的浮力压力差,导致火焰不稳定性;另一方面由于凹型结构易于烟气的聚集,导致燃烧不充分。而在垂直向下蔓延过程中,由于逆向烟囱效应的影响,火蔓延速度明显加速。火蔓延过程中质量损失速率,很大程度上受其火焰高度的影响,呈现上下振荡的特性。未燃区域部分,火焰温度经历两个温度峰值,向上蔓延过程中第一个温度峰值大于第二个;而向下蔓延过程中第一个温度峰值小于第二个。这主要是由于火焰结构形态及烟囱效应的方向特点,导致产生两个不同大小的峰值。本研究结果可为实际凹型结构下火蔓延特性研究提供前期理论和参考价值。     

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.     

Evaluating ignition data using the flux time product

A protocol based on the flux time product (FTP)¹ is used to analyze ignition data obtained from the Cone Calorimeter under an impressed flux in the range 20–70 KWm^?2 for different orientations and modes of ignition for conditioned cellulosic materials. The mean, maximum and minimum ignition times are depicted graphically by orientation and mode of ignition. Flux time products, FTP indices, critical irradiances and estimates of the convective heat loss associated with a change in specimen orientation are derived using the mean time-to-ignition data. It is demonstrated that consideration of the thermal thickness of a specimen may not be necessary when the proposed FTP methodology is utilized to determine valid correlations between the time-to-ignition and the incident radiant flux.     

Correlations between pyrolysis combustion flow calorimetry and conventional flammability tests with halogen‐free flame retardant polyolefin compounds

Seven halogen‐free flame retardant (FR) compounds were evaluated using pyrolysis combustion flow calorimetry (PCFC) and cone calorimetry. Performance of wires coated with the compounds was evaluated using industry standard flame tests. The results suggest that time to peak heat release rate (PHRR) and total heat released (THR) in cone calorimetry (and THR and temperature at PHRR in PCFC) be given more attention in FR compound evaluation. Results were analyzed using flame spread theory. As predicted, the lateral flame spread velocity was independent of PHRR and heat release capacity. However, no angular dependence of flame spread velocity was observed. Thus, the thermal theory of ignition and flame spread, which assumes that ignition at the flame front occurs at a particular flame and ignition temperature, provides little insight into the performance of the compounds. However, results are consistent with a heat release rate greater than about 66kW/m² during flame propagation for sustained ignition of insulated wires containing mineral fillers, in agreement with a critical heat release rate criterion for burning. Mineral fillers can reduce heat release rate below the threshold value by lowering the flaming combustion efficiency and fuel content. A rapid screening procedure using PCFC is suggested by logistic regression of the binary (burn/no‐burn) results. Copyright © 2008 John Wiley & Sons, Ltd.     

埃洛石对水性超薄膨胀型钢结构防火涂料防火性能的影响

以聚丙烯酸酯乳液为基体树脂,多聚磷酸铵、三聚氰胺、季戊四醇等为主阻燃剂,埃洛石纳米管(HNTs)为阻燃协效剂,制备了水性超薄膨胀型钢结构防火涂料,采用模拟大板燃烧法和锥形量热仪对其耐火性能进行了研究,并用扫描电镜观察了膨胀炭层的表面形貌。结果表明:HNTs对防火涂料的耐火性能影响显著,当阻燃体系中HNTs含量为10.86%时,HNTs与主阻燃剂之间有阻燃增效作用,所制备防火涂料的耐火时间为107 min,点燃时间为24 s,热释放速率峰值与点燃时间比为4.97,燃烧残余量高达48.36%,且燃烧残余物表面致密,显示出优异的耐火性能。     

Use of the Cone Calorimeter and ConeTools software for development of innovative intumescing graphite systems

The Cone Calorimeter test method has been one of the most used small‐scale fire test method for years now and is at present widely spread over the world. In contrast to many other fire test methods, the Cone Calorimeter provides a range of data with sound scientific basis, which allows a wide range of applications. It can be used for modelling and also for enhanced product development. This paper describes the use of the Cone Calorimeter for the development of new innovative materials in combination with a mathematical model. As example, the cost effective development of an innovative intumescing graphite system for protecting particle board is explained. The performance goal of the project is to obtain the threshold values for a B class in the Single Burning Item (SBI) test method used for the newly developed Euroclass system. The focus of this paper is on the development tools and not on the chemical development of the protective system. During the research it was necessary to develop a new sample holder for the Cone Calorimeter. The results from the project show that the industry can save development time and resources by using the Cone Calorimeter in combination with a simple mathematical model. Copyright © 2010 John Wiley & Sons, Ltd.     

A theoretical basis for flammability properties

Theoretical formulations are presented for the fire growth processes under external radiant heating. They included ignition, burning and energy release rate, and flame spread. The behaviour of these processes with external heating is described along with the critical conditions that limit them. These include the critical heat fluxes for ignition, flame spread and burning rate. It is shown how these processes and their critical conditions depend on a limited number of properties measurable by a number of standard test methods. The properties include heat of combustion, the heat of gasification, ignition temperature and the thermal properties of the material. Alternatively, the properties could be related to parameters easily found from data; namely: (1) the critical heat flux (CHF) for ignition; (2) the slope of the energy release rate with externally imposed flux, defined as heat release parameter (HRP); and (3) the ignition parameter, defined as thermal response parameter (TRP). It is further shown that the flame heat flux differences between small laminar flame ignition sources and larger turbulent flames can affect flame spread due to heat flux and ignition length factors. Finally, it is found that the critical energy release rates theoretically needed for ignition, sustained burning, and turbulent upward flame spread are roughly 13, 52, and 100 kW/m², respectively, and independent of material properties. Copyright © 2005 John Wiley & Sons, Ltd.     

点火位置对乳胶泡沫水平火蔓延规律的影响

为研究点火位置对乳胶泡沫材料水平方向火蔓延规律的影响。搭建小尺寸实验平台,在距离材料中心点0（x1）、3.54 cm（x2）、7.08 cm（x3）、10.62 cm（x4）、14.16 cm（x5）、17.70 cm（x6）位置处点火,研究了试样表面温度、质量损失、火焰高度、火蔓延速度等特性参数的变化规律。结果表明,随着点火位置由材料中心点向边缘点移动,平均火蔓延速度分别为0.24、0.23、0.19、0.31、0.42、0.51 cm·s^-1,呈现先减小后增大的规律;x3点火位置时的平均火焰高度较低,燃烧时间较长,平均质量损失速率较低,主要与火蔓延过程中的热量传递方式有关。研究结果显示了乳胶泡沫的火蔓延过程,得到了点火位置对火蔓延的影响规律。     

倾斜角对液体燃料润湿条件下砂床表面火蔓延的影响

利用纹影系统、CCD相机以及K型热电偶对正丁醇润湿条件下不同角度的砂床表面火蔓延特性进行了研究,分析了不同砂床表面倾角对火蔓延的影响机理。研究结果表明:正丁醇润湿条件下变角度砂床表面火焰是稳定匀速蔓延的,向上蔓延时,火焰的高度、黄色发光区以及蔓延速度随着倾角的增加而增大;向下蔓延时,火焰的高度、黄色发光区以及蔓延速度随着倾角的增加而减小;蔓延火焰前方存在预热区,且预热区随表面倾角的增大而增大:砂层内部存在热边界层,且砂床热边界层厚度随表面倾角的增加而减小。得到的火蔓延特性及燃烧机理为此类液体燃料的储存、使用以及环境保护提供了一定的科学依据。     

Effect of Melting Behaviour on Upward Flame Spread of Thermoplastics

The effect of melting behaviour on upward flame spread of thermoplastic materials when subjected to small ignition sources and considered to suffer no external flux was studied using large-scale tests. For moderate fire conditions the cone calorimeter was utilized, with the sample set in a vertical orientation to study the melting behaviour of the specimens. Under these conditions the results indicate that the melting behaviour significantly affects upward flame spread behaviour. A pool of the melt which formed at the base of the vertically oriented sample tested creates a pool fire which then controls the fire growth and flame spread. In contrast, it was found that some thermoplastic materials which have higher glass transition temperatures or undergo a special pyrolysis process such as depolymerization, intumescing or charring do not experience significant melting behaviour when exposed to the same thermal insult. As a result, they behave very differently in terms of upward flame spread. The study also indicates that the melting behaviour of thermoplastic materials is an important characteristic in fires which should be taken into account in the development of modelling, in particular for upward flame spread models. © 1997 by John Wiley & Sons, Ltd.     

Factors influencing the ignition of flames from air-fired swirl pf burners retrofitted to oxy-fuel

Combustion tests were undertaken in a vertical pilot-scale furnace (1.2 MWt) at the IHI test facility in Aioi, Japan, to compare the performance of an air fired swirl burner retrofitted to oxy fired pf coal combustion with the oxy fired feed conditions established to match the furnace heat transfer for the air fired case. A turn down test at a reduced load was also conducted to study the impact on flame stability and furnace performance.Experimental results include gas temperature measurements using pyrometry to infer the ignition location of the flames, flue gas composition analysis, and residence time and carbon burnout. Theoretical computational fluid dynamics (CFD) modelling studies using the Fluent 6.2 code were made to infer mechanisms for flame ignition changes.Previous research has identified that differences in the gas compositions of air and oxy systems increase particle ignition times and reduce flame propagation velocity in laminar systems. The current study also suggests changes in jet aerodynamics, due to burner primary and secondary velocity differences (and hence the momentum flux ratio of the flows) also influence flame shape and type.For the oxy fuel retrofit considered, the higher momentum flux of the primary stream of the oxy-fuel burner causes the predicted ignition to be delayed and occur further distant from the burner nozzle, with the difference being accentuated at low load. However, the study was limited to experimental flames being all Type-0 (low swirl with no internal recirculation), and therefore future work consider higher swirl flames (with internal recirculation) more common in industry.     

Ignitability measurements with the cone calorimeter

The Cone Calorimeter is a new-generation instrument developed primarily for making rate of heat release measurements. This instrument, containing a uniform and well-characterized irradiance source, was also seen to be useful for making measurements of radiant ignition on materials. Data have now been collected for a wide range of illustrating the performance of similar materials in other apparatuses. Finally, for a selected material, Douglas fir particle board, a detailed comparison with an ignition model has been made.