Experimental investigation into the influence of ignition location on flame spread and heat release rates of polyurethane foam slabs

This study presents the results from a set of 11 large‐scale open fire tests performed on flexible polyurethane foam slabs/mattresses. The purpose of the study was to investigate the influence of the ignition location on the fire behaviour of the foam slabs and to generate data on a highly characterised material that could be used for modelling work in the future. A method for obtaining spatially resolved flame spread data for this type of material was presented using a gridded array of 5 × 10 thermocouples placed on the underside the foam slab and from this, flame spread was examined using three different approaches. The heat release rate (HRR) results showed clear shapes forming that were dependent on the ignition location, with two distinct behaviours being observed between the various different ignition locations, this was also observed in the calculated flame spread rate (FSR) data. Results within an individual test, showed the calculated range of FSRs over the geometry of the slab varied between approximately 1 and 8 mm/s depending on the ignition location. The average FSR values between tests varied between 3 and 7 mm/s and the maximum and minimum values were calculated to be approximately 11 and 2 mm/s respectively.     

Investigation of fire behavior of rigid polyurethane foams containing fly ash and intumescent flame retardant by using a cone calorimeter

Cone calorimeter is one of the most useful bench‐scale equipment which can simulate real‐world fire conditions. Therefore, cone calorimeter tests have been the most important and widely used tests for research and development of fire behavior of polymeric materials. In this study, fire behavior of rigid polyurethane foams containing fly ash (up to 5 wt %) and intumescent flame retardant (up to 5 wt %) composed of ammonium polyphosphate/pentaerythritol was investigated by using a cone calorimeter. In addition, thermogravimetric analysis of the additives and the foams were also carried out to explain the effects of fly ash and intumescent flame retardant on fire behavior of the foams. Experimental results indicated that rigid polyurethane foam containing fly ash and the intumescent flame retardant in comparison with pure rigid polyurethane foam shows significantly enhanced fire resistance and thermal stability. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Apparatus for the vertical orientation cone calorimeter testing of flexible polyurethane foams

Of concern to regulators and fire safety engineers is how flexible polyurethane foam drips and flows during burning. Specifically, flexible polyurethane foam forms a burning ‘pool’ of liquid as the foam decomposes, which can lead to accelerated flashover events. To fully study this phenomenon where the ‘pool fire’ accelerates heat release, large‐scale tests like the furniture calorimeter (American Society of Testing and Materials (ASTM) E1537) are used, and no small‐scale technique exists. In this paper, we present our work in developing a new sample holder that works with a bench‐scale heat release test, the cone calorimeter (ASTM E1354). The holder was built upon designs developed by the National Institute of Standards and Technology, which placed the foam in a cage in a vertical orientation during cone calorimeter testing. In this paper, we show the schematics for this test apparatus, as well as results obtained with this apparatus on four different flexible foams (shape memory and high‐density foam, flame retarded and non‐flame retarded). We compare the results from the vertical testing with that obtained via traditional horizontal ASTM E1354 testing. The advantages and disadvantages of this new apparatus are discussed in this paper. Copyright © 2014 John Wiley & Sons, Ltd.     

Bedding ignition,vertical flame spread and subsequent thermal impact on underlying mattress

The ignition of bedding and subsequent vertical spread of fire along the side of a noncombustible surrogate bed set was investigated. One‐hundred‐eight (108) tests were conducted to assess the ignition timeline and subsequent vertical flame spread of bedding up the side of a bed along with the thermal impact of the bedding fire on the underlying bed set. The ignition source for all tests was comprised of the flame from a book of matches placed on bedding at floor level at the base of the bed. The bedding consisted of combinations of a cotton/polyester blend sheet and bedspread. Ignition occurred in 3 to 10 seconds for the majority of the test. The speed of subsequent vertical flame spread, assessed through video frame analysis tools, was dependent on the exposed bedding material with an exposed sheet exhibiting faster spread. Thermal exposure from the burning bedding to the vertical sides of the bed set was assessed with an array of thermocouples embedded at the surface of the sides of the underlying bed set. The time to thermal exposure was found to be a function of the vertical flame spread and thickness of the bedding material(s).     

Fire safety assessment of wooden facades

The fire behaviour of wooden facades in multi‐storey houses has been studied in a Nordic research project on the fire safety of timber framed buildings. Two different fire scenarios were considered: a relatively small ignition source outside the building and a post‐flashover compartment fire. The scenarios correspond to potential fire situations in sprinklered and unsprinklered houses, respectively. Fire tests of wooden facades with different cladding materials, surface treatments and structures were performed on intermediate and large scales. In the case of an external fire, the most efficient way to prevent the propagation of flames to the upper storeys of the facade is the structural modification of the facade profile, i.e. cantilevers and oriels. Particular care should be taken so that the protrusion is of sufficient depth and width and that its front and lower surfaces are non‐combustible. Using fire retardant treatment, the flame spread can be considerably delayed or even halted. Acceptance criteria for the facades of sprinklered and unsprinklered multi‐storey buildings are suggested based on the test series. Similar principles can be applied when defining criteria for various test arrangements and fire scenarios. Copyright © 2002 John Wiley & Sons, Ltd.     

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.     

阻燃聚氨酯硬泡的研究进展简

本文介绍了聚氨酯硬泡的阻燃必要性及硬质聚氨酯泡沫中常用的阻燃剂,并展望了阻燃聚氨酯硬泡的发展前景.     

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.     

阻燃型硬质聚氨酯泡沫塑料研究进展

对硬质聚氨酯泡沫塑料燃烧机制、阻燃剂的阻燃原理以及硬泡常用阻燃剂进行了全面综述,并总结了阻燃硬质泡沫塑料待研究解决的相关技术问题,提出了相应的研究思路,最后阐述了硬质泡沫塑料阻燃发展前景。     

三聚氰胺氰尿酸盐阻燃聚氨酯硬泡

将三聚氰胺氰尿酸盐(MCA)作为阻燃剂,采用一步全水发泡法,制备一系列硬质聚氨酯泡沫/三聚氰胺氰尿酸盐复合材料(RPUF/MCA),采用扫描电子显微镜(SEM)、热重分析(TG)、极限氧指数(LOI)、UL-94垂直燃烧、烟密度测试、傅立叶红外光谱(FT-IR)及拉曼光谱表征,研究了MCA对硬质聚氨酯泡沫(RPUF)泡孔结构、热稳定性、阻燃性及燃烧烟气密度的影响。研究表明,MCA能够显著提高RPUF/MCA的阻燃性能,30份的MCA使RPUF/MCA30达到UL-94 V-1级别,极限氧指数达到22.0%。热重测试结果表明,MCA的添加使成炭率降低;同时发现,MCA的添加降低了RPUF/MCA泡沫复合材料的初始热分解温度和复合材料的燃烧烟气密度,有效地提高了复合材料火灾安全性能。     

Fire spread from an open‐doors electrical cabinet to neighboring targets in a confined and mechanically ventilated facility

Electrical cabinet fire is one of the main fire hazards in nuclear power plants. As part of the OECD PRISME‐2 programme, four fire tests were carried out to investigate the fire spread from an open‐doors electrical cabinet to overhead cable trays and adjacent cabinets in a confined and mechanically ventilated facility. These tests, named CFS‐5 to CFS‐7 and CORE‐6, used same both cabinet (fire source) and three overhead cable trays. The trays were filled with a halogenated flame‐retardant cable‐type for CFS‐5 and one halogen‐free for the three other tests. Moreover, fire dampers were used for CFS‐7 test while CORE‐6 test implemented two additional cabinets adjacent to the fire source. Measurements such as flame and gas temperature, gas concentration, mass loss rate, and heat release rate were performed for investigating the fire spread. Cabinet fire spread to the cable trays for CFS‐5 and CFS‐6 tests. Three fast and short cable tray fires were shown for CFS‐5, while a slow and long cable tray fire was highlighted for CFS‐6. In contrast, the fire dampers shutdown for CFS‐7 test prevented ignition of the overhead cables. Furthermore, for CORE‐6 test, cabinet fire spread to the adjacent cabinets, but the upper cables were not ignited.     

Relationship between the thermal degradation chemistry and flammability of commercial flexible polyurethane foams

In this article, we report the use of a variety of analytical methods, in particular, solid‐state ¹H‐NMR and ¹³C‐NMR to characterize the relationship between the condensed‐phase chemistry and burning behavior as determined by a series of combustion tests for two commercially derived flexible polyurethane foams, one combustion‐modified. The combustion tests showed that the foams met several regulatory requirements in terms of their fire performance, whether or not they were combustion‐modified. Both foams passed the MV SS 302 and CAL 117 small‐flame tests. The nonmodified foam failed the Crib 5 test, but this test had a much larger ignition source. The particular problem with the nonmodified foam was melt drip into the flame zone. This led to a steady maintenance of the fuel feed and a rapid escalation of the fire. In contrast, the combustion‐modified foam showed little melt drip and self‐extinguished. Thermal analysis data for the two foams showed that melamine acted in part as an endothermic heat sink. This alone did not account for the much reduced melt flow and drip of the combustion‐modified foam, but the solid‐state ¹H‐NMR data clearly showed that the molecular mobility of the combustion char from combustion‐modified foam was lower than the unmodified foam char, which indicated that the flame‐retardant formulation in the combustion‐modified foam acted by a condensed‐phase mechanism. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3024–3033, 2006     

Numerical simulation of the fire behaviour of facade equipped with aluminium composite material‐based claddings‐Model validation at large scale

The recent fire events in buildings involving combustible cladding systems have raised concerns regarding the risk that these systems can pose. Understanding such facade fires is complex as they involve a combination of various products and system. Facade fire propagation tests at ISO 13785‐1 intermediate scale were performed on different combinations of aluminium composite material (ACM) claddings and insulants. Simulations were addressed to reproduce these tests and were validated in terms of thermal conditions in the system. This allowed additional investigation and understanding of fire propagation on the facade and more accurate determination of the fire behaviour of the overall system. In this paper, the scaling influence on the fire behaviour of ACM clad systems is investigated with simulations performed to reproduce fire tests at the BS8414‐1 larger scale on three different combinations of ACM and insulants. The contributions of the cladding and insulant were numerically investigated. The fire behaviour of each component and of the overall system is validated by comparison with experiments. Simulations and tests show that the ACM cladding is the most important element driving the global fire behaviour of the systems. In particular, ACM‐PE‐based cladding systems, whatever the insulant, show extensive fire propagation while its degradation affects the integrity of the cavity.     

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。     

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.     

Fire performance of external wall claddings under a performance-based building code

New Zealand Building Code Performance requirements relating to fire performance of external walls are considered and methods of evaluating the potential for vertical fire spread are discussed. Classifying external wall claddings on the basis of performance in the ‘combustibility’ test has proved overly restrictive where some external cladding materials are concerned. Performance criteria based on heat relase or ‘degree of combustibility’ are proposed and they seem to provide a better classification scheme for external wall cladding materials. Heat release test data for ten different external wall cladding materials are presented.     

Carbon Nanotube Multilayer Nanocoatings Prevent Flame Spread on Flexible Polyurethane Foam

In an effort to protect polyurethane foam (commonly used as cushioning in upholstered furniture) from fire using environmentally benign chemistries, nanocomposite thin films are deposited using water‐based solutions of cationic‐ and anionic‐stabilized multiwalled carbon nanotubes (MWCNTs). The open‐celled foam is coated using layer‐by‐layer (LbL) assembly to produce uniform protective layers up to 600 nm thick, comprised of cationic polyethylenimine modified with pyrene (PEI‐Py), anionic poly(acrylic acid) (PAA), and MWCNT. Film thickness is found to rely heavily on the PAA‐stabilized MWCNT solution. Coatings of only six [PEI‐Py/PAA+MWCNT] bilayers (BL) show tremendous reductions in peak heat release rate (up to 67%) and total smoke release (up to 80%) for the polyurethane foam. This same coating significantly improves the performance of the polyurethane when exposed to horizontal and vertical flame tests. With 9 BL, the foam successfully withstands a vertical burn test, self‐extinguishing immediately after removal of the test flame. These dramatic reductions in foam flammability are unprecedented and are attributed to the protective nature of the carbon‐based char formed from the coating that acts as a protective barrier.

     

Ignitability test for building materials: influence of fuel gases and the design of the Burner's flame stabilizer on test results

In the harmonization of the European test codes in the context of preventive fire‐protection techniques for buildings, the single flame source test is to be adopted as a European test method. This method is used to evaluate the fire behaviour of a building material subjected to an impingement by a small flame, e.g. the flame of a match. The technique is used to provide evidence in the determination of whether a building material may be assigned the Euroclass E. Building materials that do not meet the requirements of this building material class are designated as Euroclass F. The Federal Institute of Material Research and Testing (BAM) has looked into the question of whether the design of the flame stabilizer of the burner and the use of three different fuel gases (propane, butane and methane) affect the assignation of building materials to a Euroclass, particularly the area between Euroclass E and F. The evaluation showed that the minimum thickness timber boards required to meet Euroclass E requirements would be reduced by approximately 10% when butane and an output stabilizer equipped with a punch disc was used. This means that under modified test conditions, certain timber materials previously assigned to Euroclass F would now be designated Euroclass E. Consequently the safety standard regarding fire protection in buildings may be compromised. Copyright © 1999 John Wiley & Sons, Ltd.     

Preparation and mechanism study of intrinsic hard segment flame-retardant polyurethane foam

The hard segment of polyurethane foam (PUF) plays a special role in degradation and carbonization. In this work, flame-retardant hard segment (HSFR) used to promote fire resistance was synthesized successfully. The limiting oxygen index (LOI), vertical combustion, and micro-combustion calorimetry tests indicated the flame retardancy of the foam was elevated by introducing HSFR. When HSFR with an addition of 60 phr, the LOI value was increased from 17.0 to 25.5%, UL-94 reached V-0 rating, the peak heat release rate (p-HRR) and total heat release (THR) decreased by 63.9% and 10.0%, respectively. In addition, the compressive strength of HSFR-60 increased by five times. Further, the flame-retardant mechanism of HSFR was proposed. In vapor phase, HSFR could generate PO and PO₂, which combine with flammable free radical and hinder segment decomposition. In condensed phase, HSFR could promote the dehydration and carbonization of chain and the formation of dense and graphitized char. This article provides a practical method for the preparation of green, highly effective, and durable flame-retardant PUF.     

聚氨酯泡沫塑料的阻燃

简要介绍了对多孔性材料聚氨酯泡沫塑料进行阻燃处理的重要性，并对各类阻燃剂的阻燃机理以及聚氨酯泡沫塑料阻燃研究领域的技术进展进行了介绍。较全面地综述了改善软质和硬质聚氨酯泡沫塑料阻燃性能的方法，包括：各种添加型阻燃剂和反应型阻燃剂的特点及使用效果，不同阻燃剂的协同作用，引入异氰脲酸酯基团提高硬泡阻燃性能，采用阻燃剂溶液浸渍开孔泡沫塑料等。