Experimental study of the influence of interior lining distributions on flashover in the enclosure with different ceiling structures

Different distributions of interior linings in an enclosure have been studied to reveal the influence on time to flashover. Two kinds of ceiling structures, flat ceiling and flat ceiling with beams, were used for enclosure. Six full‐scale experiments were performed to investigate the occurrence of flashover in large enclosures. Heat release rate, gas temperature, and surface temperature of the enclosure were measured and analyzed. Experimental results show that time to flashover is extended for enclosure with large surface areas and large doors. Whether lining the interior linings on the ceiling or beams has a significant effect on flashover. Considering that ceiling fires have effect on the progress of the spread of flame on the wall, time to flashover is reduced for the tests that are fitted with the interior linings on the wall of the enclosure. In the enclosure with beams, the direction of spread of flame on the ceiling is changed, resulting in the change of time to flashover. Additionally, the strength of ceiling jets that is affected by the heat release rate of fire source and the area of the interior linings mounted on the fire source influenced region affects flashover. It is observed that flashover occurs when flame fronts are throughout the upper part of the back wall and the flame‐covered area on the back wall exceeds 0.2 times the area of the back wall.     

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.     

The piloted transition to flaming in smoldering fire retarded and non‐fire retarded polyurethane foam

The piloted transition from smoldering to flaming, though a significant fire safety concern, has not been previously extensively studied. Experimental results are presented on the piloted transition from smoldering to flaming in non‐fire retarded (NFR) polyurethane foam and the fire retarded polyurethane foam Pyrell^®. The samples are small blocks, vertically placed in the wall of an upward wind tunnel. The free surface is exposed to an oxidizer flow and a radiant heat flux. The smolder product gases pass upwards through a pilot. The experiments on NFR foam show that the smolder velocity and peak smolder temperature, which increase with the oxygen concentration and heat flux, are strongly correlated to the transition to flaming event, in that there are minimum values of these parameters for transition to occur. The existence of a minimum smolder velocity for ignition supports the concept of a gaseous mixture reaching a lean flammability limit as the criterion for the transition to flaming. To compensate for the solid‐ and gas‐phase effects of the fire retardants on the piloted transition in Pyrell, it was necessary to increase the oxygen concentration and the power supplied to the smolder igniter and the pilot. The piloted transition is observed in oxygen concentrations above 17% in NFR foam and above 23% in Pyrell. The results show that although Pyrell is less flammable than NFR foam, it is still susceptible to smoldering and the piloted transition to flaming in oxygen‐enriched environments, which is of interest for special applications such as future space missions. Copyright © 2008 John Wiley & Sons, Ltd.     

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.     

Australian studies on fire hazard tests for internal linings of buildings

The Australian Standard ‘Test for Early Fire Hazard Properties of Materials’ (AS 1530 Part 3, 1976) has been studied in detail as a method of assessing the fire performance of plastics wall linings under the conditions of early fire development in a room. A particular feature of the standard test is that four parameters characterizing the reaction to fire are measured concurrently. Results from the standard test have been compared to corner-wall burns involving the same parameters as in the standard test. The suitability of these parameters and the ability of the standard test to rank the behaviour of the materials in the same order as indicated by corner-wall burns is discussed. A general relationship between ignition time and flame spread was observed and is discussed as support for the concept of concurrent measurement of different reaction-to-fire parameters under the one test procedure and condition.     

Thermal properties of polyethylene flame retarded with expandable graphite and intumescent fire retardant additives

Low‐density polyethylene was flame retarded by combinations of expandable graphite with either ethylenediamine phosphate or 3,5‐diaminobenzoic acid phosphate. Cone calorimeter, laser pyrolysis, and open flame exposure tests (supported by video and infrared camera data capture and analysis) were conducted to assess ignition and burn behavior. Cone calorimeter results indicated substantial reductions in the peak heat release rates for all flame‐retarded samples but with reduced ignition times and increased flame out times. Smoke generation was suppressed in the presence of expandable graphite. Infrared and video data from open flame fire tests indicated cohesive bonding of expanded strings and thermal shielding properties in all binary systems. All binary systems delivered fire retardation exceeding any of the single fire retardant compounds. They were also able to withstand higher temperatures before ignition, burn through, or sag occurred. All ethylenediamine phosphate‐containing binary systems prevented sample burn through, maintaining structural integrity of samples until eventual melting of the polymer media occurred. Thermogravimetric analysis laser pyrolysis results confirmed the good thermal shielding imparted by the intumescent additives. Copyright © 2016 John Wiley & Sons, Ltd.     

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.     

Effects of ageing on the fire behaviour of flame‐retarded polymers: a review

The influence of environmental ageing on the reaction to fire of flame‐retarded polymers is reviewed. Six types of stimuli have been identified as the most relevant parameters inducing fire behaviour modification: temperature, moisture, UV radiation, ionizing radiation, chemical solvent and physical stress. This review provides a state of the art and current comprehension of the effects of ageing on flame retardancy of polymers. Various physical and chemical phenomena lead to ageing and deterioration (or sometimes improvement) of the flame retardancy of polymers: release of additives (not only flame retardants) through thermal migration, solubilization, abrasion, etc., chemical degradation of the flame‐retardant system, and chemical or physical modification of the polymer structure (chain scission, crosslinking, diffusion of water, etc.). Obviously, ageing effects strongly depend on the material and the ageing scenario considered. Solutions to maintain flame‐retardant efficiency in aggressive conditions are also presented. © 2014 Society of Chemical Industry     

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.     

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.     

Heat release rate and computer fire modelling vs real‐scale fire tests in passenger trains

The materials and products used in passenger trains may not be the first ignited element, but during the fire development, these materials, especially ceiling linings and wall coverings, contribute significantly to the fire growth. The fire safety requirements in passenger trains consist mainly of bench‐scale tests, with particular focus on the sample geometry, position and fire exposition. When this information is extrapolated to real end use conditions limitations appear. In this paper, a discussion of the use of fire dynamics simulator model and heat release rate experiments in cone calorimeter (bench‐scale test) is presented in order to represent the fire development in a passenger train compartment. For the study, two fire scenarios were selected: (1) the single burning item SBI test (modified) and (2) a passenger train compartment. Initially, the limitations of the assumptions and hypothesis made when producing the model were analyzed and the research team carried out a sensitivity study of the model results considering different grid sizes. In order to validate the model, both bench‐ and full‐scale fire tests were considered based on the results provided by the European research program FIRESTARR. The limitations and uncertainties in the results demonstrate the importance of two basic factors: the incident heat flux in the cone calorimeter tests and the prescribed ignition temperature. Copyright © 2008 John Wiley & Sons, Ltd.     

Assessment of fire behaviour of high‐speed trains' interior materials: small‐scale and full‐scale fire tests

The development of fire‐safety measures for high‐speed passenger trains has been focused on preventing fire initiation or delaying fire growth and spread through small‐scale tests of the materials used in trains. However, new fire‐safety approaches for trains consider a systemic approach. This approach considers numerous global factors that influence fire dynamics, such as the influence of vehicle design, selection of materials, and active and passive protection systems installed. In the present paper, the results of small‐scale and full‐scale tests carried out on the new generation of high‐speed trains operating in Spain are presented. This rolling stock is classified as category B according to the Technical Specification for Interoperability and Operation Category 3 according to EN 45545–1. The results confirmed good fire behaviour using both approaches (small and full‐scale tests). Additionally, several analyses have been performed, including an analysis of the quality of materials used for making different components of the passenger compartment and the influence of ignition source position on fire development. Copyright © 2013 John Wiley & Sons, Ltd.     

Influence of gypsum board type (X or C) on real fire performance of partition assemblies

This paper compares the responses of wall‐size partition assemblies, composed of either type X or type C gypsum wallboard panels over steel studs, when each was exposed to an intense room fire. The exposures lasted from the time of ignition to beyond flashover. Heat flux gauges provided time histories of the energy incident on the partitions, while thermocouples provided data on the propagation of heat through the partitions and on the progress toward perforation. Visual and infrared cameras were used to image partition behaviour during the fire exposure. Contraction of the seams of the two types of assemblies occurred under similar thermal conditions on the unexposed surface. However, there were noticeable differences in cracking behaviour. Reduced scale experiments were performed in conjunction with the real‐scale fire tests to provide insight into the contraction and cracking behaviour of the different gypsum board types. Results obtained from these experiments are discussed. Copyright © 2006 John Wiley & Sons, Ltd.     

Vertical flame spread on charring materials at different ambient temperatures

A new flame spread apparatus for the measurement of flame spread rates at different ambient temperatures is presented. A 2‐m long sample is pre‐heated with air to the desired temperature and ignited from its lower end with a small propane burner. The flame spread is traced with thermocouples in contact with the sample surface. The features and function of the new apparatus are described, as well as series of vertical flame spread experiments on cylindrical birch rods and electrical cables made of polyvinylchloride (PVC) and flame retardant non‐corrosive (FRNC) materials. Vertical flame spread rates 6–62 mm/s (temperature range 22–271 °C) were determined for birch samples, 3–24 mm/s (22–190 °C) for PVC cable samples, and 0–4 mm/s (22–293 °C) for FRNC cable samples. Small‐scale experiments with thermogravimetric analysis and cone calorimeter were performed to characterize the sample materials in terms of their thermal and fire behaviour. Copyright © 2012 John Wiley & Sons, Ltd.     

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.     

A two‐step method for predicting time to flashover in room corner test fires using cone calorimeter data

A method to predict time to flashover in ISO 9705 room corner fire tests based on cone calorimeter data is proposed in this paper. The method involves classification of materials and estimation of time to flashover as two steps in sequence. In the first step, the investigated material is classified into discriminating material groups. In the second step, the time to flashover is calculated with a derived formula for the corresponding material group, which contains material density, time to ignition and heat release rate collected from small‐scale experiments. Compared with two existing models, the proposed method has improved the prediction precisions in both the time to flashover and classification of material categories for a wide range of materials. Copyright © 2012 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.     

Sub‐micrometre coatings as an infrared mirror: A new route to flame retardancy

Most of the polymeric materials used are easy to ignite and show extensive flame spread along their surfaces. Apart from extensive heat release rates, their short time to ignition (t_ig), in particular, is a key fire hazard. Preventing ignition eliminates fire hazards completely. Protection layers that shift t_ig by more than an order of magnitude are powerful flame retardancy approaches presenting an alternative to the usual flame retardancy concepts. Coatings are proposed that consist of a three‐layer system to ensure adhesion to the substrate, acting as an infrared (IR) mirror and protecting against oxidation. The IR‐mirror layer stack is realised by physical vapour deposition in the sub‐micrometre (<1 µm) range, reducing heat absorption by up to an order of magnitude. Not only is the ease of ignition diminished (t_ig is increased by several minutes), the flame spread and fire growth indices are also remarkably reduced to as little as 1/10 of the values of the uncoated polymers open for further optimization. Sub‐micrometre thin IR‐mirror coatings yielding surface absorptivity <0.1 are proposed as a novel and innovative flame retardancy approach. Copyright © 2011 John Wiley & Sons, Ltd.     

A study of fire performance of textile membranes used as building components

The advantages of textile materials as building components include low weight, and in the case of textile membranes, the advantages include translucency and architectural possibilities. A common disadvantage, however, is the fire property of textile materials, which highlights the importance of fire safety assessments for building application of such materials. The work presented in this paper was conducted within the European project contex‐T, ‘Textile Architecture – Textile Structures and Buildings of the Future’. This paper presents the results of reaction‐to‐fire tests required for European Standard (EN) 13501–1 classification conducted with a number of textile membranes. The classification results are compared for a selection of these membranes with the information gained from a large‐scale reference test that was designed within the project. The reference test was based on the International Organization for Standardization (ISO) 9705 room test. It was seen that the reference test could separate the performance of the different types of membranes investigated and the repeatability of duplicate tests performed was acceptable. However, the classification of the materials by test results from the Single Burning Item (SBI) test (EN 13823) and the small flame test (EN ISO 11925–2) did not reflect the performance of the membranes in the large‐scale test properly in all aspects important for fire safety. Most significantly, the ‘burn‐through’ and the associated opening of a hole in the polyvinyl chloride/polyester membranes tested ventilated the hot smoke gases out of the reference room that resulted in limited flame spread and heat production. This mechanism is not modelled correctly by the SBI test, which leads to a discrepancy between classification and large‐scale behaviour. Copyright © 2011 John Wiley & Sons, Ltd.     

Analysis of work on smoke component yields from room‐scale fire tests

Smoke Component Yields from Room‐Scale Fire Tests (NIST Technical Note TN 1453) has recently been published. This was expected to be an important work in developing concentrations and yields of toxicants that could be used for evaluating the usefulness of small scale smoke toxicity apparatuses (or fire models) for use in the prediction of the toxicity of materials and products in real fires. However, the work has a number of uncertainties that limit its potential for use as a reference. There are three major problems with this work. First, the post‐flashover concentrations of CO are too low (as recognized by the authors who recommend that this part of the data not be used). Second, the post‐flashover concentrations of the main toxicants measured (HCN and HC1) were much higher than found in most studies. Third, the precision of the data was inadequate. The consequence of the first two issues is that the work seriously overestimates the toxicological importance of gases known to have only minor effects in post‐flashover fires, such as HCN and HCl. The very low concentrations of toxicants measured at pre‐flashover conditions might have a value not discussed by the authors: an indication that pre‐flashover fires of the type conducted here do not generate extremely toxic atmospheres. Accordingly, the report does not provide reliable characteristic room scale combustion gas data that can be used for validating small‐scale furnaces. Copyright © 2005 John Wiley & Sons, Ltd.