Determination of critical heat transfer for the prediction of materials damages during a flame engulfment test

The personal protective equipment of workers exposed to heat can consist of materials with a relatively low melting point of approximately 250°C (membranes, zippers, and underwear). In particular, users of heat protective clothing (such as volunteer firefighters or industrial workers) are often consider using functional sports underwear for an optimized sweat transport and lower heat stress. However, in an emergency situation (flame engulfment), this kind of clothing can be potentially dangerous because of its low melting temperature. In this study, we investigated the critical heat transfer needed to melt synthetic underwear worn under heat protective clothing and developed a model to predict possible damage to material layers exposed to a flame engulfment condition. The fire protection properties of four clothing systems with varying layer structures were assessed. These combinations were tested on an instrumented manikin according to ISO 13506 (flame engulfment test). The thickness and thermal resistance of the individual garments were measured in order to examine the influence of each parameter on the performance of the complete clothing combination. The measurements showed that synthetic polyester underwear worn underneath heat protective clothing can withstand a 4s flame engulfment exposure without damage when the outer layer has an adequate thermal resistance. By using a simple heat transfer model, we could define a ‘critical thermal resistance’ as the thermal resistance of the outer layer required to prevent the melting of the underwear material. Copyright © 2016 John Wiley & Sons, Ltd.     

Thermal sensor performance and fire characterisation during short duration engulfment tests

A small-scale reproduction of the ISO 13506-1 thermal manikin was constructed to enable the assessment of manikin sensor performance, the partitioning of energy, and the variability of the fire generated during short duration heat and flame engulfment tests. The cylindrical test apparatus simultaneously housed four total heat flux (THF) sensors, one radiant heat flux sensor, and three manikin sensors. Calibrated manikin sensors were provided by nine laboratories and were categorised as buried thermocouple, copper-based, or surface-mounted thermocouple sensors. The test apparatus was exposed to fire generated by four propane torches for three exposure durations. All sensors presented similar profiles in net heat flux over time, which could be divided into four distinct phases: transient increase, pseudo-steady state, transient decrease, and post-exposure. Over pseudo-steady state, the mean THF over all exposure durations was 88 ± 8 kW/m², and the ratio of convective to radiant energy was approximately 50:50, but highly variable. For a 4-second exposure, manikin sensors from five laboratories had a bias in heat flux greater than ± 5% during pseudo-steady state when compared with the THF sensors. This bias can primarily be attributed to the sensitivity of the manikin sensors to convective heat or heat loss due to sensor design.     

Investigation and correlation of manikin and bench‐scale fire testing of clothing systems

The US Army currently has five flame/thermal protective clothing systems to provide protection for soldiers against fire hazards. The protective performance of these clothing systems against burn injuries was investigated in full‐scale manikin tests. The protective performance of fabric layers of these clothing systems was also examined in bench‐scale tests. In addition, air gap thicknesses and distributions of the five clothing systems were determined by using a three‐dimensional laser scanning technique. In this paper, test conditions of the manikin and bench‐scale tests are compared, and the test results are correlated in light of the air gap measurements. The behavior of individual sensors on the manikin with similar test conditions to those of bench‐scale tests are compared with the bench‐scale tests. It is found that if the air gap distribution of a clothing system is known, bench‐scale tests could provide useful information for full‐scale performance, especially bench‐scale tests with zero air gap measurements. Published in 2002 by John Wiley & Sons, Ltd.     

甲纶消防员灭火防护服热防护性能研究

采用符合XF 10—2014《消防员灭火防护服》标准的甲纶四层面料与芳纶四层面料,测试其组合的热防护系数(TPP值);用同样的面料制作灭火防护服,并通过假人燃烧实验对比甲纶灭火防护服与芳纶灭火防护服的整体热防护性能.结果表明:甲纶防护服热防护系数不及芳纶灭火防护服,但整体热防护性能远超现行芳纶灭火防护服,甲纶灭火防护服...     

Investigation of air gaps entrapped in protective clothing systems

Air gaps entrapped in protective clothing are known as one of the major factors affecting heat transfer through multiple layers of flexible clothing fabrics. The identification and quantification of the air gaps are two aspects of a multidisciplinary research effort directed toward improving the flame/thermal protective performance of the clothing. Today's three‐dimensional (3‐D) whole body digitizers, which provide accurate representations of the surface of the human body, can be a novel means for visualizing and quantifying the air gaps between the wearer and his clothing. In this paper we discuss how images from a 3‐D whole body digitizer are used to determine local and global distributions of air gaps and the quantification of air gap sizes in single and multilayer clothing systems dressed on a thermal manikin. Examples are given that show concordance between air gap distributions and burn patterns obtained from full‐scale manikin fire tests. We finish with a discussion of the application of air gap information to bench‐scale testing to improve the protective performance of current flame/thermal protective clothing. Copyright © 2002 John Wiley & Sons, Ltd.     

Synthesize and Characterization of Flame Retardant Copolyesters PET/Phosphorus Compound

The aim of this study was to achieve a fiber‐grade poly(ethylene terephthalate) (PET) with flame retardancy properties. Flame retardant copolyesters based on ethylene glycol, terephthalic acid, and 3‐(hydroxyphenyl phosphinyl) propionic acid (HPP), as a flame retardant comonomer, were synthesized in presence of antimony trioxide catalyst at laboratory and semi‐industrial scales. At first, copolyesters with the lowest amount of flame retardant comonomer were synthesized at laboratory scale in a one‐pot reactor setup. In the second stage, flame retardant PET was synthesized in semi‐industrial pilot with HPP (PET‐HPP). The obtained copolyesters demonstrated almost identical intrinsic viscosities and other characteristics such as PET. Fourier transform infrared spectroscopy (FTIR), 1H‐NMR spectroscopy, and RMS test were performed. Flame retardancies were evaluated by a limiting oxygen index (LOI) test. The results indicated that the presence of FR significantly improved the flame retardancy and thermal stability of PET‐HPP. LOI values increased from 28% (PET) to 33 (PET‐HPP) (at laboratory scale) and 44% (at semi‐industrial scale). Differential scanning calorimetry analysis showed that the HPP polyester chain had a higher flexibility compared to PET, due to lower glass transition temperature. The effect of adding FR with regard to the thermal stability of PET‐HPP was investigated via thermogravimetric analysis. The physical properties of both the polymers are similar and suitable for textile application. J. VINYL ADDIT. TECHNOL., 25:262–270, 2019. © 2018 Society of Plastics Engineers     

Simulating the thermal response of the flame manikin with different materials exposed to flash fire by CFD

To investigate the differences of thermal response between heat flux sensors and human skin on the flame manikin, a three‐dimensional heat transfer model was developed and validated by the flame manikin system. The initial temperature of the model with sensor material was set to 300 K, and the model with skin material was set as the real condition. Simulated results validated the effectiveness of heat flux measured by the sensor. The incident heat flux through the measured surface was influenced by the different emissivity of the human skin and experimental sensors. Significant difference was found for the temperature response of these two kinds of materials within 4‐s fire exposure. The heat flux measured by sensor or the simulated results with actual human skin parameters could be used as the input boundary condition of the skin heat transfer model for Henriques's skin burn prediction. It is necessary to study the actual skin thermal response by experiments, where the 3D model established in this study could be used as the supplementary means for skin simulant sensor development. These findings will also be adopted in our following study of skin burn prediction module in the 3D full‐scale simulation platform. Copyright © 2016 John Wiley & Sons, Ltd.     

Thermal stabilities and flame retardancies of phloroglucinol‐based organo phosphates when applied to polycarbonate

A series of organo phosphorus flame retardants (FRs) based on aromatic phosphate and cyclic phosphate were synthesized in an attempt to develop an efficient FR for polycarbonate. Their successful synthesis was confirmed by FT‐IR and ¹ H and ³¹P NMR. Their thermal stability and flame retarding efficiency as a single‐component additive were investigated and compared with the commercial FR, resorcinol bis(diphenyl phosphate). The thermogravimetric analysis results revealed that the aromatic phosphate synthesized in this study, phloroglucinol diphenyl phosphate (PDP), shows a higher thermal degradation temperature and better flame retardancy even though it has a lower P content than cyclic phosphate‐based FRs. The flame retarding efficiency was evaluated by the UL‐94 test method. The V‐0 rating was achieved at a PDP loading of 2 wt% in polycarbonate in the presence of an anti‐dripping agent (1 wt%), which is better than that of resorcinol bis(diphenyl phosphate) and cyclic phosphate‐based FRs. The high thermal stability and P–OH generation tendency is responsible for the better flame‐retarding performance of PDP. The degradation path of PDP is also discussed. Copyright © 2012 John Wiley & Sons, Ltd.     

Standards for the fire hazard of clothing: The Australian experience

The Australian Children's Nightwear Standards have been accepted as the basis of legislation in all States of Australia and by the Commonwealth Government. The standards are based on the philosophy that garment design as well as combustion characteristics of the material is an important consideration in assessing the fire hazard of nightwear. Using this approach a classification system has been devised which place children's nightwear into three categories of potential fire hazard. If a garment cannot be classified then it cannot be legally sold in Australia. The combustion characteristics tested are ease of ignition, rate of flame propagation and surface burn properties. For classification all materials used for children's nightwear must pass the latter test. The design of the standard test methods, criteria for classification and the concepts of safe design were developed by collection data from burns accidents and burnt clothing from accident victims from the burns research unit of a large children's hospital and by the study of the burning behavior of clothing on a manikin. The combustion criteria are not so stringent as to require the use of inherently flame resist materials or the use of flame retardant finishes. This approach in combination with safe design criterial enable commercially available textiles to meet the legislative requirements for children's nightwear. This mean that the nightwear standards are inexpensive to attain and do not require a sophisticated textile technology. A consumer labeling system has been designed to describe the three categories but yet there is no evidence to suggest that this had had any effect in reducing the number of burns accidents—consumers apparently regrading safe nightwear as a low priority. An inconsistent aspect of the calssification system is the incorporation into the standards in 1977 of criteria to prevent the classification of cotton flannelette nightdresses and the incorporation of arbitrary requirements for other nightdress containing cotton. These inconsistencies have been caused fundamentally by a problem which continues to bedevil the writing of good standards in Australia—that is, the lack of nationwide statistics on burns accidents.     

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.     

Assessing the reaction to fire of cables by a new bench‐scale method

The recently approved EU Construction Products Regulation (CPR) applies to cables as construction products. The difficulty of predicting the fire performance of cables with respect to propagation of flame and contribution to fire hazards is well known. The new standard EN 50399 describes a full‐scale test method for the classification of vertically mounted bunched cables according to CPR. Consideration of the material, time, and thus cost requires an alternative bench‐scale fire test, which finds strong demand for screening and development purposes. The development of such a bench‐scale fire test to assess the fire performance of multiple vertically mounted cables is described. A practical module for the cone calorimeter is proposed, simulating the fire scenario of the EN 50399 on the bench scale. The efficacy of this module in predicting full‐scale CPR test results is shown for a set of 20 different optical cables. Key properties such as peak heat release rate (PHRR), fire growth rate (FIGRA), and flame spread are linked to each other by factors of around 5. In a case study, the bench‐scale test designed was used to investigate the influence of the main components on the fire behaviour of a complex optical cable. Copyright © 2016 John Wiley & Sons, Ltd.     

Numerical Investigation of Flow Patterns and Concentration Profiles in Y‐Mixers

The fluid flow patterns and associated concentration fields in Y‐mixers are investigated using lattice Boltzmann method‐based models. The focus lies on the impact of the mixing angle on the flow and concentration fields, with the mixing angle varying between acute (θ = 10°) and obtuse (θ = 130°) angles. Residence time distributions are determined to study the effect of the angles on the mixing and velocity patterns, in particular, different flow regimes, i.e., stratified laminar, vortex, and engulfment flow. The results from the simulations are validated with literature data and found to be in good agreement. Maximum mixing occurs in the 100° obtuse‐angle Y‐mixer, attributed to the extensive engulfment of flows in the mixing channel.     

Current Japanese standards for flammability tests on electric cables

This paper outlines the flammability test methods and requirements for electric cables specified in some Japanese standards. Only two different methods of a small-scale flame test as specified in Clause 28 of JIS C 3005 are applied to electric cables for general use, and whether or not the flammability test should be conducted and which method should be adopted depends on the type of cables, both of which are specified in each separate standard. Cables for electrical equipment of ships have to pass another small-scale flame test as prescribed in Section 6.7 of JIS C 3410. A flame test method for flame-retardant telecommunication cables has been introduced in JIS C 3521. This specifies a vertical open tray flame test on grouped cables, almost in accordance with IEEE Standard 383. In addition to the method for a vertical open tray flame test, one for a vertical closed duct flame test on grouped cables is also specified in a Japanese Cable Makers' Association Standard, i.e. JCS 366. Some flame-retardance requirements for electric cables in Japan are listed and discussed.     

Assessment of draft ISO radiant panel spread-of-flame test

A versatile radiant panel apparatus for studying flame propagation in materials used as interior finishes on floors, walls and ceilings is described. Comparative trials with this apparatus and other tests based on relatively very small sources of heat were made on a wide variety of floorcoverings. The results showed that fibre composition and specimen orientation have a marked effect on flame spread. Materials which gave favourable (low flame spread) results in the panel test also gave favourable results in the small heat source tests. On the other hand, some materials which gave favourable results in the small heat source tests gave unfavourable results in the panel test. It was concluded that although small heat source tests will continue to play an important role in flammability testing, the radiant panel test gives an additional assurance of the flame spread resistance of materials in general and should be strongly recommended for materials intended for high risk areas. The effects on flame spread in the panel test of various factors concerned for materials intended for high risk areas. The effects on flame spread in the panel test of various factors concerned with the structure and conditions of test specimens and the apparatus are discussed. A small modification of the radiant panel apparatus is described which enables it to be temporarily altered to simulate a standard French radiant panel test.     

A mechanistic method for scrutinising LIFT ignition data

The lateral ignition and flame spread test (LIFT) standard (ASTM E 1321‐97a) requires the Thermal Response correlation to be scrutinized for data points that violate the zero heat loss requirement, but the standard gives no guidance on how this should be done. The fundamentals of linear regression were reviewed and an unbiased and mechanistic algorithm for scrutinising LIFT ignition data without human intervention was developed. The algorithm produced reasonable results compared with human interpretation of exemplar test data taken from the literature. Copyright © 2010 John Wiley & Sons, Ltd.     

Combustion behavior and application of polyolefin‐based floor sheet laminated with Nylon‐6/clay nanocomposites film

Nanocomposites are potential materials that can be used to improve the flame resistance of polymers without the need for halogen‐based flame retardants. However, the nanocomposites cannot be used as the only raw material to produce final products as they are too expensive compared with low‐cost commodity plastics. Therefore, some types of polyolefin‐based floor sheet laminated with nanocomposites film were prepared for the cone calorimetric study to determine the suitable nanocomposites laminated structure for flame resistance. This study found that the polyolefin‐based floor sheet laminated with 200 µm Nylon‐6/montmorillonite nanocomposites film on the surface can reduce the HRR _max and the S significantly; other types of nanocomposites film‐laminated floor sheet were not able to reduce their flame resistance in comparison with the normal Nylon‐6 film‐laminated floor sheet. Meanwhile, based on the gas barrier performance, the higher aspect ratio of clay is assumed to contribute to the higher flame resistance of nanocomposites. Thus, the polyolefin‐based floor sheet laminated with Nylon‐6/sericite nanocomposites film on the surface was also prepared and examined in the cone calorimetric study. However, the Nylon‐6/sericite nanocomposites film surface‐laminated floor sheet did not cause a significant reduction in the HRR _max and S compared with the Nylon‐6/montmorillonite nanocomposites film surface‐laminated floor sheet. The grade determined according to the standard fire test and the mechanical properties of the Nylon‐6/montmorillonite nanocomposites film surface‐laminated floor sheet satisfied the requirements for floor sheets for Japanese railway vehicles. Copyright © 2010 John Wiley & Sons, Ltd.     

Preparation and characterization of new flame retardant polyurethane composite and nanocomposite

In this work, a new flame retardant additive [2‐phenyl‐1,3,2 oxazaphospholidine 2‐oxide (POPO)] containing phosphorus and nitrogen is synthesized using phenyl phosphonic dichloride, ethanol amine, and copper (II) chloride, as catalyst. POPO is characterized by ¹H‐NMR, ¹³C‐NMR, and ³¹P‐NMR and used as additive in polyurethane composites. Moreover, two commercial flame retardant additives [tricalcium diphosphate and hexabromocyclododecane (HBCD)] as well as nanoclay are used to compare flame retardancy of the synthesized additive. Limited oxygen index (LOI) and time burning (flammability test) of polyurethane composites and nanocomposites are evaluated. The results of the LOI test demonstrate that POPO is an excellent flame retardant additive and can be used to improve flame retardancy of polyurethane composites. In addition, increasing the additive content leads to an improvement of the flame retardancy of the samples. The LOI results show, however, that POPO is a good flame retardant, but the high synthesis cost of this flame retardant is a major disadvantage. Thermogravimetric analysis results show that using POPO in polyurethane matrices leads to low thermal stability and high char residue. Moreover, the nanocomposite has better thermal stability than the other samples. Scanning electron microscope micrographs have been used to evaluate the char residue of the samples. These micrographs indicate that POPO is an intumescent flame retardant and HBCD follows a nonintumescent mechanism. Exfoliated/intercalated structures have been shown for nanocomposites by transmission electron microscope. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Mathematical modelling of fire development in cable installations

In 1996 DG XII of the European Commission (Research and Development) approved a 3 year project on the fire performance of electrical cables. Within this FIPEC project, a major part of the work involved correlation and mathematical modelling of flame spread and heat release rate in cable installations. The FIPEC project has developed different levels of testing ranging from a small‐scale, cone calorimeter test procedures developed for cables and materials, a full‐scale‐test procedure based on the IEC 60332‐3, but utilizing HRR and SPR measurements, and a real scale test conducted on model cable installations. Links through statistical correlations and mathematical fire modelling between these levels were investigated and the findings are presented in this paper. These links could form the scientific foundations for standards upon which fire performance measurements can be based and for new fire engineering techniques within fire performance based codes. Between each testing level correlation, numerical and mathematical models were performed. All of the models were based on the cone calorimeter test method. The complexity of the models varied from correlation models to advanced physical pyrolysis models which can be used in CFD codes. The results will allow advanced prediction of cable fires in the future. Also a bench mark was established for the prediction of cable performance by means of data obtained from the constituent materials. Copyright © 2002 John Wiley & Sons, Ltd.