A cone calorimeter for controlled-atmosphere studies

Many fires occur in ambient atmospheric conditions. To investigate certain types of fires, however, it is necessary to consider combustion where the oxidizer is not 21% oxygen/79% nitrogen. The Cone Calorimeter (ASTM E 1354, ISO DIS 5660) has recently become the tool of choice for studying the fire properties of products and materials. Its standard use involves burning specimens with room air being drawn in for combustion. To facilitate studying fires involving different atmospheres, a special version of the Cone Calorimeter was designed. This unit allows controlled combustion atmospheres to be created by the use of bottled or piped gases. To make such operation feasible, a large number of design details of the standard calorimeter had to be modified. This paper describes the background for these changes and provides an explanation of how the controlled-atmospheres unit is operated.     

Flammability studies of sodium thiosulphate or metabisulphite impregnated wood using cone calorimeter

Spruce wood boards impregnated with Na₂S₂O₃ or Na₂S₂O₅ were studied with the cone calorimeter. The presence of Na₂S₂O₃ lowered the average heat release rate in comparison to untreated material. The total amounts of CO and CO₂ production were reduced by the treatment and also the specific extinction area and mass loss rate decreased. Washing of the salt from the material with water caused partial loss of the properties. Addition of the second impregnation step using acids (HCOOH, H₃BO₃ or H₃PO₄) resulted in the fixation of the sulphur in wood, but gave not the results of single‐step modification for thiosulphate. With Na₂S₂O₅ and without acid, the CO and time‐to‐ignition values were higher and average heat release rate smaller in comparison to unmodified material. Combined one step Na₂S₂O₅/H₃BO₃ treatment lowered the CO, CO₂ and specific extinction area values in comparison to the modification with Na₂S₂O₅, similarly like it was observed for Na₂S₂O₃/H₃BO₃ two‐step‐treatment. According to time‐to‐ignition values, Na₂S₂O₅ alone at 5% addition is a better flame retardant than Na₂S₂O₃ at 7%, but the effect is diminished at 10% amount or presence of acids. The total smoke release curves showed decrease due to modification in both phases of the process. Introduction of water washing as well as the acid treatment further lowered the values. The best results were achieved with 15% Na₂S₂O₃–2% H₃PO₄–H₂O system. According to the total smoke release curve the specimen produced more than five times smaller amount of smoke than untreated material in the first phase of the process. It seams that the concentration of Na₂S₂O₅ is less affecting the properties than the synergistic effect of the Na₂S₂O₃ or Na₂S₂O₅/H₃BO₃ system. Although the level of smoke is low, the presence of elemental sulphur causes smaller times‐to‐ignition than on starting material. Copyright © 2006 John Wiley & Sons, Ltd.     

BDMC interlaboratory cone calorimeter test programme

In the spring of 1997, seven companies and industry associations from the USA and Canada decided to sponsor the cone calorimeter interlaboratory test programme. Reproducibility and repeatability were determined for the scalar variables measured in the cone calorimeter (ASTM E1354) according to the protocol developed by the Board for the Coordination of the Model Codes. The main requirement of the protocol was that the sample irradiance should be 75 kW/m². The purpose of the project was to assist the model building code organizations, NFPA and various other groups in the development of a system to determine degrees of combustibility of building materials. Three US and one Canadian laboratory agreed to conduct tests on 16 materials. The results of this round robin show that the cone calorimeter, following the Board for the Coordination of the Model Codes protocol, can provide precision similar to that cited in the current cone calorimeter standards. It is recommended that further improvements of the standards are pursued and provisions are made to improve the quality of operation of the cone calorimeter in commercial laboratories to maintain and possibly improve its repeatability and reproducibility. Copyright © 2002 John Wiley & Sons, Ltd.     

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.     

Calibration of flow rate in cone calorimeter tests

The cone calorimeter is one of the major fire tests. The measurement method is based on the evaluation of mass flow and oxygen concentration of fire effluents to calculate heat release rate. Different studies highlighted that the governing parameter for uncertainty at important values of heat release rate was the characteristic constant of an orifice plate used to measure mass flow (C‐factor). This parameter is usually determined each testing day by oxygen consumption calorimetry with a reference methane burner. This publication presents a calibration method for volumetric flow rate without using orifice plate and then an extension to C‐factor determination without methane burner and calorimetry. The uncertainty calculation applied to a real example highlights the fact that the method is suitable to respect tolerance of standardized test conditions for both parameters. Copyright © 2013 John Wiley & Sons, Ltd.     

Investigation of polymeric materials using the cone calorimeter

The use of polymeric materials in building or construction applications is steadily increasing. Therefore, the potential for these materials to be exposed to fire is also increased. The understanding of the pyrolysis characteristics of these materials is thus a necessity. There are many standard tests used to evaluate materials. Unfortunately, the correlation between these tests and large scale fire is less than desirable. A new bench scale rate of heat release apparatus, the Cone Calorimeter, is now being used more frequently in pyrolysis testing of polymeric materials. This apparatus has been shown to correlate much better between room scale testing and large scale fire testing. The cone Calorimeter provides a pyrolysis profile of a material under ambient oxygen conditions. Characteristics such as ignition time, total heat release, maximum rate of heat release, mass loss during pyrolysis, CO₂, CO, and smoke production are determined. In this work several almost neat polymers are examined and the general pyrolysis characteristics of these polymers are discussed. The objective of this work is to provide information of basic polymeric pyrolysis properties of these materials. Variations in the material, i.e., molecular weight, polydispersity, and residual catalysis, along with changes in testing procedures, can have dramatic effects on results. Obviously the addition of flame retardant and flame retardant packages to any of these materials will have dramatic effects on results.     

Testing of mattress composites in the cone calorimeter

An investigation of cone calorimeter test procedures was performed using two types of mattress composites with various specimen preparations and equipment configurations. The objective was to discover suitable procedures for testing mattress composites. Concurrent with this work a much larger and more sophisticated project known as CBUF was underway in Europe. One of CBUF's secondary objectives was to provide an appropriate test protocol for testing upholstered furniture composites, including mattresses. Most of the CBUF protocol was available at the time of this study and a modified form of the specimen preparation technique was used in this investigation. Preliminary tests found unacceptable test performance with some configurations. Subsequent testing examined variations of the established test protocols and other test procedures. The data sample was small, but observations of the data indicate trends that might be attributable to the use of the different procedures. Significantly it was determined that the edge frame used to hold specimens in place during the test does affect the test results. A modified CBUF protocol proved to be the best procedure, but it requires extensive experience with the CBUF specimen preparation method in order to be able to produce satisfactory specimens. © 1997 by John Wiley & Sons, Ltd.     

Combustion behavior characterization of major crops through cone calorimeter

Induced by extremely inflammable characteristic, fire accidents worldwide of crops frequently occur and give rise to loss of life and personal injury. Given this problem, combustion behavior characterization of four major crops was investigated by cone calorimeter. Results confirmed the less quantity of crops needed longer time to be ignited. Meanwhile, the linear relation between the inverse square of time to ignition and heat flux of crops was found. For heat release rate (HRR), it was demonstrated that more quantity of crops prolonged the heat release process. For instance, with heat flux of 50 kW/m², HRR values of 100 and 50 g soybean at 400 seconds were 212 and 40 kW/m². Besides, peak values of HRR (PHRR) were close with different mass, especially for corn. Interestingly, compared to less quantity, more quantity crops were harder to be ignited at same heat flux. In addition to soybean, PHRR and total heat release (THR) of crops was gradually increased with the increasing heat flux. Meanwhile, THR values of 100 g crops were lower than double THR of 50 g crops. The investigation of combustion behavior characteristic could guide the safety storage of crops, thus avoiding the occurrence of crops fire hazards.     

Development of a controlled‐atmosphere cone calorimeter

A controlled‐atmosphere cone calorimeter has been developed that overcomes many of the shortcomings of previously developed units. The new apparatus is a fully sealed ‘blow‐through’ system, which provides a full‐size chamber in which the combustion process can occur. Oxygen concentrations from 0%–20.95% are achieved while maintaining the required configuration and flow rates to meet standard cone calorimeter testing requirements. The apparatus was developed in order to obtain data on the burning of materials at reduced oxygen levels for modelling purposes. It is now being used in pyrolysis studies assisting in the determination of fundamental material flammability properties. Copyright © CSIRO Australia 2000     

Influence of decreased sample size on cone calorimeter results

Cone calorimeter sample size sensitivity and the influence of sample size on the results were studied in order to investigate the possibility to use smaller samples than prescribed by the standard. The influence of the position of the sample on the sample holder of the decreased samples was also studied. Samples of birch plywood, industrial two‐component polyurethane adhesive and polypropylene wax were tested. The results from standard size sample experiments, 100 cm ², and decreased sample size, 50 and 25 cm², were compared, in order to investigate the sample size influence on the results. The experiments were performed using an external heat flux of 50kW/ m². The results show differences between the sample types. The measured heat release rates for plywood and polyurethane adhesive indicate that the sample size is possible to down‐scale, while the polypropylene wax results show the opposite. All sample types and sizes show constant results for the effective heat of combustion, indicating down‐scalability. For in‐house testing and screening of materials, downscaling can be used for most sample types. However, results from experiments carried out with decreased sample size should not be compared to results from experiments executed according to the standard procedure. Copyright © 2011 John Wiley & Sons, Ltd.     

Evaluation of passenger train car materials in the cone calorimeter

Recent advances in fire test methods and hazard analysis techniques make it useful to re‐examine passenger train fire safety requirements. The use of test methods based on heat release rate (HRR), incorporated with fire modelling and hazard analysis, could permit the assessment of potential hazards under realistic fire conditions. The results of research directed at the evaluation of passenger train car interior materials in the cone calorimeter are presented. These measurements provide data necessary for fire modelling as well as quantitative data that can be used to evaluate the performance of component materials and assemblies. The cone calorimeter test data were also compared with test data resulting from individual bench‐test methods specified in the FRA fire safety guidelines. The majority of the tested materials which meet the current FRA guidelines show comparable performance in the cone calorimeter. Copyright © 1999 John Wiley & Sons, Ltd.     

用锥形量热仪研究无卤阻燃聚丙烯体系燃烧性

采用Mg(OH)2作为无卤阻燃剂对聚丙烯(PP)进行了阻燃改性.结果表明,随Mg(OH)2加人,体系的冲击强度和断裂伸长率有所下降,热变形温度、弯曲强度和氧指数有所提高,极限氧指数达到29%.在50 kW/m2热辐照条件下,利用锥形量热仪研究了Mg(OH)2阻燃聚丙烯体系的燃烧性,Mg(OH)2能明显降低PP的热释放速率(HRR)、有效燃烧热(EHC)和质量损失速率(MLR).     

A simple calorimeter for hydration studies

A semi-adiabatic calorimeter was designed in order to study hydration reactions of cements and cement constituents. Its construction is inexpensive and uncomplicated and it is easily operated. The sensitivity is less than 1 cal/gm-hr and the read-out can be detected in less than one minute. The reproducibility of the results has been found to be very good.     

Mortars containing wood-based fibres under thermal exposure using cone calorimeter heating

The behaviour of concrete structures under fire can be improved by adding fibers. However, relatively little is known of the details of the possible beneficial features of the fibre addition. The aim of this study was to compare the effects of different wood-based fibres on the thermal properties of a standard laboratory cement mortar at conditions of a developing fire. The cone calorimeter heating method was used, and the sample thickness and heat flux were varied (25 mm or 50 mm, 25 kWm^?2 or 50 kWm^?2) to compare test conditions. The fibres comprised chemical pulp, chemi-thermomechanical pulp, recycled fibres and viscose fibres. The fibre content in the mortar was 0.15–0.5% by weight. Temperature and mass loos measurements of oven-dried specimens (moisture content <0.1%) showed no differences between different wood-based fibre mortars and plain mortar. With increasing moisture content (about 5%), however, the presence of fibres affected the release of moisture from the fibre mortar material. With rapid heating of mortars, which have a moisture content of about 5%, local pressures are easily built up. These pressures are mainly caused by free water vaporization. The rear surface temperature measurements indicate that in mortars containing wood-based fibres (0.15–0.5% by weight) the vaporization temperatures may be 20 –25% lower than in the reference mortar. Some effects on heat transfer can also be observed due to differences in water vaporization and movement processes.     

An exercise in obtaining flame radiation fraction from the cone calorimeter

The radiant fraction of the heat of combustion emitted by flames of burning fuels is an important quantity needed to predict the thermal radiation from pool fires to remote targets and as a local flame parameter in CFD models. Although there are data for radiant fraction of gas flames, there are little data for this parameter for burning solid materials. The sole source of these data is Archie Tewarson, who used the FMGlobal Fire Propagation Apparatus to compute the radiant fraction of the heat of combustion from energy losses associated with enthalpy flow and duct heat losses. This paper describes a similar approach to obtain the radiant fraction of the heat from flames of burning solids using the cone calorimeter. In the present work, the cone calorimeter is calibrated using a Meeker burner with a premixed methane/air flame that is small and blue and has minimum flame radiation. A heat loss correction factor due to thermal conductance from the duct to the ambient air is determined from the calibration by measuring the temperature of the combustion stream in the duct at the gas sampling location. That factor was found to be 13 ± 2 W/K by calibration compared with a theoretical estimate of 9.3 W/K. The effect of the heat capacity of the duct walls is accounted for by de‐convoluting the duct temperature history. The necessary measurements to compute the radiant fraction then become the heat release rate by oxygen consumption, the mass flow rate in the duct, and the gas temperature in the duct at the sampling location. Results were obtained for 15 polymers, eight of which could be compared with data for nominally similar materials obtained by Tewarson. In addition, results are found to be in good agreement with a correlation by Tewarson in terms of combustion efficiency. Copyright © 2016 John Wiley & Sons, Ltd.     

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.     

Characterization of highly under‐ventilated fires using the cone calorimeter

The cone calorimeter, originally designed with an ‘open configuration‘, may be used in combination with a closed‐combustion chamber in order to test specimens in oxygen‐depleted atmospheres (air vitiation effect) or in fuel‐rich combustion (ventilation effect). However, highly under‐ventilated conditions are not achievable, as a consequence of an overconsumption of oxygen due to the incomplete confinement of the flame and imperfections in the air tightness of the combustion volume. In this work, these issues were solved by lowering the combustion zone, in order to fit a 600 mm chimney on the top of the controlled‐atmosphere chamber, and further improving the sealing of the whole setup. n‐Heptane was used as a reference fuel, and its combustion properties were determined in under‐ventilated conditions. The yields of main combustion species correlated well with the global equivalence ratio, for values of Φ up to three. The use of a Fourier‐transform infrared spectrometer allowed further refinement of the total unburned‐fraction composition. The relative concentration of species like methane, ethylene, or acetylene was shown to be relatively constant over the range of under‐ventilated conditions. Copyright © 2015 John Wiley & Sons, Ltd.