Showing papers on "Cone calorimeter published in 1994"

The Assessment of Full-Scale Fire Hazards from Cone Calorimeter Data:

Abstract: SEVERAL INVESTIGATORS HAVE tried, with varying degrees of success, to predict the full-scale fire behavior of materials from bench-scale test methods. Babrauskas showed that full-scale furniture calorimeter peak heat release rates and combustion durations could be predicted, with a fair degree of accuracy, from the cone calorimeter for upholstered furniture and wall linings [1]. More recently Wickstrom and Goransson [2], Hirschler [3], Ostman and Nussbaum [4] and Hirschler and Poletti [5] have used the ratio of the time to ignition to the peak rate of heat release, TTI/pk RHR, to indicate the propensity to flashover. The rationale for using TTI/pk RHR as an indicator of flashover is that a short ignition time and a large peak rate of heat release are thought to be necessary requirements for flashover to occur. On this basis, the smaller the value of TTI/pk RHR, the greater the tendency for flashover to occur. Hirschler [6] ranks a number of plastic materials in just such an order. Babrauskas [1], in the original considerations on flashover, used the reciprocal of TTI/pk RHR to indicate the propensity to flashover. In his system, higher values of pk RHR/TTI are associated with a greater propensity to flashover. Either scale could be used to

Fire performance studies on glass-reinforced plastic laminates

Abstract: Polyester, epoxy and phenolic glass-reinforced laminates were compared in terms of their fire properties in the cone calorimeter. The presence of a gel coat on the polyester and epoxy products had some effect, mainly in the FR grades. The FR polyester with a brominated flame retardant showed a marked decrease in rate of heat release and in rate of smoke production. Aluminium hydroxide (commonly called alumina trihydrate of ATH) caused a significant delay in ignition time for the epoxy product and some reduction in rate of heat release but rate of smoke release was still relatively high. Phenolic laminates showed a long ignition time and relatively low rate of heat release (RHR). The peak RHR was further reduced by the presence of aluminium hydroxide and by changing the type of glass reinforcement. The influence of thickness was explored for a series of phenolic laminates in both cone calorimeter and the International Maritime Organization (IMO) surface flammability test. Ignition delay time was significantly affected and the cone calorimeter results showed that the shape of the RHR curve was also changed as the thickness increased. However, the heat release measurements in the IMO test were not sensitive enough to pick up the differences in this property. The type of substrate under the laminate significantly altered the burning rate but this may have been because they were not glued or mechanically fixed.

Flammability of GRP for use in ship superstructures

Abstract: The burning characteristics of glass-reinforced panels with an isophthalic polyester resin, the same resin with an inorganic flame retardant, two differing vinylester resins or a resole phenolic as the matrix were tested at a range of incident heat flux values using a cone calorimeter. The phenolic composite was superior at all levels showing a longer ignition time, reduced heat output, less contribution to a low-level sustained fire (25 kWm−2) and lower smoke yield.

Correlation between cone calorimeter data and time to flashover in the room fire test

Abstract: Correlations based on linear regressions between data as time to ignition and heat release in the cone calorimeter and time to flashover in the room fire test have been developed. They are a further development of an earlier approach which has been modified and extended to a wider range of surface linings. The correlations apply so far only to surface linings on both walls and ceilings. When the density of the linings as a simplified measure of the thermal inertia is included, the correlations are improved significantly. The new correlations are based on data readily available from the cone calorimeter test at one heat flux level, 50 kWm−2. The correlation coefficient for the basic relationship, including the density of the linings, is now 0.98 when applied to the 13 linings investigated earlier. This is slightly better than the previous study, in which the best correlation coefficient was 0.96. When applied to 28 linings, the correlation coefficient remains about the same (0.97). Very similar regression equations have been obtained when analysing only 13 products and all 28. This is a strong indication of the general predictive capacity of this approach. The inclusion of other data such as thickness of linings or mass loss during fire does not improve the correlation coefficients. The approach is quite straightforward and simple. However, it has provided a useful prediction which is also valid for an extended range of linings.

Fire-hazard assessment of extended-chain polyethylene and aramid composites by cone calorimetry

Abstract: A cone calorimeter is used to determine the fire performance of polymer composite materials containing combustible reinforcing fibres in addition to combustible matrix resins. Extended-chain polyethylene and aramid fibre-reinforced composites containing epoxy, vinylester and phenolic matrix resins are examined at various cone irradiances. Values for time to ignition, rate of heat release, effective heat of combustion, smoke density and evolved carbon monoxide and carbon dioxide are reported for the reinforcements, matrix resins and composites. The reinforcements have a significant effect on the fire-hazard properties of the composite materials. For the epoxy and vinylester composites, times to ignition reflect those of the component of higher ignitability. This was not the case for the aramid-reinforced phenolic composite, in which the resin surface layer hinders combustion of the fabric reinforcement. Resin and reinforcement contributions to the composite rate of heat release behaviour as a function of time are generally discernible.

Fibre mortar composites under fire conditions: effects of ageing and moisture content of specimens

Abstract: Two small scale test series were performed using the cone calorimeter heating method to detect any differences in the way various fibres affect the thermal properties of a standard mortar. The cone shaped heater of the cone calorimeter produces a uniform heat flux on the sample surface over an area of 100×100 mm2. The heat flux was adjusted to 50 kW m−2, which corresponds to the early stage of a fully developed fire. The total exposure also corresponds roughly to the ISO 834 time-temperature curve during the first 30 minutes. Short ageing of the specimens gave very clear differences in thermal properties between fibre mortars. However, no such differences were observed with oven dried samples. This shows the importance of carrying out tests in conditions as close as possible to the end use conditions of the material or product.

Fibre mortar composites in fire conditions

Abstract: A small-scale test series was carried out using the heating system (radiant exposure) of a cone calorimeter to detect any differences in the way different fibres affect the thermal properties of a standard mortar. The fibres were different polypropylene, polyacrylonitrile, aramide, carbon or steel. Fibres affect the release of moisture from the fibre mortar material. Local pressures caused by water vaporization due to rapid heating can be decreased by incorporating fibres. Fibres have a weak insulating effect. However, use of polyacrylonitrile fibres in mortar may increase the risk to spalling under rapid thermal exposure such as fire. The moisture level in specimens is highly significant for their thermal properties and hence their fire behavior.

Co/co2 Ratios In Fire

Abstract: The COICO, mol ratio has been used to estimate CO generation for hazard assessment in some room fire models. For better estimation of CO, more detailed usage of the COIC02 ratio and more experimental data on their values seem required. COICO, mol ratios in the literature, measured using small-scale apparatuses and in large-scale experiments, were reviewed. The ratios for different materials at different fire conditions were experimentally measured using an oxygen depletion OSU apparatus and cone calorimeter. COICO, mol ratios depended on fuel types and fire conditions, but for a type of fuel in one mode of combustion, the ratio was fairly stable. It is suggested to apply different COICO, values to each fuel block for each stage of combustion in a fire modelling to estimate the CO generation.

Corrosivity Test Methods for Polymeric Materials. Part 2- CNET Test Method:

Abstract: This is the second in a series of papers to investigate smoke corrosivity test methods published by the Polyolefins Fire Performance Council, a unit of The Society of the Plastics Industry, Inc. In the first paper, 24 polymeric materials were evaluated for smoke corrosion using the ASTM E05.21.70 proposed method for measuring the corrosive effect of smoke from the burning or thermal decomposition of materials and products with a radiant combustion/exposure apparatus. This paper presents results on the same 24 materials evaluated with the CNET corrosivity test method under consideration by ISO TC61/SC4/WG2 and IEC TC89/WG3. These commercially available polymeric materials cover a broad range of compositions used for wire and cable insulation and jacketing. The samples were decomposed in the CNET apparatus which contained a printed copper circuit board as the corrosion target. The target was held at a lower temperature than the chamber to facilitate the condensation of the combustion gases. After exposure to the condensed combustion gases for one hour, the resistance change of the target was measured and the Corrosivity Factor ''COR'' was calculated for each material. These results are discussed and compared with the results of the ASTM E05.21.70 method. To complete the review of corrosion test methods, studies are under way to evaluate the DIN 57 472 Acid Gas test method and the cone calorimeter corrosivity test method under review by the ASTM D09.21.04 using the same 24 materials.

Char Studies: Flame Retarded Polycarbonate/PET Blend

Abstract: Bromine and phosphorus were shown to be synergistic in flame retarding a polycarbonate/PET blend as measured by oxygen index. This synergy is enhanced when both elements are present in the same molecule. Cone calorimeter data confirm these observations. Chars were formed by py rolysis in the TGA apparatus, by burning at high oxygen concentration in the oxygen index apparatus and by forced combustion in the cone calorimeter. Chars formed from the polymer blend containing the brominated phosphate gave 40-50% more char by weight than when bromine, phosphorus or blends of the two were used. Analyses of the chars showed no bromine and considerable phosphorus. TGA and DSC studies suggest that the polycarbonate and the PET undergo transesterification during pyrolysis above 400°C and the brominated phosphate acts as a transesterification inhibitor or stabilizer. SEM of the chars showed a considerable difference. When the brominated phosphate was used the char had a fine porous structure and thick solid skin. The ...

Use Of Small-scale Test Data In Hazard Analysis

Abstract: This paper presents a concept of the use of small-scale test data as the basis of an analytical evaluation of the level of hazard involved in the use of a tested material. The scope of this paper is limited to analysis of the potential of ignition and fire growth involving the use of innovative materials as the skin of aircraft using data developed from the cone calorimeter. The scope of the underlying project is larger and has demonstrated the viability of the approach for external . . . . radiant fire propagation and fire development within cornpartmen&. Also, theapproach has been extended to considerations of toxicity, suppression, and structural integrity.