Burning behaviors of selected chlorosilanes and SiH‐containing siloxanes

Chlorosilanes are silanes containing the Si‐Cl functional group and SiH‐containing siloxanes are siloxanes containing the Si‐H functional group. Some chlorosilanes and SiH‐containing siloxanes present potentially high fire or explosion hazards during handling, storage, transport and process operations. Cone calorimeter tests have been used to study the burning behaviors of selected chlorosilanes and SiH‐containing siloxanes at various incident heat fluxes to simulate pool fire burning. The peak heat release rate of a silicon intermediate obtained from the cone calorimeter at 15 kW/m² incident heat flux was very close to that measured by a relatively large‐scale field test. The flammability of monochlorosilanes was similar to that of organic hydrocarbons having comparable volatility. The flammability of chlorosilanes descends in the order of monochlorosilanes, dichlorosilanes and trichlorosilanes. SiH‐containing siloxanes ignited faster than non‐SiH‐containing siloxanes because of the reactive silicon‐hydrogen linkages. The ignition of SiH‐containing siloxanes was much more violent than the ignition of non‐SiH‐containing siloxanes. The SiH‐containing siloxanes exhibited a lower peak heat release rate, less total heat released and a lower peak smoke extinction coefficient compared with non‐SiH‐containing siloxanes having comparable volatility. Copyright © 2004 John Wiley & Sons, Ltd.     

Investigation of a combustible material in the fire of Hengyang merchant's building

Agaric, a kind of important combustible material in the fire of Hengyang merchant's building, was investigated using different experiment equipments. Its degradation and pyrolysis behavior were studied by means of thermogravimetric and kinetic analysis and pyrolysis gas chromatography–mass spectroscopy analysis. External radiation heat and internal heat were used to ignite the agaric. For external radiation ignition, a series of bench‐scale fire tests were done in cone calorimeter in accordance with ISO 5660. As for the internal heat ignition, a fire test was carried out in a full‐scale room in accordance with ISO 9705. Multi‐parameter measurement, including heat release rate (HRR), mass loss rate (MLR), temperature field and species concentration, has been accomplished. Meanwhile, the process of a full‐scale fire test was numerically simulated. The computational results were consistent with experiment data, which will lay down a good foundation for further study in fire reconstruction of the whole fire. Copyright © 2008 John Wiley & Sons, Ltd.     

Comparison of simulated wet bench fires with small‐ and intermediate‐scale fire tests

Fire hazard studies of clean room facilities indicated that significant losses due to fire may occur in the semiconductor industry. The present study reports the results of full‐scale wet bench fire tests conducted (1) to assess the fire hazards of existing wet bench materials not meeting the listing requirement of NFPA 318, (2) to assess the impact on wet bench fires of engineered materials with improved flammability characteristics, and (3) to compare the observed fire behavior with the results of simpler small‐ and intermediate‐scale fire tests using the same materials. The full‐scale wet bench fires were observed to be consistent in terms of chemical heat release rate, fire propagation, and smoke generation with the results of the small‐ and intermediate‐scale test results. The simpler fire tests are incorporated in FM Approvals 4910 certification for materials to be used in semiconductor fabrication facilities. The small‐scale test protocol is also standardized in NFPA 287. Copyright © 2008 John Wiley & Sons, Ltd.     

Fire and flame retardants for PVC

The flammability performance of PVC plays a significant role in its selection for many applications. Its relatively high chlorine content (56.8%) makes it more resistant to ignition and burning than most organic polymers. In the case of flexible PVC, the plasticizers that contribute flexibility in most instances detract from its resistance to fire. To meet specifications such as oxygen index, heat release, smoke evolution, or extent of burning in cable tests, flame‐retardant (FR) and smoke‐suppressant (SS) additives are often incorporated. Synergistic combinations of FR and SS additives help PVC formulations meet many stringent FR specifications cost effectively.     

Bench Scale Tests on Controlling Plastic Fires with Water Mists

Bench scale tests are proposed to study the performance of a water mist fire suppression system on plastic fires. The effects of water mist on burning solid polymethylmethacrylate (PMMA) and polyvinylchloride (PVC) are compared with a cone calorimeter. A scaled nozzle developed earlier for discharging water mist in a cone calorimeter was used. Operating pressures of 0.2–0.7 MPa, corresponding to water flow rates of 68 mL/min and 134 mL/min, were used. It was observed that PMMA samples could be ignited easily and liberated significant amounts of heat at high release rates. PVC was more difficult to ignite, but gave out large quantities of smoke. Discharging water to both did not increase the heat release rate significantly. However, both smoke quantity and carbon monoxide concentration increased. This was more obvious for PMMA fires. Hazard assessment parameters for thermal aspects and smoke were measured and presented as a ‘hazard diagram' to understand the action of water mist and the potential for re‐ignition. It is suggested that bench scale tests can also give useful results for designing water mist systems. The discharging time of water mist is a key factor in controlling PMMA fires. If the discharging time is not long enough, re‐ignition might occur once the discharging of water stops.     

Experimental study on ignition and combustion characteristics of typical oils

The impact of radiant heat flux on ignition and combustion behavior of typical oils (diesel, lubricating oil, and aviation kerosene) was conducted in a cone calorimeter. A circular steel pan with a diameter of 10 cm was used to contain diesel, lubricating oil, and aviation kerosene without water sublayer. Using the standard oxygen consumption method, we obtained ignition time, heat release rate, mass loss rate, extinction coefficient, CO, and CO₂ yield, and average specific extinction area was calculated from the extinction coefficient. Janssens' method was adopted in this study to deal with ignition time and radiant heat flux under a 0.55 power rule. Results show that the fitting through Janssens' method is good for ignition time of diesel, lubricating oil, and aviation kerosene and radiant heat flux. Moreover, heat release rate, mass loss rate, and CO/CO₂ ratio appear to positively correlate with radiant heat flux, whereas average specific extinction area varies in a certain range. Copyright © 2013 John Wiley & Sons, Ltd.     

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.     

Experimental investigation and numerical modelling of the fire performance for epoxy resin carbon fibre composites of variable thicknesses

This paper applies a unique integrated approach to determine the flammability properties of a composite material (epoxy with carbon fibre) and compares its fire behaviour at two different thicknesses (2.1 and 4.2 mm) by performing small scale (thermo‐gravimetric analysis (TGA)/Fourier transform infrared radiation) and meso‐scale tests (cone calorimeter). For small‐scale tests, experiments were conducted in nitrogen using TGA coupled to gas analysis by Fourier transform infrared radiation. These results allow the determination of thermal stability, main degradation temperature and main gaseous emissions released during the thermal degradation. For meso‐scale tests, experiments were carried out using a cone calorimeter with sample dimensions of 100 × 100 mm at five heat fluxes (30, 40, 50, 60 and 70 kW/m²). The results show that the ignition time increases with an increase in the thickness of the material. Relative hazard classification of the fire performance of the current composites has also been compared with other materials using parameters obtained elsewhere. In addition, the effective ignition, thermal and pyrolysis properties obtained from the ignition and mass loss rate experiments for the 4.2‐mm thick samples were used in a numerical model for pyrolysis to predict well ignition times, back‐surface temperatures and mass pyrolysis rates for all heat fluxes as well as for the 2.1‐mm thick samples. Note that the ignition temperature obtained in the cone agrees with the main degradation temperature in the TGA. The flammability properties deduced here can be used to predict the heat release rate for real fire situations using CFD modelling. 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.     

The use of fire‐retardant intumescent mats for fire and heat protection of glass fibre‐reinforced polyester composites: Thermal barrier properties

This study investigates the use of integral, hybrid intumescent thermal barriers (mats) to provide surface protection to the core fibre‐reinforced polyester composite structural integrity when exposed to a fire or heat source. Glass fibre‐reinforced composites protected by intumescent mats/fabrics containing silicate fibres, expandable graphite and in some cases borosilicate glass bounded together by an organic matrix have been evaluated for fire performance under a constant heat flux of 50kW/m². The effect of insulative fabric thickness as well as chemical composition on the flammability of the resultant hybrid composites is evaluated. Glass fibre‐reinforced polyester (GRP) composites without any surface protection have a relatively higher time‐to‐ignition and peak heat release rate values when compared with core composites protected by insulative fabrics. Thermograms representing the variation of temperature on the reverse side of the hybrid composites with time when exposed to a constant heat flux show that the inclusion of intumescent surface barriers results in retarded temperature increments within the core GRP composites. Copyright © 2009 John Wiley & Sons, Ltd.     

Molar group contributions to polymer flammability

The specific heat‐release rate is the molecular‐level fire response of a burning polymer. The Federal Aviation Administration obtains the specific heat‐release rate of milligram samples by analyzing the oxygen consumed by the complete combustion of the pyrolysis gases during a linear heating program. Dividing the specific heat‐release rate (W/g) by the rate of the temperature rise (K/s) of a sample during a test gives a material fire parameter with the units (J/g K) and significance of the heat (release) capacity. The heat‐release capacity appears to be a true material property that is rooted in the chemical structure of the polymer and is calculable from additive molar group contributions. Hundreds of polymers of known chemical compositions have been tested to date, providing over 40 different empirical molar group contributions to the heat‐release capacity. Measured and calculated heat‐release capacities for over 80 polymers agree to within ±15%, suggesting a new capability for predicting flammability from the polymer chemical structure. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 548–563, 2003     

Cone calorimeter testing of foam core sandwich panels treated with intumescent paper underneath the veneer (FRV)

Surfaces of novel foam core sandwich panels were adhered with intumescent fire‐retardant paper underneath the veneers (FRV) to improve their flammability properties. The panels were evaluated by means of cone calorimeter test (ASTM E 1354). Variables tested were different surface layer treatments, adhesives used for veneering, surface layer thicknesses, and processing conditions, having the objective of obtaining similar or better flammability as that of solid particle boards. Previous research showed that sandwich panels without FRV compared to panels with FRV generally had much higher heat release rates, somewhat higher heat of combustion and much higher smoke production due to the polymeric foam component of tested panels. The present study shows that using FRV adhered to the surface layer of sandwich panels dramatically improved flammability properties; the best FRV performance resulted from panels produced with thicker face layer (5 mm) and lower press temperature (130°C) and adhered with an acrylic thixotropic adhesive. Such protected foam core particleboard has heat release rate profiles as low as that is typical of commercially available fire‐retardant–treated plywood, thus implying a low flammability rating when tested in accordance with both single burn item (Euro Class B anticipated) and steiner tunnel (North America Class A anticipated) tests.     

Development of fire‐retarded materials—Interpretation of cone calorimeter data

There is little consensus within the fire science community on interpretation of cone calorimeter data, but there is a significant need to screen new flammability modified materials using the cone calorimeter. This article is the result of several discussions aiming to provide guidance in the use and interpretation of cone calorimetry for those directly involved with such measurements. This guidance is essentially empirical, and is not intended to replace the comprehensive scientific studies that already exist. The guidance discusses the fire scenario with respect to applied heat flux, length scale, temperature, ventilation, anaerobic pyrolysis and set‐up represented by the cone calorimeter. The fire properties measured in the cone calorimeter are discussed, including heat release rate and its peak, the mass loss and char yield, effective heat of combustion and combustion efficiency, time to ignition and CO and smoke production together with deduced quantities such as FIGRA and MARHE. Special comments are made on the use of the cone calorimeter relating to sample thickness, textiles, foams and intumescent materials, and the distance of the cone heater from the sample surface. Finally, the relationship between cone calorimetry data and other tests is discussed. Copyright © 2007 John Wiley & Sons, Ltd.     

Combustion characteristics of crude oils

Small‐scale free‐burning pool fire tests were conducted in a cone calorimeter to obtain the combustion characteristics of 14 different crude oils. Measurements included the heat release rate based on oxygen consumption calorimetry, mass loss rate, radiative heat flux from the flame to a nearby target, liquid fuel temperature, extinction coefficient and CO₂ and CO concentrations in the exhaust duct. The effective heat of combustion, radiative heat loss fraction and smoke yield were calculated on the basis of the measured data. It was found that the heat release rate, mass loss rate, flame radiation and smoke yield were a function of the type of crude oil. The effective heat of combustion, extinction coefficient and radiative heat loss fraction were nearly constant for the range of crude oils evaluated in this programme. The heat release rate, mass loss rate, flame radiation and smoke yield appeared to correlate well with the crude oil density. Copyright © 2001 John Wiley & Sons, Ltd.     

Fire properties of surrogate refuse‐derived fuels

This paper investigates the fundamental fire properties of surrogate refuse‐derived fuels (RDF), a class of multicomponent materials characterized by high void fraction, with particles of polydisperse sizes and significant internal porosity. A surrogate RDF was developed to improve the reproducibility of experimental measurements. This surrogate RDF reflects typical municipal solid waste collected in the city of Newcastle, in the state of New South Wales in Australia. The material consists of shredded newspaper, wood, grass and plastic bags, with small amounts of sugar and bread. About 95% of the material passes through 50 mm square screens, as required by ASTM E828 standard for RDF‐3 specification. The experiments presented in this paper were performed with the components of the RDF dried in a forced‐air oven at 103° C, except for grass which was dried under nitrogen. The material was found to be very hygroscopic, requiring special care in handling. The experiments performed in the cone calorimeter were designed to measure the heat release rate, total heat release, time to ignition, time to extinction, effective heat of combustion and formation of CO during the combustion process, as a function of sample thickness, sample density and the magnitude of the imposed radiative heat flux. The thermophysical properties of the surrogate material were either measured (solid density, void space, particle density, particle porosity) or extracted from the published data (heat capacity). The present surrogate RDF material was found to ignite easily, within a few seconds of the imposition of the incident heat flux of 40 kW m^?2, and then to reach rapidly the peak heat release rate of 110–165 kW m^?2. The deduced values of the critical heat flux, pyrolysis temperature and effective thermal conductivity are 9–10 (±2) kW m^?2, 280–310 (±30)° C, and 0.4–0.7 (±0.3) W m^?1 K^?1, respectively, depending on the material density. The effective heat of combustion of the RDF was estimated as 15.3 MJ kg^?1. The material produced 1 kg of CO per 18 kg of dried RDF, mostly during smouldering phase after the extinguishment of the flaming combustion. These results indicate that dried RDF pose significant fire risks, requiring that fire safety systems be implemented in facilities handling RDF. Copyright © 2005 John Wiley & Sons, Ltd.     

Experimental study of smoke effects on energized electrical cabinets located nearby a lubricant oil pool fire

This paper presents an experimental study of smoke exposure effects on potential malfunction of three electrical cabinets located nearby an oil pool fire. This study was performed as part of the PRISME‐2 international OECD project. Lubricant oil was used as fire source, and three real energized electrical cabinets were used as targets exposed to smoke in the adjacent room to the fire room. The main fire properties, as well as the fire consequences, such as gas temperatures and smoke concentrations in the rooms, and the cabinets are presented in detail. The heat release rate was thus assessed at around 500 kW for nearly all the fire duration, and maximum gas temperatures reached 300°C in the fire room, and 120°C in the adjacent room. Moreover, the maximum gas temperatures and soot mass concentrations inside the cabinets ranged from 90 to 120°C and from 0.3 to 1 g/m³, respectively. Nevertheless, continuous electrical monitoring of the three cabinets did not highlight malfunction. After the experiment, monitoring test of the cabinets was conducted to investigate the potential effects. The isolation resistance of electrical circuits on the most severe smoke exposed cabinet reduced during the monitoring test. It seemed the soot deposition have caused it.     

Fire performance studies on glass-reinforced plastic laminates

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.     

A study on fire behaviour of combustible components of two commonly used photovoltaic panels

Photovoltaic (PV) modules are installed in some modern buildings for generating renewable energy. When a building catches fire, burning PV panels can contribute to an already very hazardous environment. Two common polycrystalline silicon PV samples A and B were selected with their chemical composition analysed by the Fourier transform infrared spectroscopy with justification by X‐ray photoelectron spectroscopy results. Sample A was confirmed to be a silicate product with polyurethane adhesive, and sample B has epoxy resin and is likely to have flame retardant as claimed. Thermal analysis by heating the samples was carried out using thermogravimetric analysis and thermogravimetric analysis coupled with infrared spectroscopy. The fire behaviour was then studied by a cone calorimeter under radiative heat fluxes from 10 to 70 kWm^?2. Three key parameters representing flashover propensity, total heat release per unit area and smoke toxicity hazard were obtained from the cone calorimeter tests for ranking the thermal and smoke hazards. The thermal hazards of both PV samples are low, at least during the early stage of a fire without flame acting directly on the sample. However, vast quantities of smoke were emitted from burning PV panels under high heat fluxes. Copyright © 2016 John Wiley & Sons, Ltd.     

Mechanical,thermal, tribological,and flammability properties of polybutylene terephthalate composites: Comparing the effects of synthetic wollastonite nanofibers,natural wollastonite,and graphene oxide

Polybutylene terephthalate (PBT) composites were prepared with 1.0 phr synthetic wollastonite nanofibers (SWN), natural wollastonite (NW) and graphene oxide (GO) to study the effect of different fillers on mechanical, thermal, tribological, and flammability properties. The properties of PBT composites are related to the size, structure, and interfacial adhesion of the fillers in PBT matrix. PBT/SWN demonstrated the highest tensile strength and Young's modulus (6% and 9% increment), followed by PBT/NW (1.3% and 7% increment) and PBT/GO (2% decrement and 4% increment). PBT/SWN gave the highest degradation temperature (409°C), followed by PBT/GO (404.7°C). The maximum enhancement in wear resistance (73%) by PBT/SWN and anti-friction performance (26%) by PBT/GO evinced the excellent load-bearing ability of SWN and the great lubricating effect of GO. PBT/NW had the lowest peak heat release rate, smoke, and carbon dioxide production rate. This study shows that PBT composites have great potential in different automotive applications.     

Flame retardant performance of various UL94 classified materials exposed to external ignition sources

The flammability of eight halogen‐free styrene resins and one halogen‐containing styrene resin was characterized by UL 94 VB, LOI and cone calorimeter tests. Their burning behaviour was also measured when exposed to three external ignition sources (methenamine tablet, candle, paper ball). Five resins were used for 19″ monitor housings and the others for 25″ TV. The LOI values of UL 94 V‐2, V‐1 and V‐0 rated resins were higher than that of HB. The heat release rate decreased as the UL 94 ratings increased from HB to V‐0. When these resins were exposed to three external ignition sources, UL 94 V‐1 and V‐0 rated resins showed a self‐extinguishing property after removal of the fire and did not cause fire growth in either 19″ monitor or the 25″ TV housings in all cases. However, UL 94 V‐2 and HB rated resins were easily ignited and spread fire by dripping burning trickles. The burning rate of V‐2 resin was slower than that of HB. Copyright © 2004 John Wiley & Sons, Ltd.