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.     

Smoke characteristics of coal-lined tunnel fires

Characteristics of smoke particulates generated from a coal fire in a ventilated model tunnel were investigated by laser optical transmission and by electron microscopy. Average particle diameter and mass concentration of the smoke were determined as a function of the temperature and stoichimoetry of the coal tunnel fire. Smoke particle sizes ranged from 0.2 to 0.9 μm, with larger particle sizes associated with higher smoke concentrations. These coal smoke data are relevant to several aspects of underground mine safety including the development and location of smoke detection instruments, the understanding of the fire (toxic fume) hazard, and the development of new fire protection and control techniques.     

Influence of fire retardants on the reaction‐to‐fire properties of coextruded wood–polypropylene composites

The reaction‐to‐fire properties of coextruded wood–plastic composites containing different fire retardants (melamine, zinc borate, ammonium polyphosphate, aluminium trihydroxide, natural flake graphite and expandable graphite) in the shell layer have been studied with the cone calorimetry technique. The effect of ammonium polyphosphate in combination with graphite has also been studied with a cone calorimeter test. A coextruded composite manufactured without any fire retardant addition has been used as a reference. The fire properties measured in the cone calorimeter are discussed, including the heat release rate, total heat release, smoke production, specific extinction area, CO yield and mass loss rate. The results show that the introduction of fire retardants in the shell layer of coextruded wood–polypropylene composites has a favourable effect on the fire resistance properties of the composite materials. The reaction‐to‐fire properties have been improved according to the fire classification of construction products based on the Euroclass system. Copyright © 2015 John Wiley & Sons, Ltd.     

Experimental study of the combustion characteristics of methanol‐gasoline blends pool fires in a full‐scale tunnel

The combustion characteristics of methanol‐gasoline blends pool fires were studied in a series of full‐scale tunnel experiments conducted with different methanol and gasoline blends. The parameters were measured including the mass loss rate, the pool surface temperature, the fire plume centerline temperature, the ceiling temperature, the smoke layer temperature profile, the flame height, and the smoke layer interface height. The gasoline components were analyzed by GC‐MS. The effects of azeotropism on the combustion characteristics of the different blends were discussed. On the basis of the results of the fire plume centerline temperature, the ceiling temperature, and the flame height, it shows that the tunnel fire regime gradually switches from fuel controlled to ventilation controlled with increasing gasoline fractions in the blends. The fire plume can be divided into 3 regions by the fire plume centerline temperature for the different blends. The N‐percentage rule to determine the smoke layer interface height is found to be applicable for tunnel fires with different blends for N = 26.     

Flammability hazards of typical fuels used in wind turbine nacelle

This study aims to develop a complete methodology for assessing flammability hazards of typical fuels (ie, transformer oil, hydraulic oil, gear oil, and lubricating grease) used in a wind turbine nacelle by combining different experimental techniques such as thermogravimetric analysis and cone calorimetry. Pyrolysis properties (onset temperature, temperature of maximum mass loss rate, and mass residue) and reaction‐to‐fire properties (ignition time, heat release rate, mass loss rate, and smoke release rate) were determined and used for a preliminary assessment of thermal stability and flammability hazards. Additional indices, for ignition and thermal behavior (effective heat of combustion, average smoke yield, and smoke point height, heat release capacity, fire hazard parameter, and smoke parameter, were calculated to provide a more advanced assessment of the hazards in a wind turbine. Results show that pyrolysis of transformer oil, lubricating grease, hydraulic oil, and gear oil occur in the range of 150°C to 550°C. Lubricating grease and transformer oil show the higher and lower thermal stabilities with maximum pyrolysis rate temperatures of 471°C and 282°C, respectively. The measured relation between ignition time and radiant heat flux agrees well with Janssens method (a power of 0.55). The aforementioned indices appear to provide a reasonable prediction of performance under real fire conditions according to a full‐scale fire test documented by Declercq and Van Schevensteen. The results of the study indicate that transformer oil is the easiest to ignite while lubricating grease is the most difficult to ignite but also has the highest smoke production rate; that transformer oil has the highest heat release rate while gear oil has the lowest; and that the fire hazard parameter is the highest for transformer oil and the smoke parameter is the highest for lubricating grease. The potential of this type of work to design safer wind turbines under performance‐based approaches is clearly clarified.     

Smoke characteristics of tunnel wood fires

Characteristics of smoke particulates generated from a wood fire in a ventilated model tunnel were investigated using an in situ optical and a grid sampling technique. Volume-to-surface mean diameter and mass concentration of the smoke particles, and the transmission, optical density per unit length and particulate optical density of the smokeladen exhaust gas were obtained as a function of the burning process in the tunnel. It was found that high concentration of smoke (～1 mg l^?1) were rapidly generated as the fire changed from oxygen-rich to fuel-rich burning, resulting in fast obscuration of the passageway. The simultaneous generationof large amounts of smoke and high temperature carbon monoxide (～8%) coupled with low transmission (～1% though 0.5 m) represents and extremely hazardous situation in such a fire environment. Present measurements and others from current smoke testing chambers are compared and discussed.     

Specific extinction coefficient of flame generated smoke

The experimental results for the mass specific extinction coefficient (σ_s) at λ=633 nm for flame generated smoke are summarized for seven studies involving 29 fuels. The measurements are for post‐flame smoke generated by overventilated burning. From an analysis of variance for the seven studies, it was found that between‐laboratory differences were the major source of variability. The estimated mean value of σ_s is 8.7 m²/g with an expanded uncertainty (95% confidence interval) of 1.1 m²/g. A major implication of this nearly universal value is that one can infer mass concentration of smoke by making light extinction measurements. Published in 2000 by John Wiley & Sons Ltd.     

Flammability evaluation of clean room polymeric materials for the semiconductor industry

A new methodology, identified as the 4910 Test Protocol, has been developed to evaluate the fire propagation and smoke development behaviour of polymeric materials for use in clean rooms for the semiconductor industry. This paper reviews the scientific basis of the concepts and criteria contained in the 4910 Test Protocol. For the acceptance of polymeric materials, two criteria are used: (a) Fire Propagation Index (FPI) ⩽6 (ms^−1/2)/(kWm⁻¹)^2/3 and (b) Smoke Development Index (SDI) ⩽0.4 (gg⁻¹) (ms^−1/2)/(kWm⁻¹)^2/3. Materials are tested in the ASTM E 2058 Fire Propagation Apparatus (previously identified as the Factory Mutual Research Flammability Apparatus). The Fire Propagation Index (FPI) is formulated from: (a) the Thermal Response Parameter (TRP), which relates the time‐to‐ignition to the net heat flux to the sample surface, and (b) the chemical heat release rate measured during the upward fire propagation in air having a 40% oxygen concentration to simulate flame heat transfer at large scale. The SDI is related to the smoke release rate and is obtained by multiplying the FPI value by the smoke yield. The smoke yield is defined as the ratio of the total mass of smoke released per unit mass of the vapours of the polymeric material burned. Small and large‐scale fire test data have been included in the paper in support of the 4910 Test Protocol criteria. Highly halogenated and high temperature specialty polymeric materials and highly modified ordinary thermoplastics are found to satisfy the criteria. Copyright © 2001 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.     

Poly(vinyl chloride) and its fire properties

This work provides an up‐to‐date review of the fire properties of poly(vinyl chloride) (PVC) materials, both rigid (unplasticized) and flexible (plasticized). The fire properties addressed include ignitability, ease of extinction (oxygen index), flame spread (small scale and intermediate scale), heat release, smoke obscuration, smoke toxicity, hydrogen chloride emission and decay, and performance in real‐scale fires. This comprehensive review includes a wide selection of references and tables illustrating the properties of PVC materials in comparison with those of other polymeric materials, including, in many instances, wood materials. The work puts these fire properties in perspective, showing that the heat release rate (the key fire property) of rigid PVC (and that of properly flame‐retarded flexible PVC) are among the lower values found for combustible materials. This work also shows that the smoke toxicity and smoke obscuration resulting from burning PVC materials in real‐scale fires is in the same range as those of other materials.     

Characterization of the fire environments in central offices of the telecommunications industry

Eight free burning and two sprinklered fire tests were performed with electrical cable trays and live digital switch racks in a large enclosure to simulate telecommunications central office (TCO) fires started by electrical overheating. Very‐slow‐growing (non‐flaming), slower‐growing (partially flaming) and low‐intensity‐faster‐growing (flaming) fires releasing gray‐white, gray, and black smoke, respectively, were observed in the tests. Under quiescent conditions present in the unvented enclosure fire tests for cables, very‐slow‐growing fires were detected in about 1452 s, whereas the slower‐growing fires were detected in about 222 s by commercial fire detectors. Under ventilation conditions typical of TCOs, detection times were very similar for the five types of commercial TCOs fire detectors used in the tests. The average detection times for slower‐growing fires (cable fires) and low‐intensity‐faster‐growing fires (digital switch rack fires) were 242±17% and 249±11%s respectively. The TCO procedures to reduce smoke damage from fires (on fire detection, inlet ventilation flow is turned off and exhaust flow is turned on) were found to be beneficial. The extent of smoke damage decreased significantly with an increase in the exhaust flow rate. The chloride ion mass deposition suggested that equipment recovery would be possible in the smoke environment if the cable vapor concentration could be reduced below about 3 g/m³. The metal corrosion rate was found proportional to the 0.6th power of the smoke concentration, similar to that found for the corrosion of metal surfaces exposed to aqueous solutions of HCl and HNO₃ and for acid rain with no protective layer at the surface. Sprinkler water was found to wash down the smoke deposits on the surfaces with little indication of corrosion enhancement. Copyright © 2003 John Wiley & Sons, Ltd.     

Expandable graphite's versatility and synergy with carbon black and ammonium polyphosphate in improving antistatic and fire‐retardant properties of wood flour/polypropylene composites

This study investigated the antistatic and fire‐retardant properties of wood flour/polypropylene composites consisting of carbon black (CB), ammonium polyphosphate (APP), and expandable graphite (EG) through resistance meter measurement, cone calorimetry (CONE), thermogravimetric analysis (TGA), and scanning electron microscopy. Antistatic property testing confirmed a positive effect between CB and EG on discharging electrostatic charge. Electrostatic charge was thus considered able to be conducted between CB particles through EG, which acted as a bridge in the CB/EG ‐ treated composites. The results of CONE tests showed that EG significantly reduced the smoke release of the wood plastic composites (WPCs), including total smoke release (TSR), average specific extinction area (SEA), and production of carbon monoxide. During the WPCs burning process, a compound of EG and APP showed synergistic effects which decreased heat release and fixed the residual char. TGA results demonstrated that combining EG with APP, as opposed to using EG only, effectively increased the residual mass and decreases the initial thermal decomposition temperature of the WPCs. Addition of APP caused the wood flour char by catalyzing at a lower temperature, moreover, EG and APP displayed good synergistic effects on fire inhibition and smoke suppression. POLYM. COMPOS., 38:767–773, 2017. © 2015 Society of Plastics Engineers     

Removal characteristics and distribution of indoor tobacco smoke particles using a room air cleaner

The objective of this study is to analyze the removal characteristics and distribution of indoor air pollutants by a room air cleaner. A pollutant removal effect according to room volume and measurement point was evaluated in an indoor room. A series of filtration efficiency tests were performed on only the electrostatic precipitator of the room air cleaner. The measurements of filter efficiency and pressure drop across the electrostatic precipitator were made using an ASHRAE 52.1-1992 filter test system and an opacity meter to measure the particle concentration upstream and downstream of the test filter. Also the performance of the air cleaner in the room was evaluated by examining tobacco smoke particle concentration. The size distribution of the tobacco smoke particles was 1.27 μm in mass median diameter and a geometric standard deviation of 1.313 μm. The efficiency of the electrostatic filter was measured as 78.6% with dust particles of 1.96 μm in mass median diameter and 1.5m/s face velocity. The tobacco smoke particle concentration as a function of time decayed exponentially. The contaminant removal effect was increased when increasing the effective clean air exchange rate (ηQ/V), which is 0.0780 min^?1 for 51 m³ room and 0.0235 min^?1 for 149 m³ room. This study clearly shows that a room air cleaner with an electrostatic precipitator is effective in removing tobacco smoke particles. The removal characteristics and distribution of indoor air pollutants in other rooms is predicted based on empirical modeling.     

Experimental study of fire compartment with door opening and roof opening

A series of reduced‐scale experimental fires was conducted to study the characteristics of fire induced vent flows in a reduced‐scale post‐flashover fire compartment with a door opening and a roof opening. The fire source was a heptane pool fire near the wall furthest from the door vent. In the study, the roof vent opening area was systematically varied between experiments and the characteristics of vent flows through the door opening are presented as a function of the roof vent opening area. The experimental results show that the mass flow rate of air into the compartment increases linearly as the size of roof vent opening increases. Analytical vent flow calculations based on the hydrostatic pressure difference between two quiescent environments are presented for a post‐flashover fire compartment with both horizontal and vertical openings. The calculated results are in good agreement with the experimental measurements. Copyright © 2005 John Wiley & Sons, Ltd.     

Influence of multisource fire on temperature distribution and natural smoke exhaust effect in urban tunnels with a shaft

The combustion characteristics of multisource fire and single-source fire are quite different, and there is little research on the influence of multisource fire on the natural smoke extraction effect of shaft in urban tunnels. Therefore, in this article, the method of numerical simulation was used to study the influence of fire power and distance between two fire sources on the natural smoke extraction effect of shaft and the temperature distribution in tunnel in the case of multisource fire. Typical characteristics of smoke are analyzed, such as mass flow rate, temperature distribution, velocity vector, and CO concentration. The simulation results show that when there is a certain distance between the fire sources, the two flames are inclined and close to each other. The smoke temperature under the ceiling is higher under multiple fire sources than that under single fire source. In addition, when one of the fire sources is located at the downstream of the shaft, the smoke emission in the shaft is relatively high. As the distance between fire sources continues to increase, the smoke exhaust rate basically remains stable, and an empirical relationship between smoke exhaust rate and fire source location is established.     

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.     

Smoke gas analysis by Fourier transform infrared spectroscopy – summary of the SAFIR project results

The determination of toxic components from fire gases is difficult because the environment is hot, reactions are often temperature dependent, and a lot of soot may be produced. Due to the different properties of the gas components, a different time‐consuming procedure for each species has traditionally been used. The use of FTIR (Fourier transform infrared) spectrometers as a continuous monitoring technique overcomes many of the problems in smoke gas analyses. FTIR offers an opportunity to set up a calibration and prediction method for each gas showing a characteristic spectral band in the infrared region of the spectrum. The objective of the SAFIR project was to further develop the FTIR gas analysis of smoke gases to be an applicable and reliable method for the determination of toxic components in combustion gases related to fire test conditions. The optimum probe design, filter parameters and the most suitable sampling lines in terms of flow rate, diameter, construction material and operating temperature have been specified. In the large scale, special concern was given to the probe design and the effects of the probe location as well as practical considerations of the sampling line length. Quantitative calibration and prediction methods have been constructed for different components present in smoke gases. Recommendations on how to deal with interferents, non‐linearities and outliers have been provided and a verification method for the spectrometer for unexpected variations and for the different models have been described. FTIR measurement procedures in different fire test scenarios have been studied using the recommendations of this project for measurement techniques and analysis and an interlaboratory trial of the FTIR technique in smoke gas analysis was carried out to define the repeatability and reproducibility of the method in connection with a small scale fire test method, the cone calorimeter. Copyright © 2000 John Wiley & Sons Ltd.     

CFD modeling approach of smoke toxicity and opacity for flaming and non‐flaming combustion processes

Current engineer's methods of fire safety design include various approaches to calculate the fire propagation and smoke spread in buildings by means of computational fluid dynamics (CFD). Because of the increased computational capacity, CFD is commonly used for prediction of time‐dependent safety parameters such as critical temperature, smoke layer height, rescue times, distributions of chemical products, and smoke toxicity and visibility. The analysis of smoke components with CFD is particularly complex, because the composition of the fire gases and also the smoke quantities depends on material properties and also on ambient and burning conditions. Oxygen concentrations and the temperature distribution in the compartment affect smoke production and smoke gas toxicity qualitatively and quantitatively. For safety designs, it can be necessary to take these influences into account. Current smoke models in CFD often use a constant smoke yield that does not vary with different fire conditions. If smoke gas toxicity is considered, a simple approach with the focus on carbon monoxide is often used. On the basis of a large set of experimental data, a numerical smoke model has been developed. The developed numerical smoke model includes optical properties, production, and toxic potential of smoke under different conditions. For the setup of the numerical model, experimental data were used for calculation of chemical components and evaluation of smoke toxicity under different combustion conditions. Therefore, averaged reaction equations were developed from experimental measurements and implemented in ANSYS CFX 14.0. Copyright © 2015 John Wiley & Sons, Ltd.     

Comparison of flammability measurements in vertical and horizontal exhaust duct in the ASTM E‐2058 fire propagation apparatus

The ASTM E‐2058 fire propagation apparatus (FPA) is capable of measuring time to ignition, chemical and convective heat release rates, mass loss rate, smoke generation rate, generation rates of CO, CO₂ and O₂ consumption rate, effective (chemical) heat of combustion and vertical fire propagation of materials. The original design of the FPA incorporated a vertical exhaust system with the measurement section finishing about 3.5 m from the floor. The exhaust measuring duct of the new FPA is horizontally oriented to enable its use in a wider range of laboratory environments. In this paper, the functionality of the new FPA was compared with the original FPA. The measurements and results indicate that the performance of the new FPA is equivalent to the original FPA. Copyright © 2003 John Wiley & Sons, Ltd.     

A numerical study on the effects of naturally ventilated shaft and fire locations in urban tunnels

In more and more tunnels, natural ventilation mode with vertical shafts has been gradually employed. However, there are few studies investigating the influences of fire and shaft positions on natural ventilation performance currently. Therefore, this study investigated the effects of the transverse distance from fire source to tunnel sidewall, the longitudinal distance from fire source to shaft, and the transverse distance from shaft to sidewall on natural ventilation effectiveness in a tunnel fire by using Fire Dynamics Simulator. The typical characteristic parameters of smoke, such as mass flow rate, temperature distribution, and velocity vector were analyzed; besides, the phenomenon of plug‐holing was discussed. The results have shown that the mass flow rate of gas exhausted by the shaft decreases slightly with the increase of longitudinal distance from fire source to shaft. When the longitudinal distance from fire source to shaft is constant, changing the transverse distance from shaft to sidewall will have a more obvious effect on the effectiveness of exhausting smoke than changing the transverse distance from fire source to sidewall; in addition, the phenomenon of plug‐holing is more serious when the shaft is close to the sidewall.