Spontaneous Ignition Temperatures Research Articles

Adsorbent Properties of Porous Boron Nitride and Activated Carbon: A Comparative Study.

Porous boron nitrides possess beneficial properties such as high thermal and chemical stability which are critical for applications in adsorption processes. In order to assess possible fields of applications, trace-level adsorption isotherms of different hydrocarbons on two synthesized porous boron nitrides and two commercial activated carbons are compared. By normalizing the adsorptive loadings on the micropore surface area, superior adsorption performances of the BN materials on polar and aromatic adsorptives with up to 50% higher loadings compared to the activated carbons can be shown. Nonpolar adsorptives, on the other hand, feature higher specific loadings on the activated carbon. Consequently, the size of the micropore surface appears to be decisive for nonpolar adsorptives, while the higher polarity of the boron nitrides is the dominant influencing factor for the adsorption of polar and aromatic components. For an energetic study of the adsorbents, calorimetric experiments were performed to identify and discuss adsorbent-adsorptive interactions. While the initial heat of adsorption of the nonpolar n-hexane is lower on the boron nitride than on the activated carbon due to a less favorable spatial arrangement, toluene shows comparable values on both adsorbent classes and the polar acetone shows higher values on the polar boron nitride. Considering technical applications in adsorption technology, the thermal stability of the boron nitrides is investigated using spontaneous ignition temperatures and points of initial oxidation. Here, the porous boron nitrides with oxidation temperatures above 900 °C show about 400 °C higher values and thus a significantly higher thermal stability.

Fire Resistance Evaluation of New Wooden Composites Containing Waste Rubber from Automobiles.

Particleboards containing waste rubber (tires and mixtures of isolators and carpets) filler were evaluated from the point of view of its flammability. The assessment of the utilization of these composites in the construction industry was analyzed through the determination of their spontaneous ignition temperatures, mass burning rate and calorific value. Based on the results of spontaneous ignition temperatures, similar values between particleboards and particleboards containing 10%, 15% and 20% of waste tires were obtained. The average time was from 298 s to 309 s and the average temperature was from 428.1 °C to 431.7 °C. For the mass burning rate, there were similar results between particleboards and particleboards containing 10% of waste tires and waste rubber. The time to initiation was 34 s and the time to reaching a maximal burning rate was from 66 s to 68 s. The calorimetry results showed similar properties for the calorimetric value and ash content in particleboards and particleboards containing 10% of waste tires and waste rubber. The calorific value was from 18.4 MJ·kg−1 to 19.7 MJ·kg−1 and the ash content from 0.5% to 2.9%.

공업용 시너인 Ethylbenzene과 Xylenes계의 인화점, 최소자연발화온도 및 폭발한계에 관한 연구

Every year, fires caused by thinners are steadily occurring, and even life-threatening disasters are occurring. However, even though the component ratio is expressed as a range in MSDS(Material Safety Data Sheet) provided to workers, information on flash point and auto-ignition temperature is expressed as a single point or is not provided in most cases. Therefore, it was determined that it was necessary to consider the flash point and autoignition temperature according to the component ratio. In this study, the flash point and auto-ignition temperature of pure substances and ethylbenzene and xylenes system of industrial thinners were measured, and the explosion limits were predicted by antoine’s equation and le chatelier’s law through the measured flash point. The prediction formula for spontaneous ignition temperatures in different compositions is shown. The presented experimental data are expected to be provided as reference data to ensure safety in the process of using or manufacturing thinner.

The development of a model for the prediction of polymer spontaneous ignition temperatures in high pressure enriched oxygen across a range of pressures and concentrations

High pressure enriched oxygen is used in a wide number of areas, including aircraft, medical breathing apparatus, diving, mining and mountaineering operations. It is also used for a number of industrial processes, but is most commonly used for combustion. Where the pressure or concentration of oxygen is increased well above that of atmospheric, oxidation reactions occur more readily, and at a faster rate, relative to those under atmospheric conditions. Thus the criteria used for polymer selection is key to preventing, or at least limiting, the possibility of a catastrophic oxygen incident which endangers both property and human life. In this work spontaneous ignition temperature (SIT) data obtained in high pressure enriched oxygen from both differential scanning calorimetry and oxygen bomb testing are compared. A model is derived to enable the calculation of a SIT of a non-metal at any pressure and oxygen concentration using existing test data from other pressures. This has been shown to work with reasonable success for most materials tested, being validated using the comparison of test data from the oxygen bomb test and Pressurised Differential Scanning Calorimetry (PDSC) testing. These results may indicate the suitability of a PDSC for safety testing in the future. Further work is needed to increase the data base of ignition test data from PDSCs, and thermodynamic constants to allow for the direct comparison, and to assess the suitability of this apparatus for safety testing of more materials.

Effect of Upgraded Lignite Product Water Content on the Propensity for Spontaneous Ignition

The spontaneous ignition that occurs with upgraded lignite products is a concern for its storage, handling, and transportation. The Basket testing method and Oxidation Kinetics testing method were used to identify the propensity for upgraded lignite products to spontaneously ignite. The evaluation index for the Basket testing method was spontaneous ignition temperatures and duration. The fundamental evaluation index (I) for the Oxidation Kinetics testing method was used to evaluate the propensity for spontaneous ignition. For both testing methods, all three of the lignite samples (Huolinhe lignite, Hailaer lignite, and Indonesia lignite) showed that the propensity for spontaneous ignition decreased linearly with the increase in water content of the upgraded lignite product. Commonly used Chinese bituminous coals, which are not prone to spontaneous ignition, were used as a benchmark for determining the recommended water content for upgraded lignite products. For Huolinhe lignite, Hailaer lignite, and Indonesia lignite, the recommended water contents of the upgraded products are 6.53%, 4.28%, and 7.83%, respectively. The method that was developed to determine the recommended water content could be used to guide engineering design and operations when using upgraded lignite that is highly susceptible to spontaneous ignition.

N-Pentanol과 Ethylbenzene 혼합물의 최소자연발화온도의 예측

The MSITs(Minimum Spontaneous Ignition Temperatures) or AITs(Autoignition Temperatures) describe the minimum temperature to which a substance must be heated, without the application of a flame or spark, which will cause that substance to ignite. This study measured the MSITs(Minimum Spontaneous Ignition Temperatures) of n-pentanol+ethylbenzene system by using ASTM E659 apparatus. The MSITs of pure n-pentanol and ethylbenzene were and , respectively. The experimental MSITs of n-pentanol+ethylbenzene system were a in good agreement with the MSIT calculated by the proposed equations with a few A.A.D.(average absolute deviation).

Spontaneous ignition of ultra-fine magnesium powder without an original oxide coat at room temperature in O 2/N 2 mixture streams

To examine the pyrophoric characteristics of Mg powder, we generated ultra-fine Mg particles (average particle diameter: about 0.3 μm) without an original oxide coat in an Ar stream. The ignition of the powder was measured by using the impinging O 2/N 2 mixture streams over a wide range of the experimental parameters: pressure, oxygen concentration and velocity of the streams. The Mg powder was found to ignite even at room temperature. The spontaneous ignition temperatures in the range of 278 ∼ 324 K were insensitive to all the experimental parameters. The ignition delay time had a tendency to decrease with increasing experimental parameters. The ignition process of the Mg powder was found to be controlled by the surface reaction rate without an oxide coat. We proposed a new ignition hypothesis considering a critical oxide thickness on the Mg powder particles at the transition temperature from protective to non-protective nature: that is, the ignition of the Mg powder occurs when the powder temperature rises above the transition temperature before surface reactions form a protective oxide coat with the critical thickness on the individual particle surfaces. According to this hypothesis, an ignition model of Mg powder cluster was developed, and the relation between the spontaneous critical ignition temperature and the ultra-fine powder size, depending on the critical thickness of the protective oxide coat, was clarified. The critical oxide thickness was estimated.

99/00157 Determination of spontaneous ignition temperatures of ester-based aviation lubricants using pressure differential scanning calorimetry

99/00157 Determination of spontaneous ignition temperatures of ester-based aviation lubricants using pressure differential scanning calorimetry

Determination of spontaneous ignition temperatures of ester‐based aviation lubricants using pressure differential scanning calorimetry (PDSC)

AbstractThe usefulness of pressure differential scanning calorimetry (PDSC) in the determination of spontaneous ignition temperatures (SITs) of newly developed ester‐based aviation turbine engine oils is shown. Data on the reproducibility of measurements on aluminium and steel surfaces is given.

Ignition and combustion of aluminum in oxygen/nitrogen mixture streams

The ignition and combustion of a solid cylinder of Al was studied experimentally by using the stagnation region of impinging O 2 N 2 ( 20 80 ) mixture streams over a wide range of pressure and velocity of the streams. When an original oxide coating did not exist on the Al surface, the critical spontaneous ignition temperatures were lower than the melting point of Al 2O 3, decreasing with reduction in pressure and velocity of the streams. Whether surface reactions initially formed a protective Al 2O 3 film on the surface or not decided the ignition, leading to the development of a luminous diffusion flame. When the Al surface was covered with an original oxide coating, it was observed that ignition occurred in the gas phase at the instant of the breaking of the coating. During combustion, the Al surface remained clean or covered with porous deposits. AlO was produced in the gas phase through the reactions of Al vapor with O 2. The AlO had a peak concentration in the gas phase away from the surface. Al 2O 3 also condensed in the gas phase. N 2 in the mixtures was found not to affect the ignition and combustion process due to much less reactivity with Al. The combustion mechanism for the Al O 2 N 2 system has been postulated, including the surface and gas-phase reactions producing Al vapor, AlO, Al 2O, AlO 2, O, and condensed Al 2O 3. The ignition mechanism is also discussed.

High Pressure Combustion – Ignition Temperatures to 1000 bar

AbstractIgnition temperatures of gaseous mixtures of methane with oxygen or air at initial pressures between 50 and 1000 bar have been measured. Two cylindrical reaction vessels of 4 and 10 cm3 and one spherical vessel with 21 cm3 volume were applied which withstand dynamic pressures up to 6000 bar at 900 K (600°C). Most experiments used the “heat‐up” method with a high pressure gas mixture heated up inside and together with the reaction vessel until spontaneous rapid reaction began. Additional experiments were made with preheated empty vessels and with forced ignition by hot wires. Spontaneous ignition temperatures for stoichiometric methane‐air mixtures are around 870 K (600°C) at atmospheric pressure and decrease to 660 K (390°C) at 1100 bar ignition pressure. Semenov plots give straight lines for various reaction conditions. Effective activation energies could be derived. With the assumption of a global reaction order of 2, the activation energy for stoichiometric methane‐air is 359±4 kJ/mole, for stoichiometric methane‐oxygen it is 253±10 kJ/mol. Considering earlier experiments with “hydrothermal” supercritical flames, ignition with added high pressure steam were made.

Spontaneous fires in insulation

AbstractCombustible liquids may self‐heat in porous insulation yielding smoldering or flaming combustion. In Part I the problem is reviewed and practical measures discussed. Using two‐inch cubes of insulation and a standardized procedure, Spontaneous Ignition Temperatures (SITs) ranging from 55‐184 C are reported for a series of combustible liquids. The application of a self‐heating parameter Z = (AIT)/(AIT‐FP), where AIT is autoignition temperature and FP is closed cup flash‐point (both in Celsius), is examined. The “Z” parameter gives some indication of materials that will self‐heat and those that will evaporate. For Z > 1.61 ignition occurred for all the liquids tested. Evaporation usually occurred for materials with Z < 1.35. It was found that some water‐reactive or peroxide‐forming materials can ignite where only evaporation would be predicted from Z value considerations. An important example of a water‐reactive material is ethylene oxide (EO); the importance of EO insulation fires is that under certain conditions explosive decomposition of EO contained in the equipment can be initiated.It was previously determined that ethylene oxide reacts in porous, refractory insulations forming low molecular weight polyethylene glycols. The formation rate depends on temperature and the type and condition (particularly water content) of the insulation. Unlike EO the glycols have low volatility and may accumulate over time to several times the mass of some insulations. Under certain conditions the glycols can ignite spontaneously. In Part II experiments carried out to examine this phenomenon are discussed.Where process temperatures are above the SIT (but below the AIT), cellular glass insulation will minimize the risk of insulation fires. One disadvantage, especially for thermally unstable materials such as EO, is that cellular glass has poor fire endurance properties. The use of a realistic fire endurance test to specify insulation thickness and additional measures such as stainless steel jackets are described.Alternatives to the use of cellular glass are discussed. When selecting an insulation system, it should be determined whether an insulation fire might occur and the loss potential from such an event should be evaluated.

Determination of spontaneous ignition temperatures of edible oils and fats by pressure differential scanning calorimetry

Samples of vegetable, edible oils and animal fats were intensively oxidized in the cell of a pressure differential scanning calorimeter (PDSC). At high oxygen pressures (800–2800 kPa) and at high heating rates (40–90°C min −1) the samples undergo spontaneous ignition. The temperatures at which ignition occurs were determined from PDSC scans. The influence of heating rate, pressures of oxygen and presence of copper on spontaneous-ignition temperatures for the studied oils and fats are discussed.

DSC‐cell ‐ A versatile tool to study thermo‐oxidation of aviation lubricants

AbstractThe versatility of a differential scanning calorimetry (DSC) cell in studying thermal and/or thermal‐oxidative degradation of lubricants is shown using ester‐based aviation turbine oils as an example.The following applications are discussed: 1. quality control of fresh and used oils by pressure differential scanning calorimetry; 2. influence of metal catalysis on oil degradation; 3. identification of volatile degradation products by PDSC gas chromatography‐mass spectrometry via a TENAX trap; 4. determination of spontaneous ignition temperatures; 5. influence of metall metal oxides, wear debris and oil degradation products on ignition behaviour; 6. inhibition of spontaneous ignition by antioxidants.

Spontaneous ignition temperatures of aviation turbine oils

The usefulness of pressure differential scanning calorimetry (PDSC) in studying spontaneous ignition of aviation turbine oils is shown. The following applications are discussed: (1) determination of spontaneous ignition temperatures (SITs) of commercial aviation turbine oils; (2) catalysis of spontaneous ignition by metal/metal oxides; (3) influence of oil degradation products, like carbonaceous deposits, volatiles and wear debris; (4) inhibition by antioxidants.

Determination of spontaneous ignition temperatures (SITs) of aviation lubricants using pressure differential scanning calorimetry (PDSC)

The usefulness of pressure differential scanning calorimetry (PDSC) in studying spontaneous ignition temperatures (SITs) of selected aero-engine oils, hydraulic fluids and greases is shown. Dependence on heating rates, oxidative medium and sample pan material was studied.

Icosahedral carboranes. XV. Monomeric carboranylenesiloxanes

Abstract : A series of carboranylenesiloxanes having molecular weights between 350 and 900 was prepared. Many of these monomeric compounds were found to be high boiling liquids which, when suitably 'end-capped', demonstrated unusual thermal stability. In general, they exhibit low ASTM viscosity slopes, low pour points, and high spontaneous ignition temperatures and flash points. (Author)

The dependence of spontaneous ignition temperature on surface to volume ratio in static systems for fuels showing a negative temperature coefficient

Certain hitherto unexplained features in the observed variation of spontaneous ignition temperatures with surface-to-volume ratio are discussed in terms of chain-thermal ignition theory. They are shown to be expected for substances that exhibit cool flames and two-stage ignitions, as is a region of “two-stage instability” at higher s/v values, not yet observed. The results are relevant to the assessment of hazards associated with spontaneous ignition in enclosed compartments such as aircraft fuel tanks.

The Ignition of Inflammable Fluids by Hot Surfaces

IN recent years, much attention has been given to spontaneous ignition problems because of the high skin temperatures of aircraft operating at high Mach numbers. The problem is not really new, however, since for many years aircraft engines have been operating with carcase temperatures above the laboratory closed vessel spontaneous ignition temperatures for fuels and lubricants, and installation engineers have collected a good deal of ad hoc data to justify the safety of particular power plants. FIG. 1 indicates the main risk areas for a typical subsonic by‐pass jet installation.

Fluoroalkylphosphonitrilates: A New Class of Potential Fire-Resistant Hydraulic Fluids and Lubricants. I.

The preparation and preliminary evaluation of a number of trimeric and tetrameric bis (α, α, ω-tri H-polyfluoroalkyl) phosphonitrilates, mixed substituted trimeric and tetrameric (phenyl-α, α, ω-tri H-polyfluoroalkyl) phosphonitrilates, and mixed substituted trimeric and tetrameric (substituted phenyl-α, α, ω-tri H-polyfluoroalkyl) phosphonitrilates is described. Many products have wide liquid ranges with pour points ranging down to —55 F. They also have high compression ignition ratios and relatively high spontaneous ignition temperatures. Good wear, and compatibility with rubber are other favorable properties. In order to obtain hydrolytically stable products, new synthesis and purification methods were developed. The compounds are promising candidates for potential use as fire-resistant hydraulic fluids and lubricants.