Ignition temperature, definition

As a result of these new testing methods the following terminology for ignition temperature definitions has been proposed ... 

NFPA now normally refers to autoignition as the Hot Flame Ignition Temperature, as a more precise definition. Subsequently the following two additional terms are being adopted by NFPA to further refine the ignition properties of materials. The lowest temperatures at which cool flame ignitions are observed are named the Cool Flame Reaction Threshold (CFT). The lowest flame temperatures at which an exothermic gas phase reaction is noticed are named the Preflame Reaction Threshold (RTT). 

Explosion (Detonation, Deflagration or Ignition) Temperature, It is the temperature at which an explosive, propellant or pyrotechnic composition explodes, detonates, deflagrates or ignites within a definite time, say 0.1t 1-0 or 5.0 seconds. Various methods for its determination arebriefly described in Vol 1, p XVI under Ignition (or Explosion) Temperature Tests... 

Cartridges containing only potassium chlorate were transported in safety to the site, where they were dipped for a definite time into kerosene just before use. Miedziankit was also manufactured by soaking potassium chlorate cartridges with kerosene in the explosive factory. Kerosene with an ignition temperature above 30°C was employed, to render the product safe for rail transport. According to T. Urbanski [76] the rate of detonation of Miedziankit is 3000m/sec in an iron pipe at a density of 1.7. 

The ignition temperature rises with the pressure (vide infra). The diameter of the tube is without influence between the range 3-6 to 11 mm. With tubes of diameter less than 0-5 mm. no definite ignition temperature has been observed.4... 

When white phosphorus is heated at 200° under a pressure of 12,000 kgm. per sq. cm., transformation takes place into another allotropic modification known as black phosphorus. This forms a black crystalline solid, insoluble in carbon disulphide. It can be ignited with difficulty with a match, its ignition temperature in air being about 400°. When heated in a closed tube it vaporises and condenses to violet and white phosphorus. It differs from the other forms of phosphorus in being a conductor of electricity. Its density is 2 691, The question of the relative stability of violet and black phosphorus has perhaps not yet been definitely settled but the results obtained point to violet phosphorus being the more stable form, ... 

The ignition temperature is used to characterize the susceptibility of a liquid to self-ignite at a hot surface. This conforms to its definition as the lowest temperature under standardized conditions at which ignition is observed if a liquid gets into contact with a hot surface in the presence of air. Standards which describe the test method in detail are the German DIN 51794 and the European Directive L383-A98, aimex 9... 

Sprinkle a little water on the external surface of the process unit or the gas duct. If it boils off immediately, the temperamre is more than 100 °C. Now draw a line on the surface with a piece of solid sulphur—if it melts immediately, the temperature is more than 120° if it ignites, it is 250 °C. If a line is drawn with a piece of lead melts, then it is 330 °C. Such surface temperatures definitely indicate damage of internal refractory lining (melting point of tin is 232 °C and zinc is 419.4 °C. These can also be used). 

Cone calorimetric evaluations of polymer-clay nanocomposites indicate that PHRR and mass loss rate (MLR) can be significantly reduced when compared to the pure polymer. However, in many cases, the ignition temperature is lower, the total heat released (THR) has not changed, and the total mass loss (TML) has not changed for the polymer-clay nanocomposites when compared to the pure polymer. An examination of the flame-retardant behavior of polymer-clay nanocomposites indicates that the presence of the clay delays the decomposition of polymer in the cone calorimeter test and does not prevent the decomposition. These observations in relation to the definitions listed above for flame retardants excludes clay from being considered to be a flame retardant in the same category as commercially available flame retardants. Because of these inadequacies, considerable effort has been made to identify synergies that may exist between commercial flame retardants and clay in polymer. 

These variables that relate to increased thermal stability of the polymer in polymer-clay nanocomposites extrapolate directly to improved flame retardancy of polymer-clay nanocomposites. The improvement in flame retardancy provided by polymer-clay nanocomposites does not completely satisfy the criteria found in the definitions for traditional commercial flame retardants. Lower ignition temperatures, no change in the total heat release, and no change in total mass loss as measured by cone calorimetry of the polymer-clay nanocomposites when compared to the pure polymer prevent the classification of clay in polymer-clay nanocomposites as a flame retardant. Flame-retardant synergies between commercial flame retardants and polymer-clay nanocomposites have mitigated some of the flame-retardant deficiencies of the polymer-clay nanocomposites and allow for their commercial introduction into products. 

Bismuth trioxide may be prepared by the following methods (/) the oxidation of bismuth metal by oxygen at temperatures between 750 and 800°C (2) the thermal decomposition of compounds such as the basic carbonate, the carbonate, or the nitrate (700—800°C) (J) precipitation of hydrated bismuth trioxide upon addition of an alkah metal hydroxide to a solution of a bismuth salt and removal of the water by ignition. The gelatinous precipitate initially formed becomes crystalline on standing it has been represented by the formula Bi(OH)2 and called bismuth hydroxide [10361 -43-0]. However, no definite compound has been isolated. 

Good heat transfer on the outside of the reactor tube is essential but not sufficient because the heat transfer is limited at low flow rates at the inside film coefficient in the reacting stream. The same holds between catalyst particles and the streaming fluid, as in the case between the fluid and inside tube wall. This is why these reactors frequently exhibit ignition-extinction phenomena and non-reproducibility of results. Laboratory research workers untrained in the field of reactor thermal stability usually observe that the rate is not a continuous function of the temperature, as the Arrhenius relationship predicts, but that a definite minimum temperature is required to start the reaction. This is not a property of the reaction but a characteristic of the given system consisting of a reaction and a particular reactor. 

The flash point represents the minimum temperature at whieh an ignitable mixture exists above a liquid surfaee. By definition, flash points are inapplieable to gases. Some solids, e.g. naphtlialene and eamphor, are easily volatilized on heating so that flammable mixtures develop above the solid surfaee and henee flash points ean be determined. (However, although these substanees ean be ignited, they generally need to be heated above their flash points in order for eombustion to be sustained this is the fire point .)... 

After a precipitate has been filtered and washed, it must be brought to a constant composition before it can be weighed. The further treatment will depend both upon the nature of the precipitate and upon that of the filtering medium this treatment consists in drying or igniting the precipitate. Which of the latter two terms is employed depends upon the temperature at which the precipitate is heated. There is, however, no definite temperature below or above which the... 

---