Ignition temperature Subject

A substance is classed as a deflagrating explosive when a small amount of it in an unconfined condition suddenly ignites when subjected to a flame, spark, shock, friction or high temperatures. Deflagrating explosives burn faster and more violently than ordinary combustible materials. They burn with a flame or sparks, or a hissing or crackling noise. 

The importance of the subject, particularly in connection with hydrocarbons, will be evident when its bearing upon explosions in coal mines is remembered.2 Of modem methods of determining ignition temperatures, the following deserve consideration ... 

Despite the high ignition temperature of methane-air mixtures of 595°C/650°C (see Table 1.3), the maximum surface temperature is subjected to a very strong limitation with respect to the unavoidable presence of coal dust with relatively low glow temperatures (see Table 1.4)... 

Firedamp-proof electrical equipment (for coal mines) is not subjected to any classification regarding ignition temperature or MESG values. 

The Gliwitsky apparatus follows a similar principle (Fig. 3.80) for measuring the self-ignition temperature. 30 cm of powder sample is subjected to a Ng stream until the initial test temperature has been reached. Switching to an air stream, linear heating is continued and the lowest test temperature at which the powder ignites is recorded as the self-ignition temperature. ... 

USA ANSl/ASTM D 1929-77 -ignition properties of plastics. Specified in some US Building Codes. This test is also known as the Setchkin test. A specimen 3 g in weight is assessed to determine the minimum temperature at which the vapour produced wilt ignite when subjected to a heated wire. 

Solvents contacting a hot surface or subjected to temperatures above the auto-ignition temperature will ignite spontaneously without an ignition source provided sufficient oxygen (air) is present. Anyone interested in the auto-ignition temperatures of a solvent should review the solvent s MSDS or contact the solvent manufacturer. 

The minimum ignition energy of Hquid acetylene under its vapor, when subjected to electrostatic sparks, has been found to depend on the temperature as indicated in Table 3 (86). Ignition appears to start in gas bubbles within the Hquid. 

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