Maximum spontaneous ignition temperature

The maximum spontaneous ignition temperature (SIT) or autoignition temperature (AIT) is defined as die niininiuni temperature at wliich combustion occurs in a bulk gas nii. ture wlien die temperature of a fiaiiunable gas-air mixture is raised in a uniformly heated apparatus. Tlie autoignition temperature represents... 

The autoignition temperature (AIT) or tlte maximum spontaneous ignition temperature is defined as the maximum temperature at which combustion occurs in a combustible bulk gas mixture when tlie temperature of a flammable gas-air mixture is raised in a uniformly heated apparatus. The AIT represents a tlircshold below which chemicals and combustibles can be handled s ely. (The AlTs of selected substances arc available in the literature. ) The AIT is strongly independent on tlie nature of hot surfaces. The AIT may be reduced by as mudi as 100-200°C when the surfaces arc contaminated by dust. When tlie temperature of a flanuiiable mi.xturc is raised to or above the autoignition temperature, ignition is not spontaneous. Most notably in liquids, there is a finite delay before ignition lakes place, i.e., a lapse between the time tlicrc is a flammable mixture reaches its flame temperature and tlie first appearance of a flame. An equation tliat correlates with the ignition temperature is also available in the literature. ... 

Fuel Quantity of fuel per Gf" Flammability limit ia air, vol % gas Lower Higher Maximum flame speed, cm/s Spontaneous ignition temperature, °C Ignition d -jC energy, m ... 

Substance Quantities Maximum Temperature Rise Recorded, AT °F Time to Maximum Temperature, tm min Spontaneous Ignition Toxic Gas... 

The autoignition temperature of a substance is the temperature at which it will ignite spontaneously in air, without any external source of ignition. It is an indication of the maximum temperature to which a material can be heated in air for example, in drying operations. 

In order to classify a gas or vapour by its ability to be ignited by a hot surface, the definition Temperature Class is used. Ignition by this classification is spontaneous or automatic. The classification is simple to apply and consists of a two-digit code, the first digit is the letter T and second a number between 1 and 6. The lower the number the higher the maximum allowable surface temperatme. Hence a T6 gas or vapour is relatively more hazardous than one with a T1 code, see Table 10.3. 

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