Regarding the auto-ignition temperature of oils
Thread Content
Why does the heavier the oil, that is, the greater its molecular weight, the lower its auto-ignition temperature? Which expert can explain this from a microscopic perspective?
Take a look at this: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=647691
Spontaneous combustion requires the accumulation of heat. Light oil vaporizes rapidly when heated; this vaporization absorbs heat, thereby lowering the temperature of the liquid phase. As a result, it is difficult for such oil to reach the temperature necessary for spontaneous combustion, so its ignition point is high. Heavy oil, on the other hand, does not vaporize easily, allowing heat to accumulate more readily; hence its ignition point is low. The flash point occurs when the vapor phase of a flammable substance mixes with air to form an explosive mixture that can explode upon contact with a flame. Light oil vaporizes in large quantities when heated, which facilitates the formation of an explosive gas; therefore its flash point is low. Heavy oil, however, does not vaporize easily, so a higher temperature is required for it to vaporize and reach the explosive limit, which results in a higher flash point.