Flash point

The flash point is the set of ambient conditions in which a flammable substance is able to initiate combustion if a heat source is applied at a sufficient temperature, reaching the point of ignition . Once the external heat source is removed, two things can happen: keep the combustion started, or turn the fire on by itself.

The difference between the flash point and the ignition point is that in the first case the fuel is able to ignite, but it lacks the heat of ignition; the point of ignition is in case the ignition has already occurred, ie the ignition heat has been applied.

Considering normal pressure conditions (normal atmospheric pressure of 101,3 kPa), these conditions are reduced to a minimum temperature and a specified proportion of fuel vapor in the ambient air, which can occur in a small part of the same. Both the temperature and the proportion of the mixture are important. In fact, the temperature can be relatively low, most of the time less than normal in the environment, but at that temperature the liquid fuels begin to release vapors which, when mixed with the oxygen of the air or other oxidizer, can give the conditions , so that any spark that reaches the required ignition temperature, initiates the fire. Among these conditions, the ratio of gases to air is fundamental and, if the gas ratio is low or excessive, ignition will not occur.

The Pensky-Martens apparatus is used to measure the flash point. Flammability of certain substances

Felix Esparza, Fire or Combustion, p. 15

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