In another words:
- Flash point is the lowest temperature at which there will be enough flammable vapor to induce ignition when an ignition source is applied.
- The lower the flash point, the easier it is to ignite the material.
Flash point example
Gasoline has a flash point of approximately -40º C and diesels flash point is around +60° C.
It is therefore easier to ignite gasoline than diesel.
How to Determine Flash Point
Flash points are determined experimentally by heating the liquid in a container (cup) and then introducing a small flame just above the liquid surface.
The temperature at which there is a ignition is recorded as the flash point.
What affects flash point
Density
Higher density means higher flash point.
Boiling point
Higher boiling point, means higher flash point.
Contaminants
Any contaminants like water, iron and others will impact the flash point.
Does flash point change with pressure
The flash point decreases if the ambient pressure decreases
Flash point vs fire point
Flash point explains the lowest temperature for ignition, but the ignition may not be sustained.
Fire point explains the lowest temperature where ignition is achieved and the ignition sustained for some time.
Note: The fire point is always slightly higher than the flash point.
Flash point vs boiling point
Flash point and boiling point are two terms we use for the liquid state of substances.
The key difference between flash point and boiling point is that the term flash point is applied for a volatile liquid, whereas the term boiling point can be applied for any liquid.
Flash point vs auto ignition
The flash point is sometimes confused with the auto ignition temperature, the temperature that causes spontaneous ignition. But they are not the same thing.
The flash point temperature is lower than the ignition temperature.
The key difference between flash point and auto ignition temperature is:
- Flash point determines the lowest temperature at which vapor of a material starts ignition in the presence of an ignition source.
- The auto ignition temperature is the lowest temperature at which a material can start ignition spontaneously.
Flash point vs melting point
Flash point and melting point are not related. Flash point refers to liquid substances.
The melting point of a substance is the temperature at which it changes state from solid to liquid.
Flash point is the lowest temperature at which vapors from a liquid substance ignite in air, when exposed to flame.
Can Flash Point Be Negative
Yes. In the example I gave above gasolines flash point is -40°C.
Can Flash Point Be Lower Than Boiling Point
The flash point is always lower than the corresponding boiling point.
At the normal boiling point of the liquid, the partial pressure of the flammable vapor will be 1 atm, essentially displacing all the oxygen and nitrogen.
With some exceptions, vapor that does not contain oxygen will not ignite.
In other words, a flash point equal to the normal boiling point is impossible.
How to Increase Flash Point Of Diesel
Iron powder is used for the high flash point diesel (around 52 and 96 °C). That makes it a much safer fuel.
COMMENTS