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    Thursday, January 23, 2020

    Importance of 'flash-point' and 'fire-point'

    In many engineering applications, fuels are used for getting thermal energy by combustion of fuel. For example, an oil-fired furnace, oil is ignited and heat is used for heating the metals to alter their properties.

    Fuel selection is also one of the most important parts. One needs to use and select fuel based on its properties like calorific value, density, viscosity, specific heat, and flash/fire point. Now, what is the meaning of a flashpoint and fire point?

     'Flash Point is temperature and the property of a volatile lubricant/fuel which suggests when volatile lubricant/fuel gives off sufficient vapor when heated, it will start to ignite for a moment but not lasts more than few seconds.

     'Flash Point' requires ignition source whereas 'auto-ignition temperature' does not require a source of heat. While 'Flash Point' depends on the vapor pressure of that lubricant/fuel and it increases as the temperature of fuel/lubricant increases. Flashpoint and fire point can be determined experimentally by use of Cleveland's open apparatus and Abel's closed cup apparatus. 

    E.g. Petrol's 'Flashpoint' is around -43 degree C and its auto-ignition temperature is about 280 °C. ; 

    Diesel's 'Flash Point' is normally greater than 52 °C and its auto-ignition temperature is about 256 °C. 

    And Fire Point is the temperature at which if fuel is heated to give off sufficient vapors so it can continue to burn for more than 5 seconds is called 'Fire Point'. Normally 'Fire Point' is more than 'Flash Point' by 10-20 °C. 'Flash Point' and 'Fire point' are determined to measure fire resistance and its volatility.

    Importance of flash point and fire point:

    By knowing the value temperature at which fuel catches fire, one can store the fuel and transport it accordingly. This is why knowing petrol and diesel's flash point and fire point, every petrol pump wants petrol and diesel to be stored underground. Thus, flash point and fire point help in determining the nature of fuel's Flammability. A lower value of flash point means fuel is highly flammable.


    1. Hello, my name is Rushikesh.from SE mech.

      If we got flash point of a fuel,then why should we go for fire point ? What is the advantage of fire point over flash point ?

    2. why diesel has higher flash point than petrol

    3. why diesel has higher flash point than petrol and also calorific value


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