Flame

key notes :

Definition of a Flame

  • A flame is a visible, gaseous part of a fire. It results from the combustion of a material in the presence of oxygen.

Structure of a Flame

A flame typically has three zones:

  • Innermost Zone: Dark and unburnt. It contains unburnt fuel and is the coolest part.
  • Middle Zone: Luminous and yellow. It is moderately hot and contains partially burnt carbon particles.
  • Outermost Zone: Non-luminous and blue. It is the hottest part where complete combustion occurs.

Types of Flames

  • Luminous Flame: Yellow in color, occurs due to incomplete combustion. It produces more light and soot.
  • Non-Luminous Flame: Blue in color, occurs due to complete combustion. It is hotter and cleaner.

Conditions for Combustion

  • Presence of a combustible substance.
  • Availability of oxygen.
  • Ignition temperature (minimum temperature required to ignite the substance).

Examples of Flames

  • Candle flame (luminous flame).
  • Gas stove flame (non-luminous flame).

Applications of Flames

  • In domestic cooking (blue flame for higher efficiency).
  • In industries (welding torches use oxyacetylene flames).

Safety Measures

  • Avoid flammable materials near open flames.
  • Use fire extinguishers to control accidental fires.

Flame and Pollution

  • Incomplete combustion in flames releases pollutants like soot and carbon monoxide.

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