Page 3 - LN

Structure of a flame

A flame consists of three zones. These
are the innermost zone, middle zone, and
the outermost zone.

I. The innermost zone of a flame is
dark. It consists of hot, unburnt
vapours of the combustible
material. It is the least hot zone of
the flame.
II. The middle zone of a flame is
yellow. It is bright and luminous.
The fuel burns partially in the
middle zone because there is not
enough air for burning in this zone.
The partial burning of fuel in this
zone produces carbon particles. These particles become hot and emit light.
III. The outermost zone of a flame is blue. It is a non-luminous zone. In this zone,
complete combustion of the fuel takes place because there is plenty of air around it.
This zone has the highest temperature in the flame. The goldsmith uses a blower to
blow the outermost zone to melt gold and silver