-The maximum temperature of oxy-acetylene flame is 3100 - 3500 degree Celsius and the center of the heat concentration is just at the extreme tip of the white cone. Combustion of gas mixture is recognized as taking place in two main stages.
Stage 1 : Oxygen and acetylene in equal proportion by volume burn in the inner white cone.The oxygen combines with carbon of the acetylene and form carbon monoxide ,while the hydrogen is liberated.
Stage 1 : Oxygen and acetylene in equal proportion by volume burn in the inner white cone.The oxygen combines with carbon of the acetylene and form carbon monoxide ,while the hydrogen is liberated.
2 C2H2 + 2O2 ----> 4CO + 2H2
Stage 2: Upon passing into the outer envelope of the flame two more reactions takes place as combustion is completed. The carbon monoxide use the oxygen supplied from the air surrounding the flame and as a result of burning forms carbon-dioxide. The hydrogen also burns with the oxygen (from the atmosphere) and forms water-vapor (H2O).
4CO + 2H2 + 3O2 --> 4CO2 + 2H2O
Combining the above two equations
2C2H2 + 5O2 --->
4CO2 +2H2O
It can be seen that the above two-fifth of the oxygen necessary for the complete combustion of acetylene is got from the cylinder whereas the rest comes from the surrounding atmosphere.
