The neutral flame is the flame in which the amount of oxygen is precisely enough for burning, and neither oxidation nor reduction occurs. A flame with a good balance of oxygen is clear blue. The reducing and neutral flames are useful in soldering and annealing.
Neutral Welding Flame. The neutral flame has a one-to-one ratio of acetylene and oxygen. It obtains additional oxygen from the air and provides complete combustion. It is generally preferred for welding.
The maximum flame temperature occurs At the inner cone.
The maximum temperature of Oxy-hydrogen flame is about 2,800 °C.
The temperature of the oxyacetylene flame 3480 °C.
A neutral flame is obtained by supplying an Equal volumes of oxygen and acetylene.
When more volume of acetylene and less volume of oxygen is supplied, then a Carburising flame is obtained.
carburizing flame is one with little oxygen, which produces a sooty, lower-temperature flame. It is often used to anneal metal, making it more malleable and flexible during the welding process.