Which flame type would you observe when acetylene content is higher than needed in an oxy-acetylene flame?

Which flame type would you observe when acetylene content is higher than needed in an oxy-acetylene flame?

• A. Oxidizing flame
• B. Neutral flame
• C. Carburizing flame
• D. Invisible flame

Answer: (C)

When the acetylene amount is in excess, you get a fuel-rich flame. In oxy-acetylene welding, the flame’s appearance changes with the fuel-to-oxygen ratio. Too much acetylene means not all of it can burn, so soot forms and the flame becomes smoky and luminous, characteristic of a carburizing (fuel-rich) flame. This creates a reducing environment that can deposit carbon on the workpiece. The neutral and oxidizing flames, by contrast, are cleaner and blue with less soot, and an invisible flame isn’t the typical outcome here.

When the acetylene amount is in excess, you get a fuel-rich flame. In oxy-acetylene welding, the flame’s appearance changes with the fuel-to-oxygen ratio. Too much acetylene means not all of it can burn, so soot forms and the flame becomes smoky and luminous, characteristic of a carburizing (fuel-rich) flame. This creates a reducing environment that can deposit carbon on the workpiece. The neutral and oxidizing flames, by contrast, are cleaner and blue with less soot, and an invisible flame isn’t the typical outcome here.