Which gas passes through the center of a cutting torch tip?

• A. Acetylene
• B. Argon
• C. Oxygen
• D. Nitrogen

Answer: (C)

In oxy-fuel cutting, the center passage carries the oxidizer. Oxygen is directed through the center of the torch tip to the hot spot on the metal, where it reacts with the heated surface to form metal oxide that is blown away, making the cut. The surrounding outer flame, typically from the fuel gas like acetylene, provides the heat needed to bring the metal to its ignition temperature, but the actual cutting action comes from the oxygen reacting with the metal at the center. Argon and nitrogen aren’t used to perform this cutting process, as they are inert or used for shielding rather than oxidation.