Oxy–acetylene flame chemistry: An oxidising flame is produced when the volumes of oxygen and acetylene are exactly equal. Assess the correctness of this statement.

Introduction / Context:
In oxy–acetylene welding and cutting, flame type is controlled by the oxygen-to-acetylene ratio. Correct flame selection affects temperature, oxidation potential, and weld quality (porosity, brittleness, and surface finish).

Given Data / Assumptions:

• Fuel gas: acetylene; oxidiser: oxygen.
• Flame categories: carburising (reducing), neutral, and oxidising.
• Equal “volumes” refers to equal flow rates.

Concept / Approach:
A neutral flame occurs when oxygen and acetylene are supplied in approximately equal amounts, producing a well-defined inner cone and a colourless outer envelope with minimal excess oxygen or fuel. An oxidising flame requires excess oxygen beyond the neutral ratio and is characterised by a shorter, sharper inner cone and a more intense hissing sound. A carburising (reducing) flame occurs with excess acetylene and shows a visible acetylene feather. Therefore, equal volumes do not produce an oxidising flame; they produce a neutral flame.

Step-by-Step Solution:
Set oxygen-to-acetylene ratio to ~1:1 → neutral flame.Increase oxygen above 1:1 → oxidising flame.Decrease oxygen below 1:1 (excess fuel) → carburising flame.Hence, the statement is false.

Verification / Alternative check:
Welding handbooks depict neutral flame at equal flow and oxidising flame at oxygen-rich settings, confirming the distinction.

Why Other Options Are Wrong:
“True” contradicts standard flame definitions.

Carburising at equal volumes is incorrect; carburising requires excess acetylene.

Preheating or cutting operations do not change the fundamental chemistry of the gas ratio that defines flame type.

Common Pitfalls:
Confusing visual cues of flames; relying solely on sound rather than cone shape and feather observation; using oxidising flames on steels, which can cause oxidation and brittleness.

Final Answer:
False