Gas flames in welding — the temperature of an oxy-hydrogen flame compared with an oxy-acetylene flame is:

Introduction / Context:
Oxy-fuel gas flames are widely used for welding, cutting, and brazing. This question checks familiarity with typical peak flame temperatures for common gas combinations and their relative capabilities in welding operations.

Given Data / Assumptions:

• Oxy-acetylene flames reach approximately 3200–3500 °C at the inner cone under neutral settings.
• Oxy-hydrogen flames reach approximately 2600–2800 °C under comparable conditions.
• Comparisons are qualitative: less than, same as, or more than.

Concept / Approach:

Flame temperature depends on the heat of combustion and the specific heat of reaction products. Acetylene has a higher heat of combustion per unit oxygen and produces a hotter inner cone than hydrogen under typical oxy-fuel ratios, which is why oxy-acetylene is preferred for gas welding steel, while oxy-hydrogen is often used for brazing, glass working, and applications requiring a cleaner but cooler flame.

Step-by-Step Solution:

Verification / Alternative check:

Handbooks and welding data sheets consistently list higher peak temperatures for oxy-acetylene than for oxy-hydrogen under neutral flames.

Why Other Options Are Wrong:

“Same as” contradicts widely published temperature data; “more than” is incorrect because oxy-acetylene is hotter.

Common Pitfalls:

Confusing cleanliness of flame with temperature; oxy-hydrogen is cleaner but not hotter than oxy-acetylene.

Final Answer:

less than