Oxy-acetylene welding — cylinder gas consumption for neutral flame In gas welding of mild steel with a neutral oxy-acetylene flame, if acetylene consumption from the cylinder is 10 litres, the approximate oxygen consumption from the cylinder will be:

Introduction / Context:
Correct gas ratios are crucial in oxy-acetylene welding to achieve the desired flame chemistry. A neutral flame (balanced oxygen and acetylene) is typically used for mild steel to avoid oxidation or carburization. This question tests your grasp of gas consumption ratios at the torch.

Given Data / Assumptions:

• Neutral flame is used for mild steel welding.
• Acetylene consumption from the cylinder is 10 litres.
• Flow rates are measured at the torch and reflect cylinder usage.

Concept / Approach:
A neutral flame requires approximately equal volumes (by flow rate) of oxygen and acetylene at the torch. Although total oxygen involved in combustion includes atmospheric oxygen, the oxygen delivered from the cylinder to form a neutral flame at the tip is roughly equal to the acetylene flow in typical practice.

Step-by-Step Solution:
Neutral flame condition → O2 (cylinder) ≈ C2H2 (cylinder).Given C2H2 = 10 litres → O2 ≈ 10 litres.Therefore, the best choice is 10 litre.

Verification / Alternative check:
Welding guides often recommend oxygen-to-acetylene flow ratios close to 1:1 for neutral flame on mild steel, with minor adjustments for tip size and joint geometry. Significant deviations indicate oxidizing or carburizing flames, which are not desired for general mild steel welding.

Why Other Options Are Wrong:
5 litre implies carburizing conditions; 15 or 20 litre implies oxidizing flame; 8 litre under-supplies oxygen and would not be neutral under standard settings.

Common Pitfalls:
Confusing total stoichiometric oxygen needs (including air entrainment in oxy-fuel cutting) with cylinder oxygen for welding; misreading regulator scales leading to incorrect flame chemistry.

Final Answer:
10 litre