Mechanical Engineering - Workshop Technology - Discussion

The correct answer is: 70 to 280 kN/m2 (7 to 28 bar).

For gas welding, the recommended pressure for acetylene at the welding torch is between 70 to 280 kN/m2 (7 to 28 bar). This pressure range allows for a stable and controlled flame, which is essential for achieving high-quality welds.

Here's a breakdown of the typical pressure ranges for acetylene:

- Low-pressure welding: 7-14 bar (70-140 kN/m2).
- Medium-pressure welding: 14-21 bar (140-210 kN/m2).
- High-pressure welding: 21-28 bar (210-280 kN/m2).

The other options are incorrect because:

- 7 to 103 kN/m2 (0.7 to 10.3 bar) is too low for most welding applications.
- 280 to 560 kN/m2 (28 to 56 bar) is too high and may cause instability in the flame.
- 560 to 840 kN/m2 (56 to 84 bar) is excessively high and not typically used for welding.

The exact pressure required may vary depending on the specific welding application, torch design, and personal preference.

For acetylene - 7 to 103.
For oxygen - 70 to 280.