Using Table 15, determine the minimum gas flow rate for a 1/2" nozzle.

• A. 17-20 cfh, or 8-9.4 L/min
• B. 5-10 cfh
• C. 25-30 cfh
• D. 12-15 cfh

Answer: (A)

The main idea is that shielding gas flow must be high enough to create a continuous protective envelope around the weld pool, and nozzle size dictates how much gas is needed. A 1/2" nozzle is larger, so it requires more gas to cover the weld area effectively and prevent air from entering the shield.

For a 1/2" nozzle, the minimum shielding gas flow shown in Table 15 is 17-20 cfh, which is about 8-9.4 L/min. This range represents the flow rate that reliably maintains shielding under typical torch standoff and conditions. Going below this minimum can allow the shield to break down, leading to porosity or contamination of the weld.

If you ever work in a windy environment or at different torch distances, you might adjust upward from this minimum to maintain adequate shielding, but the stated range is the expected minimum for a 1/2" nozzle.