Shielding Gases & Fuel Gases

Gas isn't an accessory in welding — it's the invisible tool. Without the right gas, the weld pool would react with oxygen in the air: porosity, embrittlement, scale.

Shielding Gases

Argon, CO₂, and mixed gases (M21, M12) keep air away from the weld pool — for TIG/MAG/MIG. Helium and nitrogen for special cases.

Fuel Gases

Acetylene and propane supply the flame for oxyfuel welding, brazing, and flame straightening.

Oxygen

Supports combustion — for oxyfuel flame and cutting, never as shielding gas.

How long will your gas last?

Read the pressure on the gauge, the flow from the float/flow meter — done.

Cylinder size (water capacity)

Fill pressure

Current pressure on the gauge: 125 bar(of 200 bar)

Flow rate (l/min)

l/min — typically 5–12 (TIG), 8–15 (MAG), higher with large nozzles.

Remaining gas · 20 L cylinder at 125 bar

4 h 27 min

2,400 liters of gas left (at 9 l/min)

For comparison: full (200 bar) would be 4,000 liters.

Plan for residual pressure: Don't run the cylinder below about 5 bar — otherwise moisture gets in and the cylinder can "suck back". The calculator above already deducts these 5 bar.

Caution with two gases:CO₂ is liquid in the cylinder — the gauge reads ~57 bar almost to the end and lies about the fill level (only when it drops is it really almost done). Acetylene is dissolved in acetone, always operate the cylinder upright. This calculator doesn't apply to either.