Calculator
Gas flow & cylinder life calculator
Set the flowmeter right, then find out how many hours of arc time your cylinder holds.
Read from your cylinder label — typical free-gas volumes: D ~1,800 L, E ~4,600 L, G ~9,500 L.
Getting flow right
Too little gas and you get porous, sugared welds; too much and the laminar shield turns turbulent, pulling air in — worse, not better. For MIG with an argon–CO₂ mix (Argoshield family) in still air: 10–12 L/min for a 10–12 mm nozzle at under 200 A, 15–20 L/min for 16 mm nozzles and high-current spray. TIG on argon runs 8–12 L/min; add a gas lens for better coverage at lower flow outdoors. Any breeze over ~8 km/h and you should be sheltering the arc or switching to self-shielded flux-core — no flow rate fixes wind.
Cylinder sizes in Australia
Australian gas suppliers (BOC, Supagas, Coregas) label cylinders with free gas volume — use that number above. Typical volumes: D ≈ 1,700–2,000 L, E ≈ 4,000–4,600 L, G ≈ 8,700–10,200 L for argon mixes; check the label rather than the letter. At 14 L/min, an E-size (4,600 L) cylinder gives ~5.5 hours of arc time; a D-size (~1,800 L) ~2.1 hours.